Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting in the Digital Dividend Band

Transcription

1 Smart Computing Review, vol. 3, no. 5, October Smart Computing Review Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting in the Digital Dividend Band Walid A Hassan 1, Han Shin Jo 2, and Tharek Abd Rahman 1 1 Wireless Communication Centre, Faculty of Electrical Engineering, Universiti Teknologi Malaysia / Skudai, Malaysia / walid.a.hassan@gmail.com, tharek@fke.utm.my 2 Dept. of Electronics & Control Engineering Hanbat / Daejeon, Korea / hsjo@hanbat.ac.kr * Corresponding Author: Walid A Hassan Received June 24, 2013; Revised September 5, 2013; Accepted September 12, 2013; Published October 31, 2013 Abstract: The switch from analog to digital television broadcasting (DB) has freed up a newly available spectrum called the digital dividend (DD) band. This band is expected to be used for both International Mobile Telecommunication-Advanced (IMT-A) and terrestrial DB, which could lead to performance degradation for both services. In this study, a simulation model is proposed to identify the requirements for coexistence between the new system (i.e., IMT-A) and the primary system (i.e., DB) in the DD band. Our model evaluates the compatibility between the two services by considering a feasible spectrum allocation: (i) the frequency plan for DB recommended by the International Telecommunication Union (ITU) in 2006 and (ii) the European preferred harmonized spectrum for mobile channel assignment proposed in Using the Monte Carlo method, we quantify the minimum distance between the systems to ensure reliable services for a given frequency guard band. We also propose a practical guideline for efficient spectrum sharing, which will increase the efficiency of DD spectrum usage between administrations. Unlike the previous studies where the services can coexist in all adjacent channels, our results show that coexistence is possible for a limited number of adjacent channels and for a specific sharing scenario. Keywords: IMT-A, Digital Broadcasting, Interference, Co-existence, Compatibility This work was supported by the Research Management Centre (RMC), Universiti Teknologi Malaysia (UTM) under the Post Doctoral Fellowship scheme. DOI: /smartcr

2 310 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting Introduction T he introduction of digital broadcasting (DB) with high spectral efficiency for television has forced the phasing out of analog broadcasting. With advanced technologies such as coding and compression, DB can efficiently use the ultra high frequency (UHF) spectrum. In other words, while analog broadcasting needs 8 MHz of bandwidth per channel, DB can serve up to 14 channels with the same 8 MHz bandwidth. As shown in Figure 1, this efficient spectrum usage has freed up a spectrum in the UHF band called the digital dividend (DD) band. As a result, the world has begun to witness more free spectrum in the UHF band, which seemed almost impossible before. Since the Stockholm plan in 1961, the lower UHF band ( MHz) was reserved for analog broadcasting [1, 2]. At the last Regional Radiocommunication Conference in 2006 (RRC-06), all participating countries were mandated to migrate from analog to DB, and they assigned the year 2015 for the analog switch-off. The year 2015 was also assigned to countries that were not present at RRC-06 [3]. Analog Broadcasting The spectrum before 2006, occupied by analog broadcasting Digital Broadcasting Analog Broadcasting The spectrum in the transitional period, where analog and DB operates simultaneously ( /2020) Digital Broadcasting 470MHz Digital Divided 862MHz Figure 1. Origin of the digital dividend band After phasing out analog broadcasting, the remaining unused spectrum is the digital dividend (2015/2020) Frequency Plans for Terrestrial DB and Mobile Telecommunication Services in the MHz Band At RRC-06, the International Telecommunication Union (ITU) set the deployment requirements for digital video broadcasting-terrestrial (DVB-T) service in Band V ( MHz) [3]. The World Radio Conference in 2007 (WRC-07) allocated new bands for the next generation of mobile telephony technology, called International Mobile Telecommunications-Advanced (IMT-A) [4]. Moreover, resolution 794 of WRC-07 allocated the /862 MHz band to both mobile and broadcasting services on a co-primary basis in the year 2015; additionally, the resolution requires sharing studies between the two services [5]. In 2008, the European Commission mandated the European Conference of Postal and Telecommunications Administrations (CEPT) to set the requirements for harmonized spectrum allocation across European Union (EU) countries, including technical conditions for the MHz band. A detailed study was conducted for this task [6], identifying the frequency channel arrangements for the MHz band to be used by mobile services. The study was adopted in 2009 by the EU and was considered a response to the sharing study between the mobile and broadcasting services requested by the ITU at WRC-07 [7]. CEPT Report 30 [6] proposed two types of channel frequency assignments: preferred assignments based on the frequency division duplex (FDD) mode, and an alternative based on the time division duplex mode. In our study, we employ the FDD channel assignment, where the downlink (DL) and uplink (UL) consists of six channels with bandwidths of 5 MHz each, as shown in Figure 2. The spectrum assignment can accommodate scalable bandwidths of 1.4, 3, 5, 10, 15, and 20 MHz for mobile operation.

