White Paper. Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges

Transcription

1 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges

2 2/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges Contents 1. Introduction 3 2. Challenges for Wireless Backhaul and Transport 4 3. Leveraging E-Band Systems for Backhaul 5 4. E-Band Technology Characteristics 6 5. E-Band Regulatory Status 7 6. Conclusion 9 7. Glossary 10

3 3/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges 1. Introduction All signs show that the explosive growth of fixed and mobile IP-based broadband services observed in the first decade of the 21 st century will continue unabated throughout its second decade. While technological creativity engenders the digital world of cyberspace, the forces of the market engage in a race to exploit its potential for profit. Under the market drive, cyberspace is continuously invented, transformed and expanded, adapting to profound socio-economic developments, as well as, instigating them. Within the framework developed by international and national telecoms regulation, the fierce competition among the cyberspace market players, fighting for the rewards of this new land of opportunity, accelerates the development of its underlying technologies in a true Darwinian sense. Broadband access and transport technology generations, which form part of the fabric of cyberspace, evolve at a rapid pace and enable ever more complex and demanding multimedia applications and communication services. All parts of communications network infrastructure are rapidly undergoing a transformation in capacity and functionality. In particular, capacity requirements have been growing at an exponential pace. In the core part of the network Optical fibre transmission technology, capable of Tbit per second capacity per fibre, has evolved to be the only medium capable of supporting the multimedia IP-based traffic capacity requirements. At the same time the use of optical fibre is becoming mandatory in many parts of the aggregation network, as well as being considered as the end game for the delivery of fixed broadband services up to the user premises. The huge capacity increases imposed on the core networks are the result of increase in the number of broadband users and the rapid progress in broadband access technology capabilities. Traditionally, a mix of technologies other than fibre, wireline and wireless, has been utilised to deliver the fixed broadband services to the user premises. In the field of fixed access networks, DSL technology rapidly progressed from ADSL to ADSL2+ and from there to VDSL and VDSL2. Additionally, in hybrid fiber-coaxial (HFC) networks cable access technology progressed up to Data over Cable Service Interface (DOCSIS) standard 1 to standard 3. All these technologies are enabling end-user capacity to reach from 50 to 100 Mbps. The most impressive development though, in the area of access systems, are the advances in performance that mobile and fixed wireless access systems have demonstrated in the last decade, while serving a continuously growing population of billions of users. Although initially, 2G and 3G generation mobile wireless systems were lacking in the raw throughput compared to conventional fixed broadband access systems or even fixed wireless access, the relentless progress in broadband wireless access technology fuelled by the increase in demand for rich media content and bandwidth hungry applications has driven the development of 4G, high capacity, low latency mobile broadband access standards. Systems based on 3.5G HSPA+ or 4G LTE and WiMAX technologies, are currently capable of delivering more than 10 Mbps per user in the field. In the pipeline, ITU s IMT-Advanced compliant mobile wireless standards, such as WiMAX Release 2 and LTE-Advanced, promise peak access speeds in excess of 100 Mbps and up to 1 Gbps available before The backhaul and aggregation networks, in between the access part and the core part of the network, are of critical importance to operator profitability due to their size and their contribution to the total capital and operating cost of broadband networks. These network parts, due to practical and financial reasons have traditionally employed a mix of transport technologies, wireless being one of the most successful and widely deployed, particularly outside of the USA. This paper discusses the developments in the field of wireless backhaul and transport and how the wireless transport technologies available in the GHz & GHz frequency range, also known as E-Band, can be leveraged to enable wireless, remain a technologically and financially competitive option to satisfy the evolved requirements.

