IST WINNER II D v1.0 The WINNER Role in the ITU Process Towards IMT-Advanced and Newly Identified Spectrum

Transcription

1 IST WINNER II D v1.0 The WINNER Role in the ITU Process Towards IMT-Advanced and Newly Identified Spectrum Contractual Date of Delivery to the CEC: End of November 2007 Actual Date of Delivery to the CEC: 26 th November 2007 Author(s): Participant(s): Workpackage: Estimated person months: 17 Security: Nature: Claes Eriksson, Tim Irnich, Miia Mustonen (editor), Pekka Ojanen, Carl Wijting, Roufia Yahi EAB, AU, VTT, NOK, FT WP 5 - Spectrum PU R Version: 1.0 Total number of pages: 44 Abstract: The content of this deliverable is twofold. Firstly, the work done within WINNER II project towards the World Radiocommunication Conference 2007 is described and a summary of the conference outcome is given. From the ITU-R WP 8F point of view spectrum estimate results and candidate bands are shortly summarised and the results of the sharing study are introduced. Also the role of the Conference Preparatory Meeting and European Common Proposals to the preparation towards WRC-07 are explained. Secondly, the ongoing process towards standardization of IMT-Advanced is described, both in general and in terms of contributions developed within WINNER II project to the process. Keyword list: ITU-R, IMT-Advanced, spectrum, sharing, fixed satellite service, FSS, candidate bands, World Radiocommunication Conference, WRC 2007, circular letter, minimum requirements, evaluation, RIT, Radio Interface Technology Disclaimer: Page 1 (44)

2 Executive Summary This Deliverable is a summary of the work done within WINNER II towards two important goals of ITU- R WP 8F: World Radiocommunication Conference 2007 and standardization of IMT-Advanced. By participating to the preparations towards WRC-07 it has been possible to make every effort to ensure that the delivery of all foreseen services becomes possible and deployment of the planned networks is not hampered by unavailability of sufficient spectrum or by other regulatory issues. WINNER II focus on the process towards WRC-07 has been on the agenda item 1.4. This has resulted in a considerable amount of technical input documents addressing in particular spectrum requirements for IMT-Advanced taking into account the methodology and input parameters, relevant sharing studies and relevant information about new radio systems based on WINNER II, their performance and spectrum requirements. The contributions have been made on three different levels; on the national level through the individual European administrations that have been approached bilaterally. On European level to CEPT, especially to ECC PT1, aiming to get the WINNER II contributions agreed European contributions to the ITU-R. On international level contributions were sent to ITU-R WP 8F and to the Conference Preparatory Meeting. For the sharing studies between systems like WINNER in the Mobile Service and systems in the Fixed Satellite Service different ways of sharing and possible ways to improve the sharing situation are described. It has been essential for WINNER II as a research project to be involved in the process towards IMT- Advanced in order to ensure that the IMT-Advanced requirements give room for the WINNER technologies and make use of existing advanced WINNER features. Circular letter invites Member States, Sector Members and Associates of Study Group 8, and additionally to the external organizations to propose Candidate Radio Interface Technologies for IMT-Advanced introducing new capabilities of IMT that go beyond those of IMT The work in ITU-R WP 8F has been done in parallel in several working groups addressing the technical minimum requirements for spectrum, services, and technology and the test environments and evaluation. WINNER II partners have been taking part in creating all the minimum requirements and the evaluation process via contributions and by actively taking part in the meeting discussions. The work on the circular letter is ongoing and therefore the final decisions about the content and the minimum requirements have not yet been made. Additional contributions are being planned in the framework of WINNER II project for the minimum requirements towards the WP 8F meeting in January With the outcome of WRC-07 the utilisation of the new bands, both the global ones and regional ones, needs to be considered and defined by means of ITU-R Recommendations. This work would then be ongoing for some years. The additional amount of spectrum for Mobile Service and identified for IMT at WRC-07 could be generalised to 120 MHz globally and 392 MHz in many areas. This is less than the WINNER and ITU calculated required amounts and would then lead to the conclusion that additional spectrum would be needed in the future to provide the estimated services. After the circular letter has been sent out and the candidate radio interface technologies have replied by sending their proposals to the ITU-R WP 8F, the proposals will be evaluated with regard to the requirements set by ITU. Eventually one or several radio interface technologies that comply with the specification will be selected to become IMT-Advanced and gain access to radio spectrum identified for IMT. Page 2 (44)

3 Authors Partner Name Phone / Fax / AU Tim Irnich Phone: Fax: tim@comnets.rwth-aachen.de EAB Claes Eriksson Phone: Fax: claes.a.eriksson@ericsson.com FT Roufia Yahi Phone: Fax: roufia.yahi@orange-ftgroup.com NOK Pekka Ojanen Phone: Fax: pekka.ojanen@nokia.com NOK Carl Wijting Phone: Fax: Carl.Wijting@nokia.com VTT Miia Mustonen Phone: (editor) Fax: Miia.Mustonen@vtt.fi Page 3 (44)

4 List of abbreviations and symbols 3GPP 3 rd Generation Partnership Project AH-CL Ad-hoc Circular Letter APT Asia-Pacific Telecommunity BWA Broadband Wireless Access CCH Common Channel CDMA Code Division Multiple Access CEPT European Conference of Postal and Telecommunications Administrations CL Circular Letter CPG Conference Preparatory Group C-plane Control plane CPM Conference Preparatory Meeting of the ITU-R DL Downlink DNR Draft New Report/Recommendation of the ITU-R DVB Digital Video Broadcasting ECC PT1 Electronic Communication Committee Project Team 1 of CEPT ECP European Common Proposal ES Earth Station FBWA Fixed Broadband Wireless Access FDD Frequency Division Duplexing FPLMTS Future Public Land Mobile Telecommunication Systems FSS Fixed Satellite Service FTP File Transfer Protocol FWA Fixed Wireless Access GSM Global System for Mobile communications IBS Interference level of the Base Station IEEE Institute of Electrical and Electronics Engineers IMAP Internet Message Access Protocol IMS Interference level of the Mobile Station IMT International Mobile Telecommunications I/N Interference to Noise Ratio IPR Intellectual Property Rights ITU International Telecommunication Union ITU-R International Telecommunication Union Radiocommunication Sector ITS Intelligent Transportation Systems LTE Long Term Evolution MBWA Mobile Broadband Wireless Access MS Mobile Service OFDMA Orthogonal Frequency Division Multiple Access pfd power flux-density PDNR Preliminary Draft New Recommendation/Report QoS Quality of Service RAP Radio Access Point RAT Radio Access Technique RIT Radio Interface Technology RR Radio Regulations SWG Sub Working Group within Working Party 8F of ITU-R TDD Time Division Duplexing U-plane User plane VoIP Voice over Internet Protocol WARC World Administrative Radio Conferences of the ITU-R WG Working Group within Working Party 8F of ITU-R WLAN Wireless Local Area Network WP 8F Working Party 8F of ITU-R IMT-2000 and systems beyond IMT-2000 WRC World Radiocommunication Conference of the ITU-R Page 4 (44)

5 Table of Contents 1. Introduction Background Preparations for the WRC-07 agenda item 1.4 from WINNER perspective Overall process WP 8F work Estimate conclusions Time-shift approach Spectrum requirements Candidate bands Sharing Improved methodology Mitigation technique: sector disabling Results Influence of the IMT base station e.i.r.p Further mitigation techniques Band segmentation Conference preparatory meeting (CPM) ECPs and possible impact on WINNER ITU process towards IMT-Advanced Development of the circular letter Overall time schedule Related WP 8F deliverables Circular letter structure Process after circular letter WINNER contributions to technical requirements of IMT-Advanced Service classification Background for service classification Service classification as contributed to IMT.SERV Service-related requirements Spectrum-related requirements Requirements related to technical system performance for IMT-Advanced radio interface Peak data rates Transport delay Control plane latency Mobility Handover Security Test environments and evaluation methodology Layered approach Proposed test environments Channel models Traffic models Deployment models Outcome of WRC-07 and impact on WINNER Conclusions and Outlook References Page 5 (44)

6 1. Introduction This Deliverable summarises the WINNER II role in the ITU process towards IMT-Advanced and newly identified spectrum, addressing e.g. requirements for IMT-Advanced and sharing between services in candidate bands. The work described in this deliverable has been conducted through contributions to CEPT ECC PT1 and ITU-R provided by WINNER II partners during the years 2006 and There are two closely related WINNER II Deliverables that describe the work done previously. In WINNER II Deliverable D Spectrum Requirements for System beyond IMT-2000 the spectrum requirements estimation related work in WINNER II is described. In WINNER II Deliverable D WINNER II Spectrum Sharing Studies the first results of spectrum sharing studies performed between IMT-Advanced systems in the Mobile Service and systems in the Fixed Satellite Service in the candidate bands and MHz are introduced. This Deliverable is organized as follows. In Chapter 2, technology trends and ITU-R vision on IMT- Advanced are explained. Chapter 3 introduces the recent development in the preparation for World Radiocommunication Conference 2007 (WRC-07). The emphasis is given to agenda item 1.4 with the target to consider frequency-related matters for the future development of IMT-2000 and systems beyond IMT-2000 taking into account the results of ITU-R studies in accordance with Resolution 228 (Rev.WRC-03) which has been the main focus of WINNER II contributions. Agenda item 1.4 includes studies on the estimate of the required spectrum for IMT-Advanced, the possible bands where IMT- Advanced could be deployed and the sharing studies for these candidate bands. In Chapter 4, the ITU process towards IMT-Advanced is described. The development of the Circular letter (CL) inviting candidate radio interface technology (RIT) proposals and the following process are described. Chapter 5 describes the WINNER II effort in the development of the Circular letter. WINNER II partners have contributed in several aspects of the CL development and been involved in developing the minimum requirements to be set for the IMT-Advanced systems in all three different categories: service, technology, and spectrum related requirements. In addition to the minimum requirements, WINNER II partners have also been involved in developing the test environments and the evaluation aspects. The development of the CL is ongoing and the final CL is scheduled to be sent forward in February In Chapter 6, the outcome of World Radiocommunication Conference 2007 is explained. The outcome is assessed in terms of the impact that it has to WINNER, 4G systems and the future research in general. Chapter 7 concludes the deliverable by giving an outlook. Page 6 (44)

