WCDMA Frequency Refarming: A leap towards ubiquitous mobile broadband coverage

Transcription

1 Nokia Networks WCDMA Frequency Refarming: A leap towards ubiquitous mobile broadband coverage Nokia Networks white paper WCDMA Frequency Refarming

2 Contents Executive summary 3 Why WCDMA in the 900 MHz band? 4 Mastering the technical challenges of WCDMA frequency refarming Nokia Networks frequency refarming solution 13 Abbreviations 15 8 Page 2

3 Executive summary Spectrum is arguably the scarcest and most valuable of all the resources needed for mobile communications. To meet the demand created by smart devices, machine-to-machine (M2M) communications and the ongoing boom in mobile broadband everywhere, most operators will need to place a high priority on making the most effective use of their finite spectrum holdings. One increasingly popular way to deliver broadband services over sparsely populated areas and indoors is through refarming GSM 900/1800, GSM 850/1900 and CDMA in 850/1900 MHz frequency bands to WCDMA. Better performance indoors and outdoors Operators wishing to introduce WCDMA to their GSM, CDMA, or TDMA bands can now refarm part or all of their frequencies and roll out 3G at remarkably low cost. Lower frequencies transmit over greater distances and penetrate better indoors. This means fewer sites covering greater areas, saving considerable rollout and operating costs as operators seek to bring bona fide broadband to rural areas and improved data rates to metropolitan indoor locations. Maximizing returns on legacy assets and resources Many markets have already successfully refarmed 900 MHz for UMTS; others are poised to follow suit. Nokia Networks is the world s most experienced vendor in WCDMA network refarming, with 76 WCDMA refarming customers, including three customers refarming with Dual Cell. Working with several operators, Nokia Networks launched the industry s first refarmed WCDMA networks as long ago as 2007 and the world s first commercial refarmed Dual Cell 900 network in Nokia Networks has developed a cost- and energy-efficient solution that enables operators to adapt and adopt at their own pace. Leveraging unique hardware and software features, this solution helps operators migrate their networks to WCDMA, smoothly and seamlessly. To this end, the company re-uses legacy assets and resources better than any other vendor s offering. All this, as well as Nokia Networks end-toend offering of radio access equipment, functionalities, management systems and professional services, make the transition simple and the overall solution far less complex. At the same time, Nokia Networks products allow for hardware re-use if, as a next step, a frequency band is refarmed to LTE. For reasons of simplicity and clarity, the rest of this paper discusses 900 MHz refarming. All the statements apply equally to 850 MHz refarming. Page 3

4 Why WCDMA in the 900 MHz band? Operators have many compelling reasons to deploy WCDMA in the 900 MHz band. Once the obstacle of regulations had been removed, refarming of UMTS 900 soon followed, and to date UMTS 850 and 900 have been deployed in around 60 countries around the world. Drivers are the promise of ubiquitous mobile broadband and the decrease in the amount of GSM traffic. The 900 MHz band will see an increasing amount of LTE refarming in the future. However, in many countries, the penetration of 3G devices will be higher than LTE, and from the lower bands typically 800 MHz is the first band on which LTE is being deployed. Adding the ability to re-use hardware in a later phase with LTE, as will be explained in another section of this paper, it makes sense to refarm to 3G first in the 900 MHz band and only then transition to LTE. The physical advantage The physics of radio wave propagation help to explain one of the great advantages of WCDMA 900 the lower the carrier frequency, the further radio signals can travel. This means it takes fewer radio cells to cover the same area, making WCDMA 900 the perfect solution for extending mobile network coverage (see Figure 1). What s more, a radio signal traveling through the walls of a building at a lower carrier frequency is less susceptible to penetration loss. With the benefit of this property, WCDMA 900 can extend indoor coverage and improve Quality of Experience in metro areas. Perhaps most important to operators, it can do all this at remarkably low cost and with compelling efficiency. Measurements and experiences with a multitude of commercial WCDMA 900 networks have demonstrated these advantages in practice. How to maintain GSM customers? One of the essential demands of operators is to ensure that services to existing GSM customers are maintained during and after refarming. This means that the existing GSM traffic needs to be squeezed into a smaller spectrum while maintaining the existing capacity and network WCDMA 900 WCDMA 2100 Scenario 1: Rural 3G coverage extension Scenario 2: Urban 3G coverage improvement Scenario 3: Initial 3G rollout Figure 1: Coverage-driven application scenarios for WCDMA 900 Page 4