4 4/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges 2. Challenges for Wireless Backhaul and Transport The current and future IP-based 4G air-interface capacity and deployment features introduce number of challenges for backhaul and aggregation networks: Increased capacity per base station, arising from the advanced multi-dimensional (Frequency, Time, Space) signal processing techniques and the use of wider channel bandwidths of the broadband wireless access air-interface. Dense placement of base stations, of the order of a few hundred meters, particularly in urban environments. This is needed to enable ubiquitous, high-bandwidth and consistent user experience under fixed and mobile conditions. Apart from the dense Macro BS deployment model 4G necessitates, the use of a multitude of additional base station form factors: Micro, Pico, Fempto. Co-existence of 2G and/or 3G with 4G systems for the most part of next 10 years in, at least a significant, subset of sites. As the digital radio market is strongly driven by the developments of the mobile base station infrastructure market, wireless technologies in the conventional microwave bands, 6 GHz to 38 GHz, have been closely following and adapting to the technological developments of the last decade by: Qualitatively, by evolving to support the transformation of traffic from predictable TDM-based to statistical highly variable Ethernet / IP-based. Quantitatively, by increasing the transport capacity and lowering the cost-per transported bit. Fixed wireless radios at microwave frequencies from 6 to 38 GHz are widely used in Point-to-Point (PtP) and Point-to-Multi Point (PtMP) configurations for data transmission offering a full range of interface types ranging from TDM / ATM E1 s to STM1 / STM4, as well as, Fast Ethernet and GbE. The link capacity of these systems is constrained by the relatively small channel size that is imposed by regulation in the microwave frequency bands; For example, currently, the maximum allowed channel size is 56 MHz according to the widely adopted European regulatory standards. Despite this restriction, due to continuous advances wireless system technology, such as high order modulation formats (256QAM now, 512QAM or higher in the future), polarisation multiplexing (PM) with cross-polarisation interference cancellation (XPIC), Radio link aggregation (RLA), native packet transport introduction, packet header suppression (PHS)/compression, such systems are now available with useful capacities of 800 Mbps or more per frequency channel. Furthermore, nodal equipment integrating multiple modems in compact form factor indoor units and employing multiple aggregated channels can provide multi Gbps inter-site connections.

5 5/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges 3. Leveraging E-Band Systems for Backhaul Notwithstanding the significant and continuing progress in conventional microwave technology, the characteristics of 4G system deployment increase the pressure in the following particular backhaul configuration features and issues: Particularly high density of backhaul links especially in urban areas, a large percentage of which involves small distances of less than a kilometre. Depending on amount of spectrum used for access, type of base station (macro, micro, pico) and its deployment environment, a typical 30 Mbps to 150 Mbps Ethernet/IP backhaul capacity per cell is required. Very high capacity (1 Gbps or more) trunk links or rings aggregating traffic from multiple Base stations. Management of link capacity-affecting interference arising from the high concentration of short links combined with the exhaustion of traditional microwave frequency channels used to implement those links. Flexible and cost effective deployment capabilities to support various form factor Base station types, especially Micro and Pico base stations for which low footprint and compact configurations are critical in ensuring practical placement and minimum real estate expenses. E-Band millimetre wavelength radio technology can be leveraged successfully to address this backhaul feature mix. After year 2000, the millimetre wavelength radios have reached the technological maturity and cost point, which enables their practical deployment. Today, compact E-Band spectrum systems, operating in the GHz & GHz frequency range, can be used to provide links with high and very high transport capacities. Additionally, the addition of E-Band links allows more flexibility in the channel planning /interference management of the microwave links operating in the 6-38 GHz bands. The abundant bandwidth and the flexible channelisation regulation of E-Band, enables the utilisation of wideband channels, even up to 5 GHz in bandwidth, to achieve uniquely high wireless throughputs in a technically simple and economical way. Options from 100 Mbps to more than 1 Gbps full duplex per link capacity are commercially available, while, in the future, throughput is expected to reach 10 Gbps by the combined use of high channel bandwidth and higher order modulation schemes. It is important to note that E-band systems are native packet radios, with characteristics that align with service definitions and features as specified in MEF, IETF, 3GPP and ITU recommendations. Based on these features, E-Band systems can be leveraged to satisfy present and future requirements for backhaul and aggregation network traffic transport. The next paragraphs explore in more detail the characteristics and boundaries of applicability of E-Band systems.