7 2. Background Spectrum is an essential but limited resource in wireless communications. The continuous increase in number and popularity of wireless communication systems has led together with the emergence of new services to an increased demand for more spectrum. Initially the WARC-92 identified some bands for Future Public Land Mobile Telecommunication Systems (FPLMTS). This name was later changed to IMT As a consequence of the global success of GSM already by the year 2000 a need for more spectrum was recognized. This ended up in that the WRC-2000 identified additional spectrum for IMT and the amount was estimated to be sufficient by year The identified spectrum was meant to facilitate the predicted capacity growth of IMT-2000 with high data rate, delay sensitive and high envisioned services. However, it was foreseen that the evolution does not stop by year Accordingly ITU-R prepared soon after the WRC-2000 a Framework Recommendation M.1645 to address the vision of the future mobile communication. The vision of the ITU-R and international research community of IMT-Advanced is a ubiquitous radio system concept offering further enhanced performance and providing wireless access for a wide range of services and applications across all environments. The widened scope of IMT-Advanced is shown in Figure 2-1. Mobility FIGURE 2-1 ITU-R Framework High IMT-2000 Enhanced IMT-2000 New Mobile Access New Radio Interface Medium Enhancement Low New Nomadic / Local Area Wireless Access Low Medium High Communication speed / Carrier bitrate (Mbit/s) In [M.1645], the framework and overall objectives of the future development of IMT-2000 and systems beyond IMT-2000 for the radio access network is defined. Concerning the timing it states: Systems beyond IMT-2000, for which there may be a need for a new wireless access technology to be developed around the year 2010, capable of supporting high data rates with high mobility, which could be widely deployed around the year 2015 in some countries. WINNER II project has developed a system concept for a future mobile and wireless communication system by taking into account ITU-R vision for IMT-Advanced. WINNER system concept will support higher data rates foreseen for IMT-Advanced and the predicted new services. It will also make efficient use of the radio spectrum to minimise the cost-per-bit. WINNER will provide a wide range of services and application across all environments from local area to wide-area, with one single adaptive system concept for all envisaged radio environments. It will efficiently adapt to multiple deployment scenarios by utilising different characteristics of the building blocks of a common technology basis. This is built on the recognition that developing separate systems for different purposes (cellular, WLAN, short-range access etc.) would not be optimal. Compared to current and evolving mobile and wireless systems like the 3GPP LTE, the WINNER system concept aims to provide significant improvements in peak data rate, latency, mobile speed, spectrum efficiency, coverage, cost-per-bit and supported environments taking into account specified Quality-of- Service requirements. Compared to the emerging wireless technologies e.g. those defined by the IEEE, in many cases the new technologies represent a performance improvement, but a set of technologies would Page 7 (44)

8 be needed to cover the full range of performance requirements that are foreseen for IMT-Advanced and WINNER. In order to achieve the WINNER performance targets in an economically feasible manner, the currently available radio spectrum is not sufficient. The available amount of radio spectrum identified for IMT does not permit deployment of sufficient capacity, and the fragmentation of the current spectrum bands does not permit sufficiently wide frequency channels. WINNER will have to be able to operate also on higher carrier frequencies than existing systems. This is to get enough large continuous spectrum blocks and the most efficient use of the spectrum. Spectrum sharing functionalities, such as beacon enablers, are included in the concept. [WIN2D5.9.2] To support all this one of the goals of the WINNER II project has been to participate in the preparation process towards ITU-R WRC-07 Agenda Item 1.4, in order to facilitate identification of additional spectrum for Mobile Services. Furthermore, WINNER II partners also contributed to the early phases of ITU-R process towards IMT-Advanced. Page 8 (44)

9 3. Preparations for the WRC-07 agenda item 1.4 from WINNER perspective This Chapter describes the work that has been done to prepare for the World Radiocommunication Conference Section 3.1 gives an overview of the whole process towards WRC-07. In Section 3.2 the work done within WINNER II through contributions to ITU-R WP 8F is described. WINNER II has mainly contributed on three topics: the estimation of IMT-Advanced spectrum requirements, candidate bands, and sharing studies. In conference preparatory meeting, a CPM Report is developed for the purpose of summarizing the ITU-R studies done in the preparatory work on each WRC agenda item. This work is explained in Section 3.3. Finally, in Section 3.4 the European Common Proposals are introduced and their impact on WINNER is discussed. 3.1 Overall process FIGURE 3-1 WINNER II relation to spectrum related bodies EU COMMISSION Service & Mkt Info Funding Mandates Political support WWI WINNER II ECC PT1 ITU-R WP8F CPM WRC-2007 Global Research directions WWRF CEPT Admins NOTE: This Diagram is a simplified presentation! Radio Regulations updated WINNER II partners actively participated to the WRC-07 preparatory process within the framework of agenda item 1.4 at all levels and provided a considerable amount of technical input documents addressing in particular: Spectrum requirements for IMT-Advanced taking into account the methodology and input parameters. Relevant sharing studies. Relevant information about new radio systems based on WINNER II, their performance and spectrum requirements. Those contributed in influencing the regulatory process: At European level to CEPT, especially through ECC PT1, as the European administrations are there jointly preparing the agreed European contributions to the ITU-R WP 8F and towards the WRC-07 (Agenda Item 1.4). The aim was to get the WINNER II contributions agreed on the CEPT level to become agreed European contributions to the ITU-R. WINNER II experts are then needed at the ITU to take care of the contributions at the relevant meetings. Through the individual European administrations that have been approached bilaterally. Close cooperation with national administrations facilitated their support to contributions based on WINNER II research results. Through ITU-R WP 8F and through the Conference Preparatory Meeting (CPM) done jointly by WINNER II Partners that are sector members of the ITU-R and supported through close contacts to national administrations. All these processes are illustrated in Figure 3-1. Page 9 (44)

10 3.2 WP 8F work WINNER II has been actively involved in contributing to ITU-R WP 8F work related to agenda item 1.4 of the WRC-07. In Section 3.2.1, the conclusions made in ITU-R on spectrum requirements for the further development of IMT-2000 and IMT-Advanced are presented. Section introduces the candidate bands defined for the terrestrial component of IMT-2000 and IMT-Advanced. In Section 3.2.3, the results of the sharing studies conducted in WINNER II are given. WINNER II has been active on the sharing studies between IMT-Advanced and geostationary satellite networks in the fixed satellite service (FSS) in the and MHz frequency bands Estimate conclusions This section introduces the conclusions that were made from the ITU-R study on spectrum requirements for the further development of IMT-2000 and IMT-Advanced. Further details can be found in [WIN2D5.10.2]. In ITU-R Report M.2078 the spectrum requirements are calculated for RAT Group 1 (IMT systems including their enhancements) and RAT Group 2 (IMT-Advanced) in the three different forecast years 2010, 2015 and The spectrum requirements are calculated with the methodology presented in Recommendation ITU-R M.1768 using the set of input parameter values given in 7 of [M.2078]. The spectrum calculation is based on global common market presented in Report ITU-R M.2072 which characterizes the future mobile market in the year 2010, 2015 and [M.2072] defines ranges for the market parameters while the spectrum calculations require unique values for the different input parameters. There are regional differences in the market development, i.e. in some parts of the world a particular level of market development may be reached earlier or later than in the (average) global common market. To characterize the difference in the market development and RAT Group deployment scenarios in different countries, a time shift approach is used to calculate the spectrum requirements. This approach is described in Section Section introduces the results of the ITU-R spectrum requirement estimation for the middle scenario of the time-shift approach Time-shift approach Using the unique market prediction sets for the years 2010, 2015 and 2020, the spectrum requirements can be calculated to a default scenario, called middle scenario. From these three Market predictions/ spectrum requirements two different additional scenarios, i.e. earlier and later, are derived. These additional scenarios together with middle scenario characterize the different speed of system deployment and market development in different areas. This approach and all the scenarios predict that in different time scale the predicted market will saturate to similar situation in different densely populated countries. The early identification of IMT-Advanced spectrum to support the saturated mobile market brings additional benefits. Even if the identification would take place in WRC-07, the time scale of the usage of available spectrum might differ between different administrations e.g. according different chosen time scenarios. Figure 3-2 [M.2078] shows the time shift approach on conceptual level. Some countries, wishing to implement future mobile systems as early as possible, would have a view of the system deployment as depicted in blue (top) line. This kind of deployment and market setting would refer to earlier market scenario. Some other countries would have deployment and market setting referred middle scenario shown in light blue (middle) line. This would be the default setting for spectrum requirement calculations. Those countries whose market development and/or system deployment is assumed to develop slower would have view shown in magenta (bottom) line, this is referred as later scenario. The allocation of identified spectrum might differ from market prediction. This difference is assumed to be mostly apparent between year index 2010 and Thus the trends of spectrum requirements between 2010 and 2020 are marked with dashed line. Page 10 (44)