3 Smart Computing Review, vol. 3, no. 5, October Figure 2. Preferred channel arrangement [6] Since the ITU assigned the MHz band to terrestrial DB, and IMT-A will operate in the MHz band [8], it is evident that the two services must share a spectrum, which could lead to performance degradation. The objective of this paper is to quantify the possibility for compatibility between the two services and propose a practical guideline for efficient spectrum usage and reliable services based on a proposed simulation model. Related Work Recent compatibility results for the two services have been presented [9-13]. ECC148 [9] measured the DVB-T receiver performance in terms of the protection ratio (PR) and the receiver overloading threshold from long-term evolutionadvanced (LTE-A) user equipment (UE). The study was conducted to protect broadcasting services in the MHz band from the LTE-A system that will operate in the adjacent band ( MHz). Wang and colleagues [10] investigated radio interference from LTE-A base stations (BSs) and UE affecting DVB-T receivers, but reverse interference was not investigated. Zaid and colleagues [11] analyzed the co-existence of IMT-A and DVB-T BSs in the MHz band by investigating the sensitive and non-sensitive spectrum emission mask (SEM) of a DVB-T transmitter. Moreover, Shamsan and Rahman [12] investigated interference from a DVB-T BS on an IMT-A BS using the minimum coupling loss methodology for three scenarios: co-channel, adjacent channels, and zero guard bands. However, neither of these studies [11, 12] considered the receiver blocking response as part of the interference effect. Moreover, other interference scenarios such as DVB-T BS to IMT-A UE and IMT-A UE to a DVB-T subscriber station (SS) have not been investigated. Setiawan and colleagues [13] evaluated the required guard band and the separation distance between Evolved UMTS Terrestrial Radio Access (E-UTRA) and DB services in co-channel and adjacent-channel interference. However, more exact results are required since Setiawan and colleagues did not use the SEM given in the E-UTRA specifications [14]. Additionally, they did not provide any system specifications, which makes testing (or implementation) of these results impossible. Contributions Clearly, for reliable co-existence and compatibility results, a more general and exact approach is desirable. It should include the transmitter interference leakage, receiver imperfections, exact system specifications, and all potential interference scenarios. In particular, the possibility for compatibility should be investigated for various interference scenarios in rural and urban environments, such as (i) DB-BS to IMT-A BS and UE, (ii) IMT-A BS to DB-SS, and (iii) IMT-A UE to DB-SS. Additionally, the Monte Carlo method will afford more realistic compatibility results, since it randomly distributes users within the service coverage area. In order to obtain realistic and practical results, we employ feasible spectrum plans for IMT-A and DB services: the CEPT spectrum policy and the ITU digital plan, which was not fully investigated in previous studies. Adopting this approach, we evaluate the minimum separation distance and the required frequency separation to achieve compatibility between IMT-A and DB in the co-channel and adjacent channel coexistence scenarios. On the basis of our proposed model, we list the benefits and limitations of the current spectrum plan established by the CEPT and ITU, as well as the resulting design guidelines, which are the main contributions of this paper. Our co-existence results are useful for mobile operators who need more spectrums to accommodate the rapidly growing number of subscribers when adequate distance or a guard band is provided. Simulation and System Parameters Long-Term Evolution- Advanced No IMT-A system is expected to be commercially released before 2015 [15]. Although LTE release 8 fulfills some of the IMT-A requirements, LTE-A is expected to exceed the International Telecommunication Union-Radiocommunication Sector (ITU-R) time plane [2]. The LTE-A specification is thus used to represent IMT-A in our study, since it is one of the candidate technologies for the IMT-A system [8]. LTE-A will reuse the conventional LTE specification for low cost and