5 quality. Based on Nokia Networks experience with 76 WCDMA refarming customers, this requirement can be met successfully with the company s advanced GSM and WCDMA software solutions. These solutions are explained in detail later. WCDMA 900 vs. WCDMA 2100 Operators can deliver high-revenue services profitably by running HSPA in the 900 MHz band. Savings come built-in, as WCDMA 900 requires 65% fewer sites than WCDMA in the 2100 MHz band. The total cost of ownership (TCO) for WCDMA in a rural environment is lower at 900 MHz as much as 60% lower factored over five years. Better radio propagation properties at 900 MHz translate to better services, delivered faster to more users. Even inside buildings, users in a typical suburban environment can enjoy mobile broadband service when HSPA 900 is deployed at GSM 900 base station sites. See also Figure 1 and Figure 2 for the coverage benefits provided by WCDMA 900. WCDMA Mbps WCDMA 2100 Voice GSM 1800 Voice GSM 900 Voice WCDMA Mbps 2 Mbps data service on GSM voice grid WCDMA 900 Voice Cell area [km 2 ] Figure 2: A comparison of GSM and WCDMA coverage at different frequencies. Shows a cell area in a typical suburban environment with service (voice and 2 Mbps data using Dual Cell) available inside a building. WCDMA 900 provides on average 2 Mbps coverage using the GSM site grid. Fast facts Why should we use WCDMA in the 900 MHz band? The simple answer is because it offers: Cells that are 2.8 times larger and therefore enable easier rollout and better coverage TCO reduced to 60% compared with 2100 MHz networks Cost-efficient 3G coverage of large areas, with 65% fewer sites compared with WCDMA in the 2100 MHz band Improved data rates and coverage indoors Page 5

6 Average HSPA data rate kbps HSPA 900 HSPA % Outdoor Indoor, -10 db penetration loss +130% Indoor, -20 db penetration loss Figure 3: Indoor penetration of HSPA at 2100 MHz and 900 MHz. The higher the penetration loss caused by the building s walls, the greater HSPA 900 s performance gains compared with HSPA (This refers to HSPA single carrier data rates.) The evolutionary path of WCDMA 900 Like WCDMA 2100, WCDMA 900 is evolving to higher data speeds and increased efficiency. 3GPP (3rd Generation Partnership Project) Release 8 has brought downlink data rates up to 43 Mbps and uplink data rates up to 11 Mbps, which can be seen in the field today. Further 3GPP releases, as shown in Figure 4, bring many more improvements, like up to eight carriers in the downlink and four in the uplink, 4x4 MIMO in the downlink as well as uplink MIMO and uplink beamforming. 3GPP R7 12/2007 3GPP R8 03/2009 3GPP R9 03/2010 3GPP R10 06/2011 3GPP R11 12/2012 3GPP R12 06/ QAM HSDPA 2x2 MIMO 16QAM HSUPA CPC L2 optimization High speed FACH Flat architecture Dual Cell HSDPA CS voice over HSPA High speed RACH Fast HSDPA cell change LTE interworking DC-HSDPA + MIMO Dual cell HSUPA Dual-band HSDPA Transmit diversity for non-mimo terminals 4-carrier HSDPA Minimization of drive testing Automatic neighbor lists Inter-frequency detected set HSDPA Multiflow 8-carrier HSDPA 4x4 MIMO Uplink beamforming Uplink MIMO 64QAM HSUPA Further enhanced FACH Content under study HetNet Enhanced HSUPA Enhanced DCH for CS voice Scalable BW UMTS Wi-Fi interworking HSPA+ Long Term HSPA Evolution x Mbps Downlink peak rate / DL peak rate feature x Mbps Uplink peak rate / UL peak rate feature 28 Mbps 11 Mbps 42 Mbps 11 Mbps 84 Mbps 23 Mbps 168 Mbps 23 Mbps 336 Mbps 35 Mbps 336 Mbps 35 Mbps No peak rate increases in Release 12 Figure 4: Main features of HSPA releases, specified in 3GPP Page 6