11 FIGURE 3-2 System deployment scenarios different in time domain and consequential required spectrum (conceptual example) Spectrum requirements The spectrum requirements are calculated for RAT Group 1 and RAT Group 2 in 2010, 2015 and Table 3-1 shows the spectrum requirements for the average level of market development. TABLE 3-1 Predicted spectrum requirements for both RATG 1 and RATG 2 ( in MHz) Market setting Higher market setting Lower market setting RATG 1 RATG 2 Total y2010 y2015 y2020 y2010 y2015 y2020 y2010 y2015 y Tables 3-2 a) and b) represent the middle scenario of the time shift approach. TABLE 3-2 Ranges of predicted spectrum requirements (in MHz) a) Lower user density market development 1 network (see Note 3) 2 networks (see Note 1) 3 networks (see Note 1) 4 networks (see Note 1) 5 networks (see Note 1) RATG 1 (see Note 2) RATG RATG 1 + RATG b) Higher user density market development 1 network (see Note 3) 2 networks (see Note 1) 3 networks (see Note 1) 4 networks (see Note 1) 5 networks (see Note 1) RATG 1 (see Note 2) RATG RATG 1 + RATG Page 11 (44)

12 NOTE 1 When more than one network is present in a country the total spectrum requirement may be higher in order to account for packaging the spectrum (integer multiples of 40 MHz for RATG1). NOTE 2 The spectrum estimate for RATG1 for the year 2010 may seem high when considering current network deployments. However, the total estimation was performed using a process established by [M.1768] and technical characteristics predicted for RATG1 in the evolution of IMT-2000 technologies. Furthermore there is not enough statistical market data to predict the exact requirements for RATG1. NOTE 3 It should be noted that in [M.1768] and [M.2074] the associated terminology relating to the term Network is the term number of overlapping network deployments Candidate bands There is a need for more identified spectrum for IMT in addition to the bands already identified for IMT-2000 as shown by [M.2078], see Section It is therefore necessary to have candidate bands defined for the terrestrial component of IMT-2000 and IMT-Advanced. Some of which may need a primary allocation to the Mobile Service. In parallel with the work on the estimates ITU worked also in order to find candidate bands that could fulfill the spectrum requirements. This part of the work was also finalized and agreed at the Study Group 8 resulting in Report ITU-R M The bands of main interest for WINNER are bands that can provide large enough portions of spectrum to have several 100 MHz channels next to each other. The conclusion of this has resulted in bands between 3-5 GHz as first choice, more exactly GHz. The candidate bands from WP 8F were MHz, MHz, /862 MHz, MHz, MHz, MHz and MHz. In addition there is a statement that nomadic applications can be accommodated in the 5 GHz bands and other bands above 6 GHz if the usage is in line with certain requirements. The candidate bands and their relation to the current mobile bands, those identified already for IMT-2000, are shown in Figure 3-3. FIGURE 3-3 Current spectrum situation Tx GSM Rx GSM Unpaired band UMTS TDD Candidate band ( digital TV) UMTS band example Paired band Tx Rx GSM- GSM IMT Candidate band FDD UL Unpaired band FDD DL Candidate band IMT Candidate band Candidate band Candidate band Radiolocation FSS FSS RLAN RLAN Sharing The sharing studies related to the focused candidate bands have been performed within the framework of the ITU-R WP 8F sub working groups and have well progressed. i. Sharing studies between radiocommunication services and IMT systems operating in the MHz band [M.2110] Page 12 (44)

13 ii. Sharing studies between IMT Advanced systems and geostationary satellite networks in the fixed-satellite service in the and MHz frequency bands [M.2109] iii. Compatibility/sharing of airport surveillance radars and meteorological radar with IMT systems within the MHz band [M.2112] iv. Sharing studies related to radar systems in the frequency band MHz (contained in Document 8F/TEMP/540(Rev.1)). v. Sharing studies related to DVB applications in frequency bands below 1 GHz (contained in. Document 8F/TEMP/543(Rev.1)) These documents together represent the completion of sharing studies referred to as IMT.SHARING CANDI. Sharing activities conducted within WINNER II project focused on studies between IMT-Advanced systems based on WINNER systems parameters and geostationary satellite networks in the fixed satellite service in the and MHz frequency bands. The first WINNER sharing study results can be found from [WIN2D5.10.3]. The further sharing studies described in this deliverable address new simulations based on the analysis of: - The application of a particular mitigation technique related to the CDMA and OFDMA WINNER base station antenna in the FDD as well as TDD mode in suburban and urban environments taking into account a cellular network modeling, - An analysis of the mitigation techniques effectiveness, - The interferences created by the mobile stations together with the base stations compared to the interferences created by the base stations only, - The impact of the geographical environment. - The transmitted output power due to the dynamic down link power control. The simulations are based on generic parameters scaled to typical bandwidths technically envisaged at 4 GHz frequency, see Section Improved methodology Methodology described in [WIN2D5.10.3] has been improved and is described in this Section Based on the consideration of a cellular network modeling and base station intersite distance, the aggregate case modeling takes into account the effect of all the WINNER base station whose interference contribution is significant in the calculation. These base station are uniformly (equi-spaced) located on rings around the FSS earth station. The total sum of the interference takes into account the interference of all the base stations located up to the farthest ring of potential interference contributors. The radius of the closest ring is the required separation distance resulting from the calculation of the total sum of the interference contribution. Figure 3-4 shows the victim i.e. the FSS earth station is located in the center of the modeled WINNER system network. The improved model considers several of rings of possible interferers and the mobile stations linked to the different base stations. The closest WINNER base station is a minimum distance far away from the earth station. This distance is the radius of the first ring and represents the minimum required protection distance, denoted Dprotection. Dintersite is the distance between two base stations. The orange spots represent the mobile stations randomly distributed over the cells. The detailed calculations assumed in the network modeling are defined hereafter: Page 13 (44)

14 FIGURE 3-4 Aggregate base stations and mobile stations scenario The radius of the i th ring is: D(i)= Dprotection + ( i-1)* Dintersite The number N(i) of WINNER base station located on the i th ring is assessed according to the corresponding distance D(i) and the base station intersite distance range as following: N(i) = pi / (arc sin (Dintersite/ (2*D(i)))) Aggregate mobile station contribution This study assumes a random distribution of certain amount of mobile stations within each cell whose base station is interfering into the FSS earth station. The distance D mobile station of the closest mobile station is defined as following: D mobile station = D protection D intersite / Mitigation technique: sector disabling A possible mitigation technique could be to reduce, in the direction of the FSS earth station, the transmitting output power of base stations that are close to the protection distance. Generally, base stations have tri-sectorial antennas: a way to reduce this transmitting output power level could be to disable the antenna sector that points towards the FSS earth station. In the following simulations, the sector of certain base stations that point in the highest gain earth station lobe is switched off. This sector disabling is applied either to the base stations up to the 3 first or to the 10 first rings that are located in the maximum exclusion area 1. Both cases of CDMA and OFDMA base station antenna are studied, in the FDD as well as TDD mode. The assumed frequency reuse is Results With regards to WINNER stations transmissions in the down link scenarios, the results are given considering protection areas around the FSS earth stations so that db I/N criteria is met. The results are first given only considering the effect of aggregate BS and then the additional contribution of active MS related to the previous interfering BS is given in terms of global interference level increase defined as (IMS+IBS)/IBS. The associated Tables 3-3 and 3-5 contain only the results when the BS sector is disabled. The full active BS sectors curves are given as reference in the figures. Only the maximum and the minimum required 1 The azimuth of those BS is basically between -36 and +36. Page 14 (44)

15 protection distances are represented. The Tables 3-4 and 3-6 represent the increase of the interference level when mobile stations interference contribution is assessed Generic studies The generic studies are based on a flat terrain model. The distances derived using a flat earth model are provided to assess the maximum range of distances and should not be applied by default to define an exclusion zone around an earth station, as it is not representative of all areas around the world. The results presented hereafter cover the analysis of the effect of the aggregate CDMA and OFDMA WINNER base stations (macro and micro) for the full sectorisation or when one sector is disabled. The Figure 3-5 to Figure 3-8 provide a comparison of the required protection distances between a normal sector mode (orange curve) and the disabled sector: the green curve is related to the scenario where the 3 first rings base stations whose azimuth is between -36 and +36 are one sector disabled. The blue curve is related to the scenario where the 10 first rings base stations whose azimuth is between -36 and +36 are one sector disabled Impact of CDMA WINNER stations on FSS earth stations FIGURE 3-5 Required protection distance in the aggregate CDMA macro base station case (Generic case) Protection distance [km] 110 km 100 km 90 km 80 km 70 km one BS sector disabled up to 3rd ring full active BS sectors one sector disabled up to 10th ring 60 km 50 km Earth station elevation angle [ ] FIGURE 3-6 Required protection distance in the aggregate CDMA micro base station case (Generic case) Protection distance [km] 51 km 50 km 49 km 48 km 47 km 46 km 45 km 44 km 43 km 42 km 41 km one BS sector disabled up to 3rd ring full active BS sectors one BS sector disabled up to 10th ring Earth station elevation angle [ ] Page 15 (44)