4 312 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting fast development. Table 1 contains the LTE-A system parameters [14, 16] of the simulation for rural and urban environments. Table 1. LTE-A parameters in rural and urban area deployment LTE-A (BS) LTE-A (UE) Parameter Rural Urban Rural Urban Pt (dbm) Operating Frequency (MHz) BW (MHz) 5, 20 Height (m) Gain (dbi) 15 0 Noise Figure (db) 5 9 Coverage (Km) Antenna Tri-Sector Ref TR v10 ACS (db) Thermal Noise (dbm) Interference Threshold (dbm) Sensitivity (dbm) Propagation Model Cell Layout -102 (5MHz) (20MHz) -108 (5MHz) (20MHz) -97 (5MHz) (20 MHz) Extended Hata Wrap around 57 tri-sector cells, uncoordinated Omni -98 (5MHz) (20MHz) -104 (5MHz) (20MHz) 93 (5MHz) (20 MHz) Number of Users Spectrum Emission Mask Receiver Blocking Attenuation Mode TS v10 (when Tx) Sensitivity mode ---- TS v10 (when Tx) (2) (3) Digital Broadcasting In our study, DVB-T represents the DB system. All the broadcasting deployment requirements, specifications, and protections from the same and other services are addressed in RRC-06 [3]. The plan proposed three types of reference networks (RN) for DB deployment in different areas. In our study, the parameters are based on RN1 and RN3 for rural and urban deployment. The reference plane configurations (RPCs) are the DB parameters and criteria for the receiver reception. RPC-1 was chosen in our study for the fixed reception mode of DVB- T as shown in Table 2. Interference Criteria The interference criterion is required to ensure co-existence between two systems in the same or the adjacent band without harmful interference. In our study, each system had its own interference criterion for the victim receiver to operate without interference. When the level of the interference (I) is below the noise with a certain margin, the receiver operates normally. However, if the level of interference rises, the thermal noise will rise, too, leading to an increase in the level of the noise floor (N) to (N+I) and an decrease in the level of the carrier-to-noise floor (C/N) to (C/N+I). If the protection criterion is considered based on an I/N value of -6 db (as a protection requirement for mobile service), this raises the noise-plusinterference level (N+I) with respect to noise by 1 db (i.e., (N+I)/N = 1 db). Other victim receiver parameters can be calculated based on the value of I/N and by knowing the system carrier-to-noise ratio (C/N), as follows: N I N I I db db db (1) I N N

5 Smart Computing Review, vol. 3, no. 5, October C C N I N I N N C C N I db db I N I I db db db db (2) (3) Table 2. DVB-T parameters in rural and urban area Deployment DB (BS) DB (SS) Parameter Rural Urban Rural Urban Pt (dbm) Operating Frequency (MHz) BW (MHz) 8 Height (m) Gain (dbi) Noise Figure (db) Coverage Radius (Km) Antenna Omni ITU-R BT Thermal Noise (dbm) Sensitivity (dbm) Propagation Model Extended Hata Model Network Type RN1 RN C/N (db) C/I (db) Reception Configuration ---- RPC 1 Spectrum Emission Mask GE Receiver Blocking Attenuation Mode ---- PR Allowed Maximum Interfering Signal (dbm) For an IMT-A system, the PR is based on ITU-R recommendations M.2039 [17] where the interference criterion between the two systems is a tolerable I/N value for the victim receiver in co- and adjacent-channel interference. Based on ITU-R M [17], the I/N for the victim receiver should be -6 db (i.e., I-N=-6 db). This means that the level of the noise should be 6 db below the thermal noise to achieve receiver protection. For DB, however, we employ different protection criteria of DVB-T depending on the type of receiver and deployment according to RRC-06 [3]. Table 2 shows the protection criteria of a DB receiver in terms C/I values for rural and urban environments. Coexistence Model Figure 3 shows a flowchart of the simulation model used here for evaluating the minimum distance for each frequency separation for each snapshot. In the initial stage, the two systems are assumed to be co-channel (i.e., f v = f it ) and coallocated (i.e., d = 0). For the second stage, the frequency of the device that suffers from interference is shifted by a certain frequency separation offset (FOS) determined by the frequency channel assignment for mobile telephony and DB. For a particular frequency separation, the probability of interference is calculated. If interference occurs, the distance between the interferer and the transmitter is increased until the interference is mitigated for that particular FOS. Then, the values of the distance and FOS necessary for co-existence are stored, the distance is reset to the initial stage (i.e., d = 0), and the frequencies are set to calculate the next FOS. The simulation ends when the frequency separation is at maximum between the interfering transmitter and the victim receiver. In the following sections, the methodology to calculate the interference is presented.