7 North America 700, 850* and 1900 MHz 1.7/2.1 GHz EMEA 2100 MHz 850*, 900* and 1800 MHz 2.6 GHz APAC 2100 MHz 850*, 900*, 1800 and 1900 MHz Latin America 2100 MHz 850*, 900*, 1800 and 1900 MHz 1.7/2.1 GHz Operating 3GPP Operating Band Total Uplink Downlink band Release band name spectrum [MHz] [MHz] Band I Rel. Band 99 I 2100 MHz 2x60 MHz Band II Rel. Band 5 II 1900 MHz 2x60 MHz Band III Rel. Band 5 III 1800 MHz 2x75 MHz Band V Rel. Band 6 V 850 MHz 2x25 MHz Band VIII Rel. Band 7 VIII 900 MHz 2x35 MHz Main 3GPP bands for refarming * Near-term WCDMA refarming potential Figure 5: The main WCDMA frequency bands and near-term refarming potential To improve performance for users at the cell edge, Release 11 introduces Multiflow. Currently 3GPP is focusing on Release 12, where the focus is not on peak data rates, but rather on making the system more efficient. For more information on these improvements, see the white paper Taking HSPA to the next level with Release 12 and beyond. Page 7

8 Mastering the technical challenges of WCDMA frequency refarming Operators seeking to capitalize on the potential of WCDMA 900 refarming must protect legacy business interests, sustain current operations and find a way to contain rollout costs. In other words, operators aiming to refarm frequencies must resolve three major issues: Minimize the impact of WCDMA frequency allocation on their GSM business Sustain business with users who have GSM-only phones Cut operational expenditures associated with the added WCDMA 900 radio access layer Making the most of narrowly defined spectrum The 900 MHz band, denoted as Band Class VIII, is defined as the paired bands from 880 to 915 MHz in the uplink direction, and from 925 to 960 MHz in the downlink. This means the overall bandwidth potential comes down to just two times 35 MHz, compared with two times 60 MHz in the UMTS core band (Band I) at 2100 MHz. Operators are compelled to share this spectrum. What is more, it must also support continued GSM/EDGE operation, as M2M contracts and GSM-only phone traffic need to be served, although overall GSM traffic decreases. A clear action plan Operators looking to extend their 3G network s reach by means of WCDMA 900 need a clear action plan that helps them rise to the three key challenges of refarming. As the supplier of the world s first commercial WCDMA 900 network and current market leader in WCDMA 900 refarming, Nokia Networks has a proven end-to-end solution engineered specifically to tackle these challenges. This solution combines unique radio access equipment and features supported by OSS and professional services to introduce WCDMA 900 smoothly. to tackle three big challenges Let s have a closer look at these three challenges and Nokia Networks approach to tackling each of them. Page 8

9 1. Minimize the impact of WCDMA frequency allocation on GSM business 3GPP calls for a carrier spacing of 5.4 MHz between WCDMA and GSM carriers. 3GPP s assumption is based on the performance of typical radio frequency (RF) filters in base stations and on a worst case power level scenario in adjacent carriers. 3GPP s recommended carrier spacing poses a challenge for a 2G/3G operator wishing to introduce WCDMA 900. The answer is, of course, to save bandwidth by condensing carrier spacing. Our Configurable Carrier Bandwidth technology allows operators to use software to configure WCDMA bandwidth in 3.8 MHz or 4.2 MHz. When refarming to WCDMA, this flexibility allows operators to keep more spectrum in GSM to maintain service to GSM customers. In fact, the 3.8 MHz WCDMA bandwidth allows many operators with restricted GSM frequency allocation to start providing WCDMA services while continuing to deliver GSM services. Configurable carrier bandwidth allows operators to deploy Dual Cell HSPA+ refarming services in 7.6 MHz (2 x 3.8 MHz) of bandwidth, which is substantially less than the 10 MHz conventionally needed by networks for two-carrier solutions. Such industry-leading spectral efficiency allows many operators to offer Dual Cell HSPA+ for the first time while still continuing to provide GSM services. In addition, coverage-based handovers enable continuous service provisioning, ensuring potential discontinuities in cell coverage go unnoticed by subscribers. With Nokia Networks service- and loadbased intersystem handovers, the operator can strike an optimum balance of the system load between GSM and WCDMA networks. Page 9