16 TABLE 3-3 Ranges of required protection distances in the aggregate CDMA base stations (Generic case) WINNER base stations Minimum protection distance Maximum protection distance Aggregate macro BS 57 km 91 km Aggregate micro BS 42 km 46 km TABLE 3-4 Increase of global interference level created by mobile stations contribution in the aggregate CDMA base stations (Generic case) WINNER mobile stations Minimum increase Maximum increase Related to aggregate macro BS 3*10^-10 db 2,3*10^-4 db Related to aggregate micro BS 2.4*10^-6 db 2.1*10^-4 db Impact of OFDMA WINNER stations on FSS earth stations FIGURE 3-7 Required protection distance in the aggregate OFDMA macro base station case (Generic case) Protection distance [km] 62 km 60 km 58 km 56 km 54 km one BS sector disabled up to 3rd ring full active BS sectors one sector disabled up to 10th ring 52 km 50 km Earth station elevation angle [ ] FIGURE 3-8 Required protection distance in the aggregate OFDMA micro base station case (Generic case) Protection distance [km] 45 km 44 km 43 km 42 km 41 km one BS sector disabled up to 3rd ring full active BS sectors one sector disabled up to 10th ring 40 km 39 km 38 km Earth station elevation angle [ ] Page 16 (44)

17 TABLE 3-5 Ranges of required protection distances in the aggregate OFDMA base stations (Generic case) WINNER base stations Minimum protection distance (km) Maximum protection distance (km) Aggregate macro BS 51 km 55 km Aggregate micro BS 39 km 41 km TABLE 3-6 Increase of global interference level created by mobile stations contribution in the aggregate OFDMA base stations (Generic case) WINNER mobile stations Minimum increase (in db) Maximum increase (in db) Related to aggregate macro BS 1.6*10^-3 3.8*10^-3 Related to aggregate micro BS 7.7*10^-6 2.4*10^-4 Figure 3-9 shows the reduction in percent of the required protection distance when the sector is disabled up to 10 th ring compared to the full normal sector, the different coloured curves represent the results obtained with four types of WINNER base stations. FIGURE 3-9 Reduction of the protection distances in generic cases Protection distance reduction [%] 60% 50% 40% 30% 20% Aggregate CDMA micro BS Aggregate CDMA macro BS Aggregate OFDMA micro BS Aggregate OFDMA macro BS 10% 0% FSS Earth station elevation angle [ ] In the generic studies, the application of this mitigation technique has shown that the minimum protection distance ranges are reduced by up to 49 % compared with normal full active sector mode Real terrain profile data case (Application case) In the application, an example of a protection zone is assessed. The calculations are based on a real terrain profile data, in order to analyze the impact of the geographical environment in the sharing situation, compared with the generic study presented above. In this example, the earth station assumed is Bercenayen-Othe that is located in a rural area in France, therefore only the impact of macro base stations is studied. [8F/1221] The propagation model contained in Recommendation ITU-R P has been used but, in this case with the terrain profile data of the earth station location. Clutter attenuation has also been used Impact of CDMA WINNER stations on FSS earth stations Page 17 (44)

18 FIGURE 3-10 Required protection distance in the aggregate CDMA macro base station case (Application case) Protection distance [km] Aggregate CDMA macro BS 30 km 29 km 28 km 27 km 26 km 25 km 24 km 23 km 22 km 21 km 20 km full active BS sector one BS sector disabled up to 10th ring Earth station elevation angle [ ] Impact of OFDMA WINNER stations on FSS earth stations FIGURE 3-11 Required protection distance in the aggregate OFDMA macro base station case (Application case) Protection distance [km] 25 km Aggregate OFDMA macro BS 20 km 15 km 10 km full active BS sector one BS sector disabled up to 10th ring 5 km 0 km Earth station elevation angle [ ] TABLE 3-7 Ranges of required protection distances in the aggregate CDMA and OFDMA base stations (Application case) WINNER base stations Minimum protection distance Maximum protection distance Aggregate CDMA macro BS 22.8 km 29 km Aggregate OFDMA macro BS 4 km 23 km The results provided in the Figures 3-10 and 3-11 are based on the application case on a specific site and show that in real scenarios considering real terrain data, as the one applied to the French site, the calculations resulted in a protection distances range from only 4 km to 29 km (depending on the elevation angle of the earth station and the multiple access method), showing the evidence of the terrain profile significant impact into this sharing situation. The ranges are summarized in the Table 3-7. As shown in Figure 3-12, the minimum protection distances ranges could even be reduced by up to 83% compared with normal full active sector mode, depending on the access mode and on the elevation angle of FSS earth station. Page 18 (44)

19 FIGURE 3-12 Reduction of the protection distances on one application case Protection distance reduction [%] 90% 80% 70% 60% 50% 40% Aggregate OFDMA macro BS Aggregate CDMA macro BS 30% 20% 10% 0% FSS Earth station elevation angle[ ] Influence of the IMT base station e.i.r.p. The sharing studies have been based on the maximum value of the macro and micro base stations e.i.r.p., defined within ITU-R Report on sharing between IMT and FSS systems. Actually, when deploying an IMT network, the maximum e.i.r.p. for an IMT base station can vary from 59 to 35 dbm according to the type of the base station. The variation of this maximum e.i.r.p. would influence the sharing leading to the reduction of the size of the required separation distance (between this base station and a FSS earth station). This is a static setting and the reduction of the distance can be deterministically determined. Additionally, IMT advanced systems will implement the dynamic downlink power control (in CDMA and OFDMA networks). This feature will have the effect of reducing the e.i.r.p. of base stations, depending on the load of the cells, the distribution of the mobile stations within a cell and the time. However, the statistical and temporal aspect of the downlink power control has not been quantified (in terms of reduction of the distance between this base station and a FSS earth station). Both items are considered in the following sections Influence of the IMT base station maximum e.i.r.p. The value of the maximum e.i.r.p. for an IMT base station can vary from 59 to 35 dbm for the 20 MHz minimum bandwidth, according to the assumptions on the defined WINNER system. This reduction below the 59 dbm maximum e.i.r.p. value will improve the sharing between FSS earth stations and IMT base stations. Figure 3-13 shows the impact on the required distance between an FSS earth station and an IMT base station, taking into account the different types of aggregate base stations with a maximum e.i.r.p. value between 35 dbm and 56 dbm. The variation of the base stations deployment density has been taken into account accordingly to the methodology contained in the Section Page 19 (44)

20 FIGURE 3-13 Impact of the IMT BS e.i.r.p. density on protection distance reduction Protection distance reduction[%] 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Elevation angle [ ] EIRP=56 dbm EIRP=53 dbm EIRP=38 dbm EIRP=35 dbm Figure 3-13 shows the reduction in percent of the required protection distance between of a base station transmitting with the maximum e.i.r.p. compared to the same base station transmitting with a lower e.i.r.p. Four cases are represented through the coloured curves depending on the value of the e.i.r.p. The reference for the comparison is the base station whose e.i.r.p. is 59 dbm but is not drawn IMT downlink power control analysis In real operational conditions, IMT base stations do not always transmit at their maximum e.i.r.p. Downlink power control is a key feature of an WINNER radio network, which has the effect to adjust the transmit power to the minimum necessary value so as to not waste power as well as to limit intra-system interference. The DL output power transmitted depends on the DL effective load as shown on the figure below, for low and high CCH 2. FIGURE 3-14 Downlink output power depending on effective load DL Power depending on effective load DL Tx Carrier Power 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100 % DL effective load CCH = 26,7% CCH = 20,4% Figure 3-14 shows the amount of transmitted output power per carrier depending on the downlink effective load in the cell for the two cases of percentage of total output power allocated to the CCH channels. It is shown in Figure 3-14 that when the cell is 75% loaded, only 50-60% of the maximum output power is transmitted. Its use has also the effect of reducing the inter-system interference. 2 CCH are the common channels. Page 20 (44)

21 Depending on the cell coverage and capacity, the maximum value of an IMT base station power is only transmitted when the cell is 100% loaded. Downlink power control reflects the expected operational IMT deployment conditions. However, the impact of the dynamic downlink power control, on the compatibility between IMT and FSS would need to be quantified by simulations, and would have to take into account: the statistical distribution of the mobile stations in a cell (geographical and time distributions), the fact that the base station power varies temporally. However, its use has the effect of improving the sharing between IMT and FSS. The study on the influence of the e.i.r.p. shows that more realistic parameters and assumptions that would be more representative of the operational conditions would provide smaller required protection distances. The mitigation techniques that have been mentioned address the techniques that are available today and can be used to reduce the interference potential and therefore the separation distance between FSS and IMT-Advanced. Further mitigation techniques as the ones developed in the following sections are under research and can be expected to become available by the time of IMT-Advanced deployments Further mitigation techniques The first mitigation technique introduced in this section is a general method applicable for more sharing situations than IMT-Advanced and FSS Earth Stations (FSS ES), such as radiolocation and broadcasting and the second is a method more suitable for FSS ES sharing Utilization of information describing the FSS usage in a data base In areas were not all the frequency resources are utilized fully, it is possible to introduce additional services, either of the same type or other types or a mix. A way for the administrations to make possible the introduction of new services is to have a data base where all relevant information of the current service(s) using the radio resources in the area. The data base needs to be up to date and include information such as central carrier frequency, channel bandwidth, time usage etc. The more information of the systems that is available to share the radio resource the better from spectrum efficiency point of view. For different geographical locations, the IMT-Advanced systems need to be informed whether the FSS bands can be utilized. This may be performed via a specific IMT-Advanced spectrum enabler. In this situation, the IMT-Advanced system can access the aforementioned database to determine the FSS exclusion zones in its vicinity by. This concept is shown in Figure On the basis of this up to date information new services could be introduced and used in specific geographical areas. Depending on local conditions the actual available radio resources for new services may vary. The interference potential could be controlled by appropriate spectrum mask and guard bands which would avoid that adjacent channel interference potential is generated. The protection distance range can then be reduced drastically. Page 21 (44)