6 314 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting Start fv = fit, d= 0 End Yes fv== f_max? No fv =fv + FOS d = 0 Store d and fv d = d +0.1 P(I) = 0 % Yes No Figure 3. Simulation model flowchart to determine the minimum separation distance. Monte Carlo Methodology The Monte Carlo method is an approach that can handle analysis of complex statistical problems. The method is based on taking samples of a random process from the defined probability density function (PDF). For this reason, the Monte Carlo method is considered useful in simulating a random process such as finance, telecommunications, etc. [18]. In the area of wireless communications, the methodology is usually used to determine the compatibility between multiple systems operating in the adjacent or the same band. The results of the method have been agreed to by the ITU-R and are described in ITU-R report SM [18]. Furthermore, the method is used in many studies carried out by ITU study groups, CEPT in Europe, the Office of Communications in the UK, and the WINNER study group to assist the compatibility between different wireless communication systems that are sharing the spectrum [18]. In the Monte Carlo methodology, each trial is made up using the different variables input by the user, and the protection criterion such as C/I or I/N is calculated in each trial. After a sufficient number of trials (i.e., 10,000 snapshots), the probability of interference, P int, can be calculated as: P D E int 1 Pnon _ int IE C I where P non_int is the probability of non-interference of the victim receiver, D E is the desired signal power, and I E is the interference power. In each trial (or snapshot) the victim receiver receives the desired D E (dbm) and the interference I E (dbm) signals, which are given as: DE Pwt Gwt Gvr Lp (5) IE Pit Git Gvr Lp (6) where P wt is the power of the wanted transmitter (dbm), G wt is the gain of the wanted transmitter antenna (dbi), G vr is the gain of the victim receiver (dbi), Lp is the path loss (db), P it is the power of the interfere (dbm), and G it is the gain of the interfere antenna (dbi). I E is composed of two different sources, the unwanted emission (I E _ unwanted ) and the receiver imperfection (I E _blocking ) as follows: I I I (7) E E _ unwanted E _ Blocking (4)

7 Smart Computing Review, vol. 3, no. 5, October The Interferer s Unwanted Emission In each trial of the Monte-Carlo method the I E_unwanted is calculated at the victim receiver. The resulting interference power in the victim receiver after n number of trails is given as [19]: E _ unwanted _ i n I 10 ( En )( ) u wamted i1 I dbm log For a single i-th trial, the unwanted I E_unwanted is given as: E _ unwanted _ i emission it, vr it vr (8) I it f f G G Lp (9) where it emission (f it, f vr ) is the emission leakage from the interfering transmitter operating at a frequency offset of f it into the victim receiver operating at f vr. it_ emission (fit, f vr ) is a function of the operating frequency offset (MHz), the unwanted emission (dbm), and the reference bandwidth (MHz) as follows:,? it f f P emission f f (10) emission it vr it unwanted it vr b emissionunwanted fit, fvr 1 10 Punwanted f df a (11) where Δf =fit fvr is the difference between the frequency offsets of the interferer and the transmitter, emission unwanted (f it,f v ) is the unwanted emissions that fall into the victim receiver filter, and P unwanted (dbm) is the unwanted power related to emission unwanted (f it,f v ) which had boundaries between a = f vr -f it -(b vr/ 2) and b= f vr +f it -(b vr/ 2). Finally, b vr is the victim receiver bandwidth. Victim Receiver Blocking For each n number of trials, the interference due to victim receiver blocking is expressed as: I I n E Blocking i 10 ( dbm) 10 log 10 i 1 E _ Blocking 10 For a single i-th trial, the interference blocking is a function of frequency and is defined as: E _ Blocking _ i it it vr (12) I P G G Lp avr f (13) where avr( f) is the blocking attenuation of the victim receiver. The blocking attenuation can be calculated using two modes: the sensitivity or the PR mode [19]. Based on the receiver type, one of these modes is chosen to calculate the receiver blocking attenuation. In our simulation, the PR mode is chosen for the broadcasting receiver, whereas the sensitivity mode is chosen to calculate the receiver blocking attenuation for the mobile receiver as shown in Table 1 and Table 2. For the sensitivity mode, the block attenuation is given as [19] : avr? f ) I C max Sen vr N I where I max (dbm) is the maximum allowed interference and Sen vr (dbm) is the sensitivity level of the victim receiver. In PR mode, we employ: (14) avr( f ) I N (15) where I (dbm) is the level of the interference and N (dbm) is the noise floor level of the receiver. Both are functions of frequency difference Δf. Sharing Scenarios LTE-A (BS and UE) interference with DB-SS