10 2. Sustain business with users who have GSM-only phones, serve M2M traffic Using GSM spectrum more efficiently is another way of mitigating the impact of WCDMA 900 refarming on GSM operations and making the most of the remaining GSM carriers capacity. Frequency hopping techniques, dynamic power control and discontinuous transmission are three well-known methods of boosting GSM spectral efficiency. Other advanced methods to further increase GSM spectral efficiency include: Orthogonal Sub Channel (OSC) can provide up to double the number of radio channels for circuit switched voice traffic. With OSC, fewer GSM hardware radio timeslot resources are needed for voice and data services. This also helps to reduce data services congestion as the average data throughput can be up to 30% higher, based on live network measurements. Smart Resource Adaptation (SRA) allocates downlink radio timeslot resources as needed. In conventional networks, radio resources are allocated by mobile device multi-slot class. Today, however, most transferred packets are small, meaning that multi-slot allocation is inefficient, as one user may reserve five resources. With SRA, shallow packet inspection (SPI) is used to allocate only one timeslot for small packets, allowing for up to five times more users, or fewer radio resources to be used. Precise paging a network will page all cells to alert the base station for incoming voice, data calls and text messages. Conventionally, common control signaling channels are added if there are enough frequencies. However, the Precise Paging feature will page only the cell where the base station was last known, as well as adjacent cells. As well as increasing paging capacity by up to 70% in both Air and Abis interfaces, paging success is raised for a better perceived quality for the subscriber. Page 10

11 Dynamic Frequency and Channel Allocation doubles base station site traffic capacity using a powerful base station controller (BSC) algorithm that optimizes the call quality in radio channel allocation for every new call and incoming handover. Dynamic allocation allows a more comprehensive re-use of GSM channels, helping operators to add more hardware capacity per MHz. This enables GSM implementation in less spectrum, or more traffic to run within the existing spectrum. Flexible MCPA transmission power pooling conventionally, Multi Carrier Power Amplifier (MCPA) power is shared equally between carriers. This GSM Software Suite feature allows output power to be shared dynamically between GSM carriers. This cuts the RF power needed for GSM, reducing energy consumption and providing more power for 3G HSPA/LTE. Energy Efficient Coverage (EEC) similar in operation to Multiple Input Multiple Output (MIMO) in LTE networks, EEC can up to double the amount of traffic carried at the cell level using existing GSM spectrum. It can also achieve the same GSM performance using less spectrum, thus freeing up more spectrum and transmitter power for frequency refarming. In addition, the feature can improve coverage by typically 4 db. Smart Dual Beam (SDB) intelligently builds 3-sector GSM sites to enable operators to benefit either from 50% more GSM capacity in their existing spectrum and base station sites, or by refarming 20% spectrum for HSPA/LTE deployments. Page 11

12 3. Cut operational expenditure associated with the added WCDMA 900 radio access layer Introducing another radio access layer adds to the operational effort. This extra effort may be minimized by making intelligent use of synergies at all levels. Site overhead, mainly driven by site rental, energy and transmission costs, is another major expense. Compact, energy-saving WCDMA 900 base stations that can use legacy site hardware such as antennas and accessories can augment existing GSM sites without significantly adding to the costs. A common backhaul architecture and infrastructure for GSM and WCDMA can reduce transmission costs. Nokia Networks multicontroller platform allows for step-by-step refarming with the possibility of re-using hardware module between GSM/EDGE and WCDMA controllers. Multicontroller platform Evolution from BSC to RNC RNC mode modules Upward trend of WCDMA capacity requirements Hardware module re-use for higher WCDMA capacity RNC mode modules BSC mode modules Downward trend of GSM/EDGE capacity requirements BSC mode modules Module re-use between GSM/EDGE and WCDMA Figure 6: Ultimate hardware module re-use between GSM/EDGE and WCDMA controllers Planning a network and setting parameters are big cost factors at the start of a project. Later, assurance and optimization processes become part of the operating equation and drive network management costs accordingly. An integrated planning and operations solution, automated and proven many times over, speeds up the initial phase, prevents errors and slashes start-up costs. A common Operations Support System (OSS) solution for GSM and WCDMA in all bands reduces operational costs because shared procedures translate to less training effort, better resource utilization, fewer errors and greater efficiency. Page 12