22 FIGURE 3-15 Sharing scenario employing Dynamic spectrum access Utilization of beacon to facilitate super high adjacent channel usage Another possibility is the use of a beacon or control information broadcasted in one or more dedicated band (i.e. outside the FSS spectrum band) so that the IMT-Advanced operator operates outside the protection distance may be used as a powerful mitigation technique. This beacon is either operated by IMT-Advanced system operators or FSS operators. The Radio Access Point (RAP) broadcasting the beacon is co-located with the ES. This case is illustrated in Figure The information contained in this beacon or control information can be measured by any IMT-Advanced Base Station. At reception of the beacon, the Base Station adapts its operation in the shared spectrum. This in turn provides a good and active protection to the FSS ES since appropriate spectrum mask and guard bands can be generated. The broadcast beacon or control information may include one or more of the following information elements: - protection distance, e.g. an IMT-Advanced Station is not allowed to radiate in an cell / sector; - power limit, e.g. a maximum power limit that can be accepted by the FSS earth station; - gradual power limit, e.g. the radio access points ensures that the transmitting power from a base station close to the earth station is low, while it may be higher for base stations further away; - indication of an alternative spectrum band - reduction in the available bandwidth; - location information. Page 22 (44)

23 FIGURE 3-16 Example of the usage of a beacon broadcasted by the RAP to facilitate the usage of the unused spectrum by the FSS ES Band segmentation To allow IMT-Advanced deployment in countries where FSS are ubiquitously deployed and where the location and operating frequencies of the earth stations cannot be determined, the band segmentation can be used. A part of MHz could be used for IMT-Advanced, the other part of this band and the whole MHz band would continue to be used for FSS operation so that IMT-Advanced and FSS systems could use separate frequency bands without any constraint of frequency or/and distance separation. FIGURE 3-17 Band segmentation 3.3 Conference preparatory meeting (CPM) The aim of the CPM Report to the World Radiocommunication Conference 2007, WRC-07, doc 3, is to summarize the ITU-R studies done in the preparatory work on each WRC agenda item, and to facilitate some level of consensus building among the administrations and ITU-R member companies, sector members, who will be involved in preparations for the WRC-07. The CPM Report is written concisely and it contains technical, operational and regulatory/procedural issues relevant to the WRC-07 Agenda available at the time of its preparation and will provide a good basis for the discussions at the Conference. The outcome from the CPM for agenda item 1.4 as seen from the WINNER and end user of communication media devices could be stated as good. This is because the results that were influenced by WINNER were represented in a relative fair manner. Both the spectrum estimate result and the candidate bands are included. However, as the CPM report only summarizes the results of the ITU preparatory studies there is not yet any assurance of enough of additional spectrum and willingness from member states to harmonize the spectrum identified for IMT and neither to find spectrum below 5 GHz. The administrations and regions will before the WRC use the CPM report as one reference for their work in producing contributions and proposals for the WRC-07 as CEPT is doing with the European Common Proposals (ECPs), see Section ECPs and possible impact on WINNER The CEPT decided the European Common proposals in the meeting of the Conference Preparatory Group (CPG) in July. The positions on the candidate bands most relevant for WINNER are: Page 23 (44)

24 MHz: The lower portion MHz is to be identified for IMT. Concerning the upper portion, MHz no position or ECP was agreed MHz: NOC (=Radio Regulations addressing this band should not be changed) Taking into account also the contributions of the other regional organizations, it seems that the most likely new spectrum band for IMT is the MHz. This would mean for WINNER that There would be room for maximum 100 MHz carriers, or a larger number of narrower carriers Co-existence with FWA systems or FSS deployed in this band in different countries would need to be addressed. The content of the ECP s may indicate what may be the result of the WRC, but things may change during the later discussions at the WRC. Page 24 (44)

25 4. ITU process towards IMT-Advanced The ITU process towards IMT-Advanced consists of two high level phases: development of the Circular Letter as described in Section 4.1 and submission, proposal evaluation and consensus building as introduced in Section Development of the circular letter The IMT-Advanced Circular Letter (full name: Circular Letter for an invitation to propose candidate radio interface technologies for IMT-Advanced ) is developed by WP 8F in the ad-hoc working group Ad-hoc Circular Letter (AH-CL) [8F/1322]. It consists of a short main body and a number of annexes (as introduced below in Section 4.1.3), which contain the actually relevant information on how proposals have to be made and evaluated Overall time schedule Figure 4-1 shows overall time schedule for the IMT-Advanced development process. The circular letter for an invitation to propose radio interface technologies is scheduled to be issue the 23 rd meeting of the WP 8F in January FIGURE 4-1 Overall time schedule of the IMT-Advanced process for the first release of IMT-Advanced detailed radio interface specification Recommendation [IMT.RSPEC] 2007 #21 # #23 #24 #25 #26 #27 #28 # #30 #31 Circular Letter for IMT-Advanced PROPOSALS Services Recommendation (IMT.SERV) Requirements related to technical system performance (IMT.TECH) IMT-Advanced WORKSHOP preliminary EVALUATION EVALUATION Revision of proposals CONSENSUS BUILDING inside & outside of ITU / Revision of proposals Evaluation criteria and methodology based on the requirements (IMT.EVAL) IMT.RADIO IMT.RSPEC Related WP 8F deliverables A number of WP 8F deliverables are developed in parallel to the CL in order to provide necessary input. WG Market and Service Aspects SWG IMT.SERV developed a Draft New recommendation IMT.SERV Framework for Services Supported by IMT. It contains high-level service-related requirements, which will be used as a basis for the development of service-related minimum requirements and evaluation criteria (input to CL Annexes 3 and 7, respectively). It has then been approved by ITU-R. The DNR IMT.TECH will contain requirements related to technical system performance (i.e., input to CL Annex 4). It is planned to be finalized at the 23 rd meeting, together with the CL itself. The evaluation methodology and evaluation criteria are developed in DNR IMT.EVAL. Since the evaluation will start only after the CL has been sent out, there is some more time to develop IMT.EVAL; it is planned to be finalized latest in the 24 th meeting of WP 8F in mid Page 25 (44)

26 4.1.3 Circular letter structure The CL will consist of a main body and 9 Annexes. [8F/1322] The development of these parts is done in parallel in different working groups as shown in Table 4-1. The main body will contain an introduction to the subject and gives an overview of which information is found in which annex. Annex 1 will give background information on IMT-Advanced. Annex 2 will describe the submission and evaluation process for IMT-Advanced candidate RITs. This includes the following items: Time schedule: the time schedule is explained in Section General process as described in the Principles Resolution [ITU-R Res.57] Detailed procedure, including activities inside and outside WP 8F, as explained in Section 4.2. Annex 3 will contain service-related minimum requirements, which will be developed based on [IMT.SERV]. At present the final nature of these requirements is not yet defined. Annex 4 will define requirements related to technical system performance. These may include requirements on cell spectral efficiency, peak data rate, cell edge user throughput, control plane latency, transport delay, QoS, mobility, handover, etc. Annex 5 will present spectrum-related operational requirements. It will include a description of the outcome of WRC-07, and the actual spectrum-related requirements. Such requirements may be that operation of IMT-Advanced should be possible in any IMT band, that the channel bandwidth needs to be scalable within certain bounds, and that IMT-Advanced needs to be able to coexist or share spectrum with co-primary or primary systems using the same band. Annex 6 will contain a technology description template of the same kind as it was used for IMT-2000 (i.e., a large table listing information that is to be provided in a submission of a candidate RIT). Annex 7 will contain the evaluation guidelines and test models, i.e., a description of the scenarios that are to be used for the evaluation of minimum requirements and a definition of how fulfilment of the requirements should be verified. Annex 8 will contain a reference list. Annex 9 will describe the IPR policy to be applied in the IMT-Advanced process. Page 26 (44)