8 316 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting The sharing scenario comprises an LTE-A and DB system deployed in rural and urban areas. Two different aspects are considered in our study: (i) determining the effects on DB-SSs of interference from the random distribution of LTE-A (BS or UE) with different channel bandwidths of 5 and 20 MHz and (ii) investigating the effect of DB-BSs on LTE-A (BS or UE; 5 or 20 MHz) operation. LTE-A (BS and UE) interference with DB-SS This sharing scenario is divided into two parts. The first sharing scenario is to investigate the interference from LTE-A BSs (5 and 20 MHz), and the second is to investigate the interference from LTE-A UEs (5 and 20 MHz). Each scenario assumes both rural and urban environments. DB-BS interference with LTE-A (BS and UE) The second set of sharing scenarios investigates the effects of interference from DB-BSs on LTE-A (BS and UE; 5 and 20 MHz). Both scenarios are assumed in rural and urban areas. IMT-A and DB frequency channel assignment In the mentioned sharing scenarios, the frequency channel assignment of both LTE-A and DB are considered. Figures 4 and 5 show the compatible frequency sharing scenarios between the DB and LTE-A, taking into account the two channel bandwidths of LTE-A (5 and 20 MHz), which are narrower and wider, respectively, compared with DB 8 MHz channels. In addition, the figures illustrate the UL and DL communication of the LTE-A system. These figures show the future situation in all administrations that signed Geneva Agreement 2006 (GE-06) and will use LTE-A as the IMT-A system. The figures assume that country B is using band MHz for DB services, and country A is deploying IMT-A services in the same band. Figure 4 shows LTE-A with a 5 MHz channel bandwidth. It can be seen that the MHz band can support 10 channels split into UL and DL portions, with a duplex gap of 10 MHz in between. The LTE-A channels cause/receive cochannel interference to/from DB channels and Figure 4. Sharing of MHz band between LTE-A (DL) and DVB-T In DL communication, the LTE-A device is transmitting/receiving at a frequency offset of MHz. The LTE-A system causes/receives interference to/from DB channels 60, 61, and 62, which have frequency offsets of 786, 794, and 802 MHz, respectively. The FOS between the LTE-A and DB offsets is 0.5, 7.5, and 8.5 MHz. In UL communication, the LTE-A device is transmitting/receiving at a frequency offset of MHz and can cause/receive interference to/from channels 65, 66, and 67, which operate at 826, 834, and 842 MHz, respectively. This shows that the FOS is 0.5, 7.5, and 8.5 MHz.