13 Nokia Networks frequency refarming solution Nokia Networks sees WCDMA 900 as the perfect platform for bringing the mobile broadband experience to users in rural areas. The lower frequency offers the fringe benefit of closing suburban and urban mobile broadband coverage gaps, especially within buildings. This is a side-effect that both operators and metro users alike will value. Because the company believes so strongly in the merits of frequency refarming, it has developed network planning services and powerful tools for analyzing traffic and legacy networks design as well as the multicontroller platform for stepwise refarming. Armed with these insights, Nokia Networks engineers tailor the best refarming solution for a given scenario, selecting the appropriate WCDMA spectrum allocation and spectral efficiency features to satisfy the operator s needs. This solution approach allows the WCDMA bandwidth to be reduced from 5.4 MHz to 3.8 MHz and serves to increase GSM spectral efficiency. Compact, modular, and engineered to consume less power, the Flexi Base Station enables effective site acquisition and re-use. Flexi Multiradio 10 Base Station is the latest generation of the marketleading Flexi Multiradio Base Station family. It is based on a new third generation system module platform developed to support higher GSM, HSPA+, LTE and LTE-A capacities and a wider variety of base station site configurations with a minimum of equipment and lower power consumption. This ensures that the next step in refarming to LTE can be performed using the same hardware. Flexi Multiradio 10 Base Station is the world s smallest softwaredefined, multi-technology, high-capacity base station. No additional cabinet or shelter is needed as the base station is perfectly suited for indoor as well as outdoor use. Thanks to its modular design, operators can start with small configurations and scale up as markets grow. Expansions are easy, starting with remote software upgrades, adding capacity sub-modules and chaining additional modules. A compact structure combined with a high level of integration also makes Flexi Multiradio 10 Base Station a benchmark in energy consumption, creating additional cost savings. Nokia Networks was the first company to provide radio frequency sharing, offering this facility since 2008 with Flexi Multiradio Base Station. Thanks to radio frequency sharing with a simple software upgrade, the existing base station RF can be used simultaneously for both GSM and LTE, or GSM and HSPA, depending on the frequency band. Nokia Networks RF sharing has opened the door to refarming for many operators, as it is a cost-efficient configuration one less RF module is needed, while it also offers fast rollout and re-use of assets. Page 13

14 The refarming to HSPA solution builds on one-pipe backhaul architecture, enabling operators to scale transport capacity to suit HSPA services bandwidth demand and migrate traffic smoothly from GSM to HSPA. The common NetAct OSS for 2G and 3G automates planning and parameter optimization and harmonizes operational procedures. The common OSS approach for GSM and WCDMA 900 and 2100 facilitates northbound integration. Committed to WCDMA frequency refarming Confident in the validity of WCDMA frequency re-allocation, Nokia Networks has made a strong commitment to refarming. Many operators have already refarmed part of their 900 MHz spectrum to WCDMA. According to GSA, 80 operators have commercially launched WCDMA 900 MHz in 57 countries. Close to 50% of those are supported by Nokia Networks. GSM & WCDMA functionalities OSS tools & functionalities Base station site system Services Figure 7: The Nokia Networks WCDMA refarming solution leverages comprehensive 2G/3G optimization to ensure highly efficient WCDMA and GSM operation in the 900 MHz band Strong arguments for a strong solution With its WCDMA frequency refarming solution, Nokia Networks aims to help operators to provide 3G coverage efficiently by deploying WCDMA in the 900 MHz band and sharing bandwidth with GSM. This end-toend solution for smooth WCDMA frequency refarming ensures GSM capacity and service quality remain unchanged, enabling 3G and GSM to co-exist. Best of all, operators can make the most of legacy assets and resources while capitalizing on promising new broadband business opportunities. Page 14

15 Abbreviations 3GPP BSC CDMA EDGE EEC GSA GSM HSPA LTE M2M MCPA MIMO OSC OSS RF RNC SDB SPI SRA TCO TDMA UMTS WCDMA Third Generation Partnership Project Base Station Controller Code Division Multiple Access Enhanced Data Rates for GSM Evolution Energy Efficient Coverage Global mobile Suppliers Association Global System for Mobile Communications High Speed Packet Access Long Term Evolution Machine-to-machine Multi Carrier Power Amplifier Multiple-Input Multiple-Output Orthogonal Sub Channel Operational Support System Radio Frequency Radio Network Controller Smart Dual Beam Shallow Packet Inspection Smart Resource Adaptation Total Cost of Ownership Time Division Multiple Access Universal Mobile Telecommunications System Wideband Code Division Multiple Access Page 15

16 Public Nokia is a registered trademark of Nokia Corporation. Other product and company names mentioned herein may be trademarks or trade names of their respective owners. Nokia Nokia Solutions and Networks Oy P.O. Box 1 FI Finland Visiting address: Karaportti 3, ESPOO, Finland Switchboard Product code C WP EN Nokia Solutions and Networks 2014