27 Main body Annex 1 Annex 2 Annex 3 Annex 4 Annex 5 Annex 6 Annex 7 Annex 8 TABLE 4-1 Materials to be provided to AH-CL from the relevant WGs Section Title Materials to be provided Background on IMT-Advanced Submission and evaluation process, consensus building Service requirements Technical requirements Spectrum requirements Submission guidelines and template Evaluation criteria and Methodology, test model Relevant ITU-R Documents - Common text for Intro., - Spectrum text (WRC-07) Complete text based on Common text Time schedule (due dates) Complete text based on IMT.SRV Complete text based on IMT.TECH Complete text based on WRC-07 results (structure) Text, minimum requirements, Complete text based on IMT.TECH & IMT.EVAL List of ITU-R documents relevant to Annexes Responsible Group WG-SERV/SPEC (SWG-ComTxt) AH-CL WG-SRV (SWG-ComTxt) AH-Workplan AH-CL WG-SRV (SWG-Market) WG-TECH (SWG-RA) WG-SPEC (DG-SPEC-CL) WG-TECH, SERV,SPEC AH-CL SWG-Market, DG-CL-SPEC WG-TECH (SWG-EVAL), WG-SERV, TECH,SPEC AH-CL WG/DG AH-CL Prelimi. - May 30 (#22) -May 30 (#22) May 30 (#22) May 30 (#22) May 30 (#22) May 29 (#22) May 30 (#22) May 30 (#22) Final - May 28 - Jan.29 Jan.29 (#23) Jan 28 (#28) Jan.29 (#23) Jan.29 (#23) Jan.29 (#23) Jan.29 (#23) Jan.29 /Jun.16 Jan.29 (#23) Annex 9 IPR policy AH-CL Process after circular letter This section addresses the process after the CL has been issued. The CL invites for proposals for IMT- Advanced to be submitted to the ITU. These candidate radio technologies will be developed during processes which take place mostly outside of the ITU in consensus building organizations, such as 3GPP, and IEEE. Further these proposals will be evaluated by independent evaluation groups. During this phase ITU continues to monitor the processes happening outside of ITU. The proposals and evaluation reports will be submitted to the ITU for review and assessment of compliance with the minimum performance capabilities. After this further consensus building takes place inside and outside of the ITU and radio specification are developed that allow world-wide deployment of the system, Based on the proposals the ITU will develop a Radio Specification for the new air interfaces (IMT R.SPEC), which will contain the IMT-Advanced radio interfaces. The time line is depicted in Figure 4-1, and IMT-RSPEC is scheduled to be concluded at the end of meeting 31. The evaluation phase will be split in two, first a preliminary evaluation and then adjustment of the proposals and a final evaluation. The first release of IMT-Advanced is scheduled to be finalized in ITU-R WP 8F Meeting #31 in December After this updates of IMT.RSPEC are possible in order to include further, or improved radio interfaces. After this implementation of the Radio Interfaces in R.SPEC the standardization will be done outside of the ITU. Page 27 (44)

28 5. WINNER contributions to technical requirements of IMT- Advanced WINNER II contributions to technical requirements of IMT-Advanced addressed the service, technology and spectrum related requirements. Each area is described in the following text. 5.1 Service classification The service related minimum requirements for IMT-Advanced are derived from the service recommendation developed by the services group. [IMT.SERV] presents high level functional requirements to services to be delivered by IMT, and further includes service parameters and service classification of IMT. [IMT.SERV] also includes example services for IMT. The service requirements for IMT-Advanced will be derived from these high level requirements, parameters and classification during the ITU-R WP 8F meeting in January Background for service classification Within WINNER II an extensive investigation of requirements for future wireless systems has been performed [WIN2D6.11.4]. Based on these requirements, the needs of future mobile users and an evaluation of the potential performance of future wireless systems a classification of services has been developed. Generally, end users are indifferent towards quality-related issues that are not visible to them. The quality-related issues that can be observed by a user are specific to the considered service application. For example, a web browsing user perceives Quality of Service (QoS) mainly in terms of the time it takes until a web page is fully displayed after clicking on a hyperlink or entering a URL. Technically this duration results from a complex interaction of factors like throughput, packet delay, and residual bit error ratio. On the other hand the quality of a voice call mainly depends on only the residual bit error ratio. Translating service application requirements into requirements that are directly related to data transport through a wireless network commonly leads to considering a limited number of QoS attributes, such as data throughput, packet delay and/or delay variations (often referred to as delay jitter), bit/packet error rate and other similar aspects. This motivates the introduction of service classes that group together services that are similar in terms of their requirements towards a network. The service profiles have been categorized in four main groups: Conversational, Streaming, Interactive, and Background [M ]. These four main classes describe the main characteristics of the traffic in the class. The main distinguishing factor between these classes is how delay-sensitive the application is: conversational class refers to applications which are very delaysensitive while background class is the most delay-insensitive QoS class. The Conversational class has a very strict delay requirement, whereas the background class has a very lose one and preservation of the payload content is much more important (low loss rate). The Interactive class has a request response pattern, and for streaming classes it is very important to preserve the timing pattern itself, the delay requirement may vary per application. In the light of the expected future needs of the various users of wireless communication systems a further refinement of these four classes is proposed to better describe the kind of services that should be provided Service classification as contributed to IMT.SERV For the purpose of ITU and IMT-Advanced requirements the set as defined based on all the WINNER requirements was found to be too large for deriving meaningful and measurable requirements to IMT- Advanced at the service level. This section presents the service classification as developed within the WINNER II project for the purpose of high level service classification and IMT-Advanced requirements. The service classification can be found in Table 5-1. The conversational user experience class is sub divided into three service classes: Basic Conversational, Rich Conversational, and Conversational low delay. These service classes represent different performance extremes within this class, i.e. low delay, higher data rates and small packet transmissions The Basic conversational service class comprises basic services that are dominated by voice communication characteristics. The Rich conversational service class consists of services that mainly provide synchronous communication enhanced by additional media such as video, collaborative document Page 28 (44)

29 viewing, etc. Conversational low delay class comprises real-time services that have very strict delay and delay jitter requirements. In the Interactive user experience class two service classes are distinguished. Interactive services that permit relatively high delay, Interactive high delay, which usually follow a request-response pattern (e.g., web browsing, database query, etc.). In such cases response times in the order of a few seconds are permitted. Interactive services requiring significantly lower delay Interactive low delay are remote server access (e.g., IMAP) or remote collaboration. In Table 5-1 the different services from the service examples are mapped onto the eight service classes. In conversational user experience class there are three service classes. In the Streaming user experience class there are two service classes: Streaming live and Streaming nonlive. In both cases the variation or jitter of the flow is of importance, the differentiating factor between those two classes is the live or non-live nature of the content transmitted. In case of live content, buffering possibilities are very limited, which makes the service very delay sensitive. In the case of non-live (i.e., pre-recorded) content, play-out buffers at the receiver side provide a high robustness against delay and delay jitter. The background user experience class only contains delay-insensitive services, so that there is no need for further differentiation. User experience class Service class TABLE 5-1 Service classification Example services Conversational Basic conversational Voice telephony (including VoIP), Emergency calling, Push-to-talk Rich conversational Video conference, High quality video telephony, Remote collaboration, e-education (e.g., video call to teacher), Consultation (e.g., video interaction with doctor), Mobile commerce Conversational low delay Interactive gaming, Consultation, Priority service Interactive Interactive high delay e-education (e.g., data search) Consultation (e.g., data search) Internet browsing, Mobile commerce, Location based services, ITS-enabled services Interactive low delay Emergency calling, (IMAP server access), Remote Collaboration (e.g., desktop sharing), Public alerting (e.g., with feedback), Messaging (instant messaging), Mobile broadcasting/multicasting (mobile interactive personalized TV), Interactive gaming Page 29 (44)

30 Streaming Streaming live Emergency calling, Public alerting, e-education (e.g., remote lecture), Consultation (e.g., remote monitoring), Machine-to-machine (e.g., observation), Mobile broadcasting/multicasting, Multimedia Streaming non-live Mobile broadcasting/multicasting, e-education (e.g., education movies), Multimedia, Mobile commerce, Remote collaboration Background Background Messaging, Video messaging, Public alerting, (transfer RX/TX,e.g., POP), Machine-to-machine, File transfer / download, e-education (file download/upload), Consultation (file download/upload), Internet browsing Location based service Higher, enriched services exist that are difficult to capture by only one service profile, they use multiple service profiles, but are perceived by the end-user as one service. These services include for example, e- Education (e.g., conversational class for interaction, and interactive for accessing learning material), consultation (e.g., conversational class for interaction and streaming for monitoring), location based service (e.g., interactive class for accessing information, and navigation aspect). Further there are some services that are system functions including priority service, lawful intercept, and number portability. A table with typical parameters defined for the different services classes has been contributed to the IMT- Advanced process for evaluation purposes. These values can be found in Table 5-2. The parameters are derived from the example services, but the performance in these classes is not limited only to these values, values characterise typical operation in the classes and are to be used during the evaluation. Further these values are directed towards the future showing of the possibility for high data rate services. TABLE 5-2 Service Parameters defined for evaluation purposes. User Experience Class Service Class Service Parameters (Numerical Values) Conversational Basic conversational Throughput: 20 kbit/s service Delay: 50 ms Rich conversational Throughput: 5 Mbit/s service Delay: 20 ms Conversational Throughput: 150 kbit/s low delay Delay: 10 ms Streaming Streaming Live Throughput: 2 50 Mbit/s Delay: 100 ms Streaming Non-Live Throughput: 2 50 Mbit/s Delay: 1 s Interactive Interactive high delay Throughput: 500 kbit/s Delay: 200 ms Interactive low delay Throughput 500 kbit/s Delay 20 ms Background Background Throughput: 5 50 Mbit/s Delay: < 2s Page 30 (44)

31 The different services and service classes can be mapped in diagrams as shown in Figure 5-1 and Figure 5-2. The diagrams are constructed in terms of throughput and delay using the service profiles and typical parameter ranges as defined before. The diagrams show in which quadrants of the delay-throughput framework the different service classes are located. FIGURE 5-1 Diagram of the conversational and background services classes in terms of throughput and delay. Delay 2s 1s 200 ms 100 ms 50 ms 20 ms 10 ms Messaging Basic Conversational Voice telephony Emergency calling E-health Interactive game Video Messaging Remote Collaboration Video Conference Mobile commerce Background File transfer / download Rich Conversational High Quality Video e-health e-education Conversational Low Delay 50k 150k 500k 2M 50 M Throughput FIGURE 5-2 Diagram of the Interactive and Background service classes in terms of throughput and delay. 2s Delay 1s 200 ms 100 ms 50 ms 20 ms 10 ms Nav & pos High delay Interactive Location based Low delay Interactive Emergency calling Mobile Commerce Internet E-health Browsing E-Education Remote Collaboration Emergency calling Public Alerting Non-live Streaming Mobile Broadcasting E-education Live Streaming E-education E-health Mobile Broadcasting 50k 150k 500k 2M 50 M Throughput Page 31 (44)