9 Smart Computing Review, vol. 3, no. 5, October Figure 5 shows the spectrum sharing scenario when the LTE-A system has a 20 MHz channel bandwidth. In Figure 5, the DB channels 61, 62, and 63 completely or partially overlap the LTE-A DL channel ( MHz). This leads to cochannel interference. Similarly, in UL communication, the DB channels 66, 67, and 68 completely or partially overlap the LTE-A UL channels and cause/receive co-channel interference. Figure 5. Sharing of MHz band between LTE-A (DL) and DVB-T In DL communication, an LTE-A device with an operating frequency of 801 MHz can cause/receive interference to/from DB channels 60 64, which have frequency offsets of 786, 794, 802, 810, and 818 MHz, respectively. The FOS between the LTE-A BS and DB-SS is 1, 7, 9, 15, and 17 MHz. Finally, in UL communication, the LTE-A device receives/transmits at a frequency offset of 842 MHz and, at the same time, causes/receives interference to/from DB channels These channels operate at frequency offsets of 826, 834, 842, 850, and 858 MHz, respectively. Therefore, the FOS between the two systems is 0, 8, and 16 MHz. Coexistence Model In the following subsections, the results are split according to the co-existence scenario. The following figures show the required co-existence separation distances for a given frequency separation when achieving an acceptable interference probability, P int, of 0%. In Figures 6 11, the horizontal axis represents the frequency separation between the interferer and the victim, whereas the vertical axis represents the required separation distance for that particular frequency separation. LTE-A interference with DB-SS LTE-A BS as an interferer The interference from an LTE-A BS for a DB-SS was investigated by taking into account different LTE-A channel bandwidths. Figure 6 shows the required separation distance and the frequency separation to avoid interference from an LTE-A BS with a 5 MHz bandwidth for a DB-SS deployed in rural and urban areas.

10 Separation Distance (km) Separation Distance (km) 318 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting Rural Urban Fequency Separation (MHz) Figure 6. Interference from 5 MHz LTE-A for 8 MHz DB-SS in rural and urban areas In the above figure, a frequency separation of 0.5 MHz requires a very high separation distance of 150 km in rural areas. Co-existence can be achieved with a frequency separation of 8.5 MHz (i.e., a guard band of 2 MHz) in rural areas. In urban areas, a smaller separation distance is required (37 km for 0.5 MHz separation), owing to higher clutter loss. Co-existence can be achieved with a frequency offset of 7.5 MHz (i.e., a guard band of 1 MHz) in urban areas. Figure 7 illustrates the interference scenario when considering a higher interferer bandwidth (i.e., 20 MHz LTE-A BS). 200 Rural Urban Fequency Separation (MHz) Figure 7. Interference from 20 MHz LTE-A for 8 MHz DB-SS in rural and urban areas In rural areas, the interference is intense, with a frequency separation of 1 MHz, since it requires a separation distance of 220 km. Coexistence can only be achieved with a frequency separation of 15 MHz (i.e., a 1 MHz guard band) and above. In an urban area, the required separation distance is 40 km for a frequency separation of 1 MHz. In addition, co-existence can be achieved with a frequency separation of 15 MHz or above. On the basis of the above results, it can be concluded that the deployment of LTE-A in urban areas is more feasible than in rural areas. Moreover, the higher interferer channel bandwidth (20 MHz LTE-A) caused more interference. This is attributed to the fact that an interferer with a lower bandwidth requires a larger separation distance and higher frequency separation. It can be seen that coexistence can be achieved in all sharing scenarios, with a minimum guard band of 2 MHz in rural and urban areas. LTE-A UE as an interferer

11 Separation Distance (km) Smart Computing Review, vol. 3, no. 5, October When considering an LTE-A UE as an interferer (i.e., UL), the simulation results show that co-existence is achieved in all sharing scenarios in rural and urban areas. This is attributed to the fact that the LTE-A UE height is 1.5 m, which is considered low relative to a DB-SS (10 m height). This height difference can mitigate interference resulting from an LTE-A UE. DB-BS interference with LTE-A LTE-A BS as a victim The results of co-existence between a DB-BS and LTE-A BS (5 and 20 MHz) in UL communication are shown in Figure 8 and Rural Urban Fequency Separation (MHz) Figure 8. Interference from DB-BS for 5 MHz LTE-A in rural and urban areas In rural areas, the LTE-A BS needs to be 150 km away from the DB-BS for a frequency separation of 0.5 MHz. Coexistence is achieved with a frequency separation of 7.5 MHz (i.e., a guard band of 1 MHz) or above. However, in urban areas, a frequency separation of 0.5 MHz requires a 37 km separation between the DB-BS and LTE-A BS. Similarly, co-existence can be achieved with a frequency separation of 7.5 MHz (i.e., a guard band of 1 MHz) or above. Figure 9 shows that in order to avoid co-channel interference between the systems, a separation of 200 and 100 km is required in rural and urban areas, respectively. Co-existence can be achieved with a frequency separation of 16 MHz (i.e., a 2 MHz guard band) in both areas. LTE-A UE as a victim receiver Figures 10 and 11 show the co-existence requirements for a DB-BS and LTE-A UE (5 and 20 MHz). In the above figure, a frequency offset of 0.5 MHz requires a separation of 60 km and 30 km to protect the LTE-A UE (5 MHz) in rural and urban areas, respectively. In this sharing scenario, co-existence cannot be achieved even with a frequency separation of 8.5 MHz. However, when the LTE-A UE has a higher bandwidth (i.e., 20 MHz), co-existence can be achieved in rural and urban areas with a frequency separation of 15 MHz (i.e., a 1 MHz guard band), as shown in Figure. 11. Generally, from the above results, it can be concluded that the required separation distance is less in urban areas. Moreover, the higher the victim channel bandwidth (20 MHz LTE-A), the lesser the separation distance required. Finally, co-existence can be ensured in all sharing scenarios with a guard band of 2 MHz or above in rural and urban areas, except in the case of interference from a DB-BS affecting an LTE-A UE (5 MHz) in a rural area.