6 6/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges 4. E-Band Technology Characteristics The propagation of electromagnetic radiation of the millimetre-wavelength band in the atmosphere is generally accompanied by higher losses relatively to the, conventional, microwave radiation propagation. The high frequency of the millimetre wavelength, E-Band systems, results in higher free space propagation losses and significantly higher sensitivity to rain precipitation compared to conventional microwave systems. Both these elements impact the link power budget and reduce the range of an E-band system relative to that of a conventional microwave of equal link budget. Nevertheless, E-Band systems technology can partially compensate the disadvantage imposed by physics of radiation transmission. The brute force approach of using wide bandwidth channel enables the delivery of the very high capacities with simple, low order, modulation format. Low order modulation format, in turn, relaxes the amplifier linearity requirements and enables higher transmit power. Today, transmit power at antenna port of over 20dBm is achievable. This is important in relation to achieving the necessary link power budget values, which enable practical link distances. In addition, millimetre wavelength systems are benefiting from high antenna gain values) even at relatively small antenna sizes: more than 43dBi / 51dBi for 30 cm / 60cm antenna radii respectively). This facilitates the configuration of practical-range systems with small diameter antennae, which can be deployed in a flexible and cost-effective way. It should be pointed out that millimetre wavelength systems in the E-band are relatively immune to absorption by atmospheric gasses, as well as, other atmospheric scattering agents such as fog, clouds and airborne particles that are characterised by micrometer rather than millimetre dimension scales. Effective link lengths of PtP E-Band systems under Line-of-Sight conditions can vary, depending on the required capacity and rain zone, from about 500 meters up to several kilometres. Fig. 1 shows typical ranges that can be achieved by a top of the range E-Band system for a very high capacity link, 1 Gbps full duplex, in two different rain zone areas, Athens and Moscow. As can be seen in the figure, availability objectives are impacting the achievable ranges, which nevertheless are over 1 km for high link availability even with 30 cm antennae. It is noted that for lower throughputs such as a few hundred Mbps, the link lengths can be further increased. These results demonstrate that E-Band high capacity link lengths are very practical in real life deployment scenarios Link Length (km) Athens / 30cm antenna Athens / 60cm antenna Moscow / 30cm antenna Moscow / 60cm antenna Availability (%) Figure 1: Ranges for a 1 Gbps link for two different rain zones and two different antenna sizes Vs required link availability