32 5.2 Service-related requirements [IMT.SERV] defines service-related high-level requirements, which still have to be translated into minimum requirements to be included in the CL. Especially with regard to the requirement for support of a wide range of services, issues to be clarified during this process are whether associated service parameters and related values are going to be included in Annex 3 of the CL, or if this will be done in Annex 7 of the CL. Agreement has been reached that a system supporting a service class is defined as a system that is capable to support at least one user using a service with traffic characteristics as defined in the corresponding service profile. The evaluation of the minimum capability of support of a service class should be based on inspection of the fundamental technical characteristics of the proposal such as the frame structure, etc. The service-related high-level requirements defined in [IMT.SERV] are: Seamless Connectivity Seamless handover to support user mobility was stated as a requirement for IMT It remains a requirement for IMT-Advanced. In addition, IMT-Advanced should support seamless handover to at least one of the IMT-2000 family members. Requirements of various seamless services are shown in the ITU-T Recommendations [Q.1703, Y.2001,Y.2011]. It is necessary to take into consideration the factors shown below. Mobility Management As described in [M.1645], IMT is needed to continue service under nomadic, slow and high mobility conditions without conscious cooperation of the users. Interoperability When users are in a multimodal service with IMT and other systems the users do not need to be aware of the type of system the service is operating on. Constant Connection Some of the applications such as network-camera and monitoring constantly transmit data. These types of applications require constant connection services. Application Scalability For continuous service, IMT is required to maintain services despite changes of condition by adapting the data rate and/or the error tolerance of the application. Security Some applications such as Voice over IP and video telephony need to authenticate the user with the telephone number and other applications such as secure Mm-Commerce require the assurance of data integrity. IMT is required to support high security services to prevent security breaches such as eavesdropping and spoofing. Useful information concerning security is described in several Recommendations such as ITU-T Recommendations [H.235, Q1703]. Prioritization In [M.2072], applications with urgency such as emergency/disaster/disaster prediction are described. Such applications require higher priority than other applications. IMT needs to support prioritization of access to network resources. Location Many location based services need to acquire the information of the user s position. An important aspect of this capability is the ability to protect the privacy information of the user. Broadcast/Multicast As broadcast applications, broadcasting programs and IP broadcast High Definition TV and video are described in [M.2072]. There are also multicast applications for specified users such as collaborative working (application sharing) other than broadcasting services for the general public. Efficient support for point-to-multipoint transmission is required because broadcast and multicast services are expected to be an important part of an operator's service offering in the future. Page 32 (44)

33 Presence Presence allows a set of users to be informed about the availability, willingness and means of communications of the other users in a group. Usability The mobile services for IMT should be easy and convenient to use for users when they want to access desired services. So the usability may include the following two aspects: Voice Recognition Natural languages are more flexible interaction methods making IMT easier to use. So voice recognition will be a promising feature for future mobile applications. User-Friendly Human to Machine Interface Good user experience plays a crucial role in the acceptance and usability of services. Since many advanced feature and services will be provided in IMT systems, it is very important to enable a userfriendly human to machine interface. Support for a wide range of service A wide range of services are currently delivered by IMT-2000 to mobile users. Many of the service examples mentioned in Annex 1 section A.1 of [IMT.SERV] are offered. IMT is required to have the ability to offer a wide range of telecommunications services. While a specific set of services is not required, the service parameters and service classifications in Annex 1 section A.2 and A.3 of [IMT.SERV] respectively, should be used to ensure that a wide range of telecommunications services to mobile users can be provided by IMT. In order to turn the current high-level requirements into reasonable and useful minimum requirements and evaluation criteria, there is an urgent need for clarification of the high-level requirements. This is an important area for contributions to the 23 rd WP 8F meeting in January The most important high-level requirement from WINNER point of view is the requirement for the support of a wide range of services (last bullet in the list above). Overall goal of the WINNER II project is to achieve an optimal balance between meaningful requirements on the one hand and evaluation complexity and required effort on the other hand. A first clarification step of the wide range of services requirement is the service classification included in both, [IMT.SERV] and the draft CL Annex 3, but more clarification is needed. The service class profile approach developed within the WINNER II project should be used in this context. The main issues to clarify towards converting the wide range high-level requirement into a useful minimum requirement are: When is a service class considered as supported? Here, the WINNER II view is that the general approach should be based on associating a service class profile to each service class. The fulfilment of throughput and delay requirements should be checked based on inspection of fundamental characteristics (e.g., frame structure, number of data bits per symbol, etc.) of a system candidate under favourable radio conditions (i.e., errorfree radio channel, etc.). This approach aims to make sure that the regarded service profile is theoretically possible, it does not aim at defining requirements on capacity or cell-edge performance. These aspects are to be addressed in the scope of IMT.TECH. When is a set of supported services considered as a wide range? In general the support of all classes should be necessary to be regarded as supporting a wide range of services ; exceptions may be defined depending on the final test environments and scenarios. 5.3 Spectrum-related requirements This Section describes the high level spectrum related minimum requirements suggested in the framework of WINNER II to be set for the IMT-Advanced systems. These minimum requirements were contributed to ITU-R WP 8F and can be found in [8F/1295]. The need for spectrum related minimum requirements has arisen with the evolution of IMT-2000 and introduction of IMT-Advanced in different bands and with different services. The requirements include more efficient spectrum utilization to allow spectrum resources to be shared with other users or systems, and to enable harmonized use of spectrum thereby facilitating global roaming. Page 33 (44)

34 At World Radiocommunication Conference 2007, the following bands were identified for use by IMT- Advanced: MHz, MHz, MHz and MHz. There are however some conditions linked to the bands, see Chapter 6. In addition to these bands, the following bands are identified in the Radio Regulations for IMT: MHz and MHz (WARC-92, No ), 806/ MHz (WRC-2000, No A), MHz and MHz (WRC- 2000, No A). IMT-Advanced technologies are expected to cover a wide range of services by having a range of performance capabilities beyond those of IMT For the highest performance and/or capacity, wide bandwidths are needed, whereas if the coverage is emphasized narrow bandwidths can be employed. In the ideal case the IMT-Advanced bands would be globally common, however, it should also be foreseen that the actual bands made available in various countries may be different. For these reasons the IMT-Advanced candidate technologies should be able to utilize any of the bands identified for IMT as well as in all bands identified in WRC-07 for IMT-Advanced. The ability to utilize any of the bands identified for IMT-Advanced requires scalability. The system should support scalable channel bandwidths so that it can operate in a limited bandwidth, recognizing it is not possible to reach maximum performance with limited bandwidth. A minimum channel bandwidth required for the system to be able to operate is 1.25 MHz, whereas the maximum should be the bandwidth required to offer the designed maximum performance of the system. Some bands identified for IMT are shared with other primary services. IMT-Advanced in the Mobile Service (MS) should be able to share spectrum and coexist with stations of the existing primary services in the new bands identified for IMT. This could mean that IMT-Advanced may require spectrum functionalities e.g. control of the emissions into the bands shared between MT-Advanced and the other co-primary Services. Each IMT-Advanced concept should specify how the sharing is planned with other Services. In order to facilitate a more straightforward comparison of the candidate Radio Interface Technologies (RITs), a template is provided for candidate RITs to describe the technical details and the technical parameters needed to characterize the spectrum related aspects of the RIT proposals. This template is then used in the evaluation phase to get an overview and an understanding of the functionalities of the technical concept. The description template suggested by WINNER II is shown in Table 5-3 and it follows the same principles as the ones used by IMT-2000 candidate technologies [M.1225]. TABLE 5-3 Radio Interface Technologies description template A.1 Specify in which bands the RIT can be deployed and describe how this is achieved. Describe how the RIT can utilize the various bands identified for IMT- 2000/IMT-Advanced/IMT. A.2 Specify the possible operating bandwidths for the RIT. Thus, the carrier bandwidth scalability of the RIT. Minimum and maximum operating bandwidths of the system should be specified together with possible intermediate steps. Describe the solutions provided for operation on the limited bandwidth. A.3 Capability to share the spectrum with ITU-R primary Services [tbd] in the bands [tbd] [Editor s note: This should be modified in the next WP 8F meeting after the WRC 07] Describe technical solutions that enable sharing A.4 Does the RIT have other sharing capabilities in addition to the one mentioned in A.3. The capabilities could include e.g. Capability to share spectrum between similar networks Capability to share between different cell types in a network Specify what sharing capabilities RIT introduces and describe the technical solutions that enable those capabilities. A.5 Specify whether the RIT supports operation in paired or/and unpaired bands. Indicate in which test environment and in which frequency bands the RIT supports paired and/or unpaired operation. A.6 Describe the Flexible Spectrum use functionalities of the RIT. Page 34 (44)