12 Separation Distance (km) Separation Distance (km) Separation Distance (km) 320 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting Rural Urban Fequency Separation (MHz) Figure 9. Interference from DB-BS for 20 MHz LTE-A in rural and urban areas Rural Urban Fequency Separation (MHz) Figure 10. Interference from DB-BS for 5 MHz LTE-A in rural and urban areas Rural Urban Fequency Separation (MHz) Figure 11. Interference from DB-BS for 20 MHz LTE-A in rural and urban areas

13 Smart Computing Review, vol. 3, no. 5, October Conclusion This paper described the compatibility between IMT-A (represented by LTE-A) and terrestrial DB (represented by DVB-T) when they share the same or adjacent frequency channels. We introduced a simulation model that utilizes the spectrum allocation policies proposed by CEPT, and the digital plan assigned by the ITU for DB frequency allocation and deployment. The simulation results mainly show that co-existence of the two services is impossible in the co-channel scenario and, in some situations, in adjacent channels. These results differ from previous studies [9-13] that found that the two systems can coexist in all adjacent channel-sharing scenarios. The channel frequency assignment for both mobile and broadcasting services must be considered in any sharing study between the two services for more realistic results. Our model can be adopted to set spectrum sharing guidelines and recommendations for deploying IMT-A and terrestrial DB in the DD band based on adequate frequency and distances between devices utilizing the two different technologies. Finally, the results motivate the shared usage of the MHz band for IMT-A and DB services in cases where the two services are operating simultaneously in neighboring countries. References [1] B. Modlic, G. Sisul, M. Cvitkovic, Digital dividend - Opportunities for new mobile services, in Proc. of 51st International Symposium ELMAR-2009, Sept [2] V. P. Kalogirou, E. D. Nanou, N. C. Capsalis, T.-H. N. Velivasaki, Compatibility of DVB-T services and IMT-2000 compliant mobile telecommunications in the UHF band of MHz, in Proc. of 9th International Conference on Telecommunication in Modern Satellite, Cable, and Broadcasting Services, pp , Oct Article (CrossRef Link) [3] RRC-06, Final Acts of the Regional Radiocommunication Conference for Planning of the Digital Terrestrial Broadcasting Service in Parts of Regions 1 and 3, in the Frequency Bands MHz and MHz (RRC- 06), ITU, Geneva, July [4] WRC-07, Final acts WRC-07, Geneva, ITU, [5] Resolution 794 (WRC-07), Studies on the use of the band MHz by mobile applications and by other services, ITU, [6] CEPT Report 30, The identification of common and minimal (least restrictive) technical conditions for MHz for the digital dividend in the European Union, European Conference of Postal and Telecommunications (CEPT), [7] H. R. F. Karimi, Lapierre G., Fournier E., European Harmonized Technical Conditions and Band Plans for Broadband Wireless Access in the MHz Digital Dividend Spectrum, in Proc. of 2010 IEEE Symposium on New Frontiers in Dynamic Spectrum, Apr Article (CrossRef Link) [8] D. Parkvall, LTE-Advanced - Evolving LTE towards IMT-Advanced, in Proc. of the 68th IEEE Vehicular Technology Conference, Sep Article (CrossRef Link) [9] Erodocdb, ECC148 Measurements on the performance of the DVB-T receivers in the presence of the interference from the mobile service (especially from LTE), Marseille, E.a. CEPT, [10] W. Weidong, et al., Analysis of interference from digital Terrestrial Television Broadcast to LTE TDD in Digital Dividend Spectrum, in Proc. of 2nd IEEE International Conference on Network Infrastructure and Digital Content, Sep Article (CrossRef Link) [11] Z. A. Shamsan, T. Abd. Rahman, M. R. Kamarudin, Coexistence and Sharing between IMT-Advanced and DVB-T Services at MHz, in Proc. of the 9th WSEAS international conference on Telecommunications and informatics, [12] Z. A. Shamsan, T. A. Rahman, T-DVB Services Coexistence with IMT-advanced Service, in Proc. of Progress in Electromagnetics Research Symposium, [13] D. Setiawan, D. Gunawan, D. Sirat, Interference Analysis of Guard Band and Geographical Separation between DVB-T and E-UTRA in Digital Dividend UHF Band.Icici-Bme, in Proc. of 2009 International Conference on Instrumentation, Communication, Information Technology, and Biomedical Engineering, pp , Article (CrossRef Link) [14] 3GPP TS v9.2.0, Technical Specification Group Radio Access Network; Base Station (BS) radio transmission and reception (Release 9), 3GPP, [15] Z. A. Shamsan, T. B. A. Rahman, A. M. Al-Hetar, Point-Point Fixed Wireless and Broadcasting Services Coexistence with IMT-Advanced System, Progress in Electromagnetics Research, vol. 122, pp , Article (CrossRef Link) [16] 3GPP TS v9.2.0, Technical Specification Group Radio Access Network;User Equipment (UE) radio transmission and reception (Release 9), 3GPP, 2009.