7 7/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges Another important feature is that the steep propagation loss curve and narrow radiation beam width of E-band systems facilitate interference management in a high link density environment, such as urban environment. As millimeter wave radiation is confined to very narrow beamwidths of the order of the fraction of a degree and it is attenuated strongly with distance interference is minimised from a link to its nearby links. Therefore, E-Band frequency links can be deployed more densely than the conventional microwave frequency links. On the other hand, E-Band links can be introduced to partially substitute microwave frequency links, reducing their density and alleviating interference in the below 38 GHz frequency bands. As a result, several country spectrum regulators view E-Band GHz links as a means for addressing microwave-frequency congestion issues that are becoming increasingly common in major urban areas as the number of cellular base station sites grows. As a future-orientated, 4G-enabling technology, E-Band systems are designed from the ground up as low latency/jitter, high capacity native packet radios in fully outdoor configuration. Native support for Carrier Ethernet-based networking, QoS and OAM features is inbuild, while, the ability to support other types of transport, such as TDM E1s and STM-1, over packet through Pseudowire Emulation Service according to IETF PWE3 or MEF 8 can be accomplished by additional indoor pseudowire units. Transport of synchronisation, if required, can be supported through the standard packet-based standards such as Synchronous Ethernet, Precision Timing Protocol ( ), NTPv4. In an alternative backhaul architecture scenario requiring TDM and Ethernet/IP transport, the E-Band packet radio may be placed in a mixed 2G/3G/4G base station location as an additional backhaul system dedicated to transporting the Ethernet/IP-based traffic, while legacy TDM traffic keeps being transported over the legacy backhaul system. Therefore, E-Band radios are compatible with all transport technologies and backhaul architectural options in the present and the future. E-band systems can be deployed in protected linear configuration, as well as, ring and mesh (subject to Line-of- Sight condition) configurations. In this way, they can ensure carrier class survivability features necessary for their adoption in availability sensitive applications. The all-outdoor configuration, low intrinsic power consumption and flexible small form factor of E-Band systems reduce the required installation footprint and power supply requirements minimising their associated costs. 5. E-Band Regulatory Status The E-Band technology maturity achieved within the first decade of 2000 and the microwave frequency band congestion drove numerous international and national regulatory bodies all over the world to effect regulation regarding the GHz & GHz frequency range spectrum. The USA and then Europe were the first to respond launch regulation around year 2005, while many other countries have followed and opened the E-Band frequencies. In general, channel allocation and duplexing within the E-Band has been determined to be quite flexible. Although guidelines for basic channel arrangement within the E-Band are provided, regulation allows the concatenation or subdivision of the recommended basic channel sizes. For example, in Europe CEPT/ECC/ Recommendation (05)07, defines the channel arrangement for the 71 GHz to 76 GHz and 81 GHz to 86 GHz bands as follows: Within each 5 GHz bandwidth, nineteen 250 MHz channels are defined, with a 125 MHz guard band at the bottom and top of each 5 GHz band. Aggregation of any number of channels, from 1 to 19, is permitted. The specified channels may be used for Time Division Duplex or Frequency Division Duplex (FDD). In particular, FDD duplexing can be specified with a 10 GHz duplexing interval between GHz & GHz or within each of the two 5 GHz bands with 2.5 GHz FDD duplexer spacing. In the USA, basic channel segment is defined

8 8/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges to be 1.25 GHz allowing, however, basic channel aggregation up to 5 GHz and subdivision of the segments into narrower bandwidths is allowed. Due to the interference-mitigating features of the E-band radiation propagation, discussed about in the previous paragraph, the several regulatory bodies have chosen to adopt a more relaxed, than the conventional, less time consuming and costly frequency coordination / licensing schemes, called light licensing, summarised as follows: According to the Light licensing regime the position and characteristics of the link stations are recorded on a database on a first-come first-served basis, with responsibility for subsequent users to ensure the compatibility with previously notified stations. The choice of the appropriate assignment method and traditional or light licensing regime remains a decision for national administrations. The license fees under the light licensing scheme are significantly lower than the fees demanded for licences in the conventional microwave bands. Furthermore the speed of approval is significantly higher than the process followed for microwave band spectrum. Such features are very conducive to the adoption of E-Band technology for backhaul and any other fixed transport application. It should be noted that the bands GHz and GHz are used in some countries by other services or applications than fixed services PtP links. For example, the bands GHz and GHz have been identified as NATO Type 3 bands, i.e. for possible military use in NATO Europe. Nevertheless, the European Table of Frequency Allocations and Utilisations (ECA, ERC Report 25, footnote EU27) mentions that The band can be shared between civil and military users according to national requirements and legislation. The same is stipulated for protection of radio astronomy application within the E-Band. These are taken into account by administrations wishing to use whole or parts of the frequency bands GHz and/or GHz for commercial PTP links.

