TD-SCDMA Standards and Technology Evolution

1、TD-SCDMA Standards and Technology EvolutionTD-SCDMA Forum ITU-R RA-2000 approved the recommendations on 3G mobile communication technology specifications including those of TD-SCDMA in May 2000. In March 2001, 3GPP fulfilled TD-SCADMA Low Chip Rate (LCR) standardization in Release 4. The improved R4

2、 and R5 specifications have newly added function points including HSDPA, air interface base station synchronization, terminal location (AOA-aided location), etc. CCSA is to promote the integration of R4 and R5, including HSDPA extension on multi-carrier. In March 2005, R6 containing uplink enhanced

3、technology (still in study) and MBMS (multimedia broadcasting/multicast) was frozen. However, proposals can still be made due to the instability of R6. In the future, TD LTE should study more the MC-TD-SCDMA and OFDM-based TDD technology.Figure 1 TD-SCDMA Evolution CCSA has developed industry standa

4、rds of technical requirements for TD-SCDMA equipments and test methods, completed research reports on IP-based RAN, multi-antenna, and HSDPA, and conducted pre-research on standards for test methods of TD-SCDMA Enhanced, TD-SCDMA P2P, TD-SCDMA HSDPA Multi-carriers, and TD-SCDMA Iur. In terms of TD-S

5、CDMA networks, 8 standards of technical requirements and test methods have been studied, of which 5 are for equipment, i.e., 2GHz TD-SCDMA wireless access equipments and terminals (Volumes I and II), and 3 for interfaces including Iub and Uu interfaces. On January 20th, 2006, the Ministry of Informa

6、tion Industry issued the TD-SCDMA Version 1, with a total of 23 recommended communication industry standards, including TD-SCDMA terminals/test specifications, wireless access equipment/test specifications, and technical specifications for wireless access interfaces. The titles and numbers of the st

7、andards are as follows: No. YD/T 1365-2006 Technical Requirements for Wireless Access Equipment of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network No. YD/T 1366-2006 Test Methods for Wireless Access Equipment of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network No. YD/T 1367-20

8、06 Technical Requirements for User Equipment of 2GHz TD-SCDMA Digital Cellular Mobile Communication NetworkNo. YD/T -2006 Test Methods for User Equipment of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part I: Tests of Basic Functions, Services and PerformanceNo. YD/T -2006 Test Metho

9、ds for User Equipment of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part II: Tests of Network CompatibilityNo. YD/T -2006 Technical Requirements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part I: General PrinciplesNo. YD/T -2006 Technical Requir

10、ements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part II: Layer 1No. YD/T -2006 Technical Requirements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part III: Signaling TransportNo. YD/T -2006 Technical Requirements for Iub In

11、terface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part IV: NBAP SignalingNo. -2006 Technical Requirements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part V: Data Transport & Transport Signaling for Common Transport Channel Data StreamsNo