14 322 Hassan et al.: Simulation Model for Compatibility between LTE-Advanced and Digital Broadcasting [17] ITU-R M , Characteristics of terrestrial IMT-2000 systems for frequency sharing/ interference analyses, ITU, [18] SEAMCAT handbook, European Communication office (ECO), [19] ERC 68, Monte-Carlo Simulation methodology for the use in the sharing and compatibility studies between different radio service or systems, Dr. Walid A Hassan (Iraqi) is a Post Doctoral Research Fellow, Wireless Communication Centre (WCC), Faculty of Electrical Engineering (FKE), Universiti Teknologi Malaysia (UTM). He obtained his PhD from University Technology Malaysia in He earned his master s degree from the faculty of engineering, University Technology Malaysia. He obtained his BSc from Garyounis University in the faculty of electrical and electronic engineering (telecommunications major), Benghazi, Libya. His research interests include spectrum sharing, wireless communications co-existence and compatibility, as well as cognitive radio spectrumsharing methods. Dr. Han-Shin Jo is an Assistant Professor with the Department of Electronics and Control Engineering, Hanbat National University, Korea. He was a Postdoctoral Research Fellow in the Wireless Networking and Communications Group, in the Department of Electrical and Computer Engineering, University of Texas at Austin, from Dr. Jo developed LTE systems for Samsung Electronics in He received his BS, MS, and PhD degrees in Electrical and Electronics Engineering from Yonsei University, Seoul, Korea, in 2001, 2004, and 2009, respectively, and he received the 2011 ETRI Journal Award. His research interests include small cells, heterogeneous networks, wireless ad-hoc networks, stochastic geometry, and wireless broadband transmission. Dr. Tharek Abd Rahman is a Professor in the Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM). He obtained his BSc in Electrical & Electronic Engineering from the University of Strathclyde, UK, in 1979, his MSc in Communication Engineering from UMIST Manchester, UK, and his PhD in Mobile Radio Communication Engineering from the University of Bristol, UK. He is the Director of the Wireless Communication Centre (WCC), UTM. His research interests are radio propagation, antenna and RF design, and indoor and outdoor wireless communications. He has also conducted various short courses related to mobile and satellite communications for the Telecommunication Industry and Government body since He has teaching experience in the area of mobile radio, wireless communications systems, and satellite communications. He has published more than 120 papers related to wireless communications in national/international journals and conferences. Copyrights 2013 KAIS