9 9/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges 6. Conclusion This paper discussed how the mature E-Band, millimeter wavelength, radio technology can be combined with the traditional microwave systems in the backhaul and aggregation network to provide significant benefits in terms of enhancing and future-proofing the performance of wireless backhaul. The high capacity achieved at practical ranges and link availability values, the rich networking features, the deployment and operational flexibility, the ease of interference management and the favourable regulatory framework render, today, the E-Band as an important part in a broadband operator s strategy for an effective, efficient and future-proof high capacity backhaul and aggregation network. It is worth noting at this point, that E-Band systems can be used for a multitude of other applications that combine relatively short distance and high-capacity requirements: xdsl backhaul, campus LANs, construction site, shipping port area communications systems, storage connection back-up, WiFi hotspot backhaul, and the list goes on. The technology is now mature as it has been under commercial field deployment for more than 5 years. Many operators are expressing their interest and have included E-Band systems in their testing programs. As part of the long standing Intracom Telecom commitment to remain on top of market developments in wireless backhaul and transport, its wireless product line includes a top of the range millimeter wave E-Band wireless platform. Given that there is no single wireless technology type that can optimally fit all cases and requirements, Intracom Telecom has developed a comprehensive wireless product portfolio to span across a multitude of types and categories. This portfolio comprises radios spanning the conventional licensed frequency bands from 6 to 38 GHz, as well as, E-Band solutions and includes: Point-to-Point links, High Density Nodal and Point-to-Multi Point systems. Furthermore, in terms of transport types TDM/ATM (E1 to STM-1), Hybrid TDM / Ethernet and native Ethernet are supported, with scaleable capacities from 34 Mbps to more than 1 Gbps. Intracom Telecom wireless system types can coexist synergistically within the network, following a best-fit minimum-cost approach. The versatile wireless system mix is seamlessly integrated under an advanced umbrella management system. The Intracom Telecom product portfolio, combines the high capacity, multiservice WiBAS PtMP platform, the highly scaleable hybrid TDM /Ethernet INTRALINK PtP and the OmniBAS PtP and high density nodal pure Ethernet radio platform operating in microwave bands and the OmniBAS -E operating in the millimeter wavelength, E-Band. Sharing state-of-art operation and advanced performance, all systems are managed by the same unified network management suite - uni MS, hence they can appear as a consolidated network in the Network Operations Centre (NOC). Intracom Telecom is the only vendor that can offer a unified mixed PtMP / PtP solution.

10 10/11 White Paper Leveraging E-Band Spectrum Radios to Meet Present and Future Wireless Backhaul Challenges 7. Glossary ADSL ATM DOCSIS FDD / TDD HSPA HFC IETF IMT IP ITU LTE MEF MPLS MW OAM ODU PHS PM PtMP PtP PWE3 RLA QAM QoS RAN STM TDD TDM UMTS VDSL WiFi WiMAX XPIC Asymmetrical Digital Subscriber Line Asynchronous Transfer Mode Data over Cable Service Interface Frequency / Time Division Duplex High Speed Packet Access Hybrid Fibre-Coaxial system Internet Engineering Task Force International Mobile Telecommunications Internet Protocol International Telecommunications Union Long Term Evolution Metro Ethernet Forum Multi Protocol Label Switching Microwave Operation Administration and Maintenance Outdoor (Radio) Unit Packet Header Suppression Polarisation Multiplexing Point-to-Multi Point Point-to-Point Pseudowire Emulation Edge to Edge Radio Link Aggregation Quadrature Amplitude Modulation Quality of Service Radio Access Network Synchronous Transport Module Time Division Duplex Time Division Multiplexing Universal Mobile Telecommunications System Very high speed Digital Subscriber Line Wireless Fidelity Wireless interoperability for Microwave access Cross-polarization Interference Cancellation

11 11/11 White Paper Leveraging E-Band spectrum radios to meet present and future wireless backhaul challenges Intracom Telecom Regional Contacts Europe 19.7 km. Markopoulou Ave., Peania, Athens Greece tel.: fax: Russia & CIS 16 Krasnoproletarskaya Str., Bldg.1, Entr.3, Moscow, Russia tel.: fax: America 3885 Crestwood Parkway Suite 100, Duluth, GA USA t: f: Middle East & APAC Building No. 3, Office No. 204 P.O. Box , Dubai Internet City, Dubai United Arab Emirates t: f: Africa Unit 18 Mezzanine, Oxford Office Park 3 Bauhinia Street, Highveld Technopark Centurion, Gauteng South Africa t: f: India Office No. 808-A, 8th Floor Welldone Tech Park, Sohna Road Sector 48, Gurgaon, Haryana India t: f: All information contained in this document is subject to change without prior notice Intracom S.A. Telecom Solutions