35 5.4 Requirements related to technical system performance for IMT-Advanced radio interface In order to facilitate sufficient technical performance of IMT-Advanced to the level of WINNER performance, the following initial parameters were suggested to be included in the technical minimum requirements [8F/1292] Peak data rates IMT-Advanced should support data rates up to 100 Mbit/s for high mobility such as mobile access, and up to 1 Gbit/s for low mobility such as local wireless access. This is in line with [M.1645]. These data rates need to be mapped to the test environments, as soon as the test environments are sufficiently defined Transport delay The Transport delay or User Plane (U-Plane) delay is defined in terms of the one-way transit time between a packet being available at the IP layer in either the user terminal/base station or the availability of this packet at IP layer in the base station/user terminal. User plane packet delay includes delay introduced by associated protocols and control signalling assuming the user terminal is in the active state. IMT-Advanced should be able to achieve a U-plane delay of less than 5 ms in unloaded condition (i.e. single user with single data stream) for small IP packet, e.g. 0 byte payload + IP headers Control plane latency Control plane (C-Plane) latency is typically measured as transition time from different connection modes, e.g. from idle to active state. A transition time (excluding downlink paging delay and wireline network signalling delay) of less than 100 ms should be achievable from idle state to an active state in such a way that the user plane is established Mobility IMT-Advanced should support at least the following mobility classes. These are in line with mobility classes defined in Recommendation ITU-R M with an addition of high speed vehicular class: - Stationary - Pedestrian: up to10 Km/h - Vehicular up to 120 Km/h - High speed vehicular: up to 350 Km/h There is a need to define which mobility classes are supported by each test environment. IMT-Advanced performance related to the mobility classes defined should be as follows: - Stationary/pedestrian: Optimised system performance is expected, i.e. highest performance is achieved; - Vehicular: High system performance is expected, i.e. it is allowed that performance degrades X % from highest achieved values; - High speed vehicular: Operational system performance is expected, i.e. mobility management works (in other words connections are not lost), but data rates may degrade significantly from the highest achieved values Handover Seamless intra-system handover to support the user mobilities is required. In addition to this, seamless handover should also be possible at least to one of the IMT-2000 family members (inter-system handover) Security The achieved security level of communication should be at least at the same level as for IMT The proposal is summarized in the Table 5-4 below. Page 35 (44)

36 TABLE 5-4 Summary of minimum requirements related to technical system performance Proposed test environments Indoor Microcellular Base coverage urban High speed Peak date Rate tbd tbd tbd tbd U-Plane 5 ms 5 ms 5 ms 5 ms C-Plane 100 ms 100 ms 100 ms 100 ms Mobility classes supported Stationary, pedestrian Stationary, pedestrian Stationary, pedestrian, vehicular High speed vehicular Handover Required Required Required Required Security Required Required Required Required 5.5 Test environments and evaluation methodology For evaluation purposes it is important to define a limited set of well defined Test Environments for IMT- Advanced technology proposals. A similar approach was used in connection with the selection process for IMT The following sections derive suitable limited set Test Environments starting from [M.1645]. It describes the reference scenarios (test environments and deployment models) and channel models necessary to elaborate the performance figures of candidate radio interface for IMT-Advanced Layered approach [M.1645] sets the scene for IMT-Advanced. It covers e.g. the objectives and new capabilities of IMT- Advanced. It also addresses relationships between IMT-2000, IMT-Advanced and other systems. As part of the discussion on the last item different access systems are seen as organised in a layered structure, comprising of Distribution layer Cellular layer Hot spot layer Personal network layer and Fixed (wired) layer An illustration of the layered structure of the complementary access systems can be found in Figure 5 of the [M.1645]. According to [M.1645] the enhanced IMT-2000 and the new mobile access of IMT-Advanced will be part of the cellular layer and hot spot layer. Nomadic/local wireless access of IMT-Advanced will be part of the hot spot layer. However the Cellular layer in ITU layered structure contains both full coverage and hot spots, whereas the Hot spot layer contains both local coverage and hot spots. Such an overlap is already seen in the current and evolving mobile and wireless networks where macro cells are complemented by micro cells and pico cells where the nomadic access can include hot spots and pico cells. This suggests that instead of Cellular layer and Hot spot layers in fact three test environments should be defined. Page 36 (44)

37 Obviously a multitude of test environments for evaluation are conceivable, in particular since the IMT- Advanced air interface should provide high flexibility and covers a wide range of application scenarios. In order to allow focused work and in-depth investigations a subset test environments are proposed based on the following criteria: - Environments that are expected to be prevailing in the first roll-out phases of IMT-Advanced (e.g. initial deployment in areas where high capacity and data rates are required, operation and interworking in a multi-rat environment), - Environments spanning a different modes and parameterisation of IMT-Advanced, - Environments that include challenging system requirements, like high carrier frequencies, intercell interference, high user densities, etc. The frequencies should be the ones currently identified for IMT-2000 and the additional bands identified at WRC-07, - Environments that allow investigating critical questions in system concept and design Proposed test environments The proposed test environments [8F/1151] are the following to be derived from the ones for IMT-2000: - Base coverage urban: an urban macro-cellular environment targeting to continuous coverage for pedestrian up to fast vehicular users in built-up areas. - Microcellular: an urban micro-cellular environment with higher user density focusing on pedestrian and slow vehicular users - Indoor: an indoor hotspot environment targeting isolated cells at home or in small offices based on stationary and pedestrian users. - High speed: macro cells environment with high speed vehicular and trains. Three of these test environments are rather similar to the ones that were used for IMT-2000, Indoor Office, Outdoor to Indoor and pedestrian and finally Vehicular, and no larger modifications are needed. The new environment is high speed since subscribers nowadays also require connections in this environment. Figure 5-3 illustrates the relative positioning of three of the identified test environments. Initial focus for deployment and most challenges in IMT-Advanced system design and performance will be encountered in populated areas. However, in the evaluation the provisions for ubiquitous coverage and the associated performance also in rural areas need to be addressed. The deployment of IMT-Advanced is believed to be around year 2015 on mass market level and at that point in time the majority of countries should have a rather good coverage of pre-imt-2000 systems as well as IMT-2000 systems and its enhancements. Also the inter-working with other radio access technologies and spectrum sharing possibilities shall be key parts of the evaluation procedure. The base coverage urban test environment is intended to prove that continuous, ubiquitous, and costeffective coverage in built-up areas is feasible in the IMT-Advanced bands by the technology applying to be in the IMT-Advanced family. This scenario will therefore be interference-limited, using macro cells (i.e. radio access points above rooftop level) and still assume that the users require access to demanding services beyond baseline voice and text messages. Evaluations shall be performed by statistical modelling of shadowing effects. The microcellular test environment focuses on smaller cells and higher user densities and traffic loads in city centres and dense urban areas, i.e. it targets the high-performance layer of an IMT-Advanced system in metropolitan areas. It is thus intended to test performance in high traffic loads and using demanding user requirements, including detailed modelling of buildings (e.g. Manhattan grid deployment) and outdoor-to-indoor coverage. A continuous cellular layout and the associated interference shall be assumed. Radio access points shall be below rooftop level. The indoor test environment investigates isolated cells for home or small office coverage. Both, access point and users are indoors and a detailed modelling of the indoor environment shall be used. High user densities and requirements must be satisfied for stationary or pedestrian users. To further address the large market of small networks serving the needs of nomadic users, also ease of deployment and selfconfigurability are core parts of this scenario. The high speed test environment has a challenge in a wide-area system concept since is should allows for reliable links to high-speed trains of up to 350 km/h or cars at high velocities. Repeater technology or relays (relaying to the same wide area system, IMT-2000, or to a local area system) can be applied in the vehicle, to allow local access by the customers. Such deployments could be of course collocated in a layered approach fully benefiting from the flexibility of the IMT-Advanced interface. Page 37 (44)

38 FIGURE 5-3 Illustrative representation of three of the test environments envisaged for IMT-Advanced as seen by WINNER II These test environments are intended to cover the range of IMT-Advanced operating environments. The necessary parameters to identify the reference models include the test propagation environments, traffic conditions, user information rate for prototype voice and data services, and the objective performance criteria for each test operating environment. The test operating environments are considered as a basic factor in the evaluation process of the radio interface technologies. The reference models are used to estimate the critical aspects, such as the spectrum, coverage and power efficiencies. This estimation will be based on system-level calculations and simulations and link-level software simulations using channel and traffic models Channel models For evaluation of the minimum requirements and other relevant performance figures in the four selected test environments, a set of reliable and measurement-based channel models are needed. The channel models are described in [WIN2D1.1.1] and the models are the base for the current version of IMT.EVAL channel models, [8F/1332], Section Traffic models There are several traffic models that describes different type of traffic such as WWW, FTP, Gaming, VoIP, Streaming etc. in [WIN2D6.13.7] The models described in this section are the ones that may be used for evaluations of IMT-Advanced based on the facts that not all services will be evaluated. It will most likely be some that could prove that the proposed RIT meet the requirements. A selection from the service classes (see Section 5.1.2) for evaluation can be made. This selection can be mapped on the different test environments as illustrated in Table 5-5 for the case that basic conversation and background traffic are selected for evaluation. The table shows example values for typical services in the service classes. TABLE 5-5 Satisfied User Criteria for the different Service Classes and the Test Environments where they should be evaluated Service Class Basic Conversational Test Environments Indoor Microcellular Base coverage Urban VoIP traffic / [20] kbit/s per user / Delay < [50] ms VoIP traffic / [20] kbit/s per user / Delay < [50] ms VoIP traffic / [20] kbit/s per user / Delay < [50] ms High speed VoIP traffic / [20] kbit/s per user / Delay < [50] ms Background Full Buffer / [5]-[50] Mbit/s per user Full Buffer / [5]-[50] Mbit/s per user Full Buffer / [5]-[50] Mbit/s per user Full Buffer / [5]-[50] Mbit/s per user Page 38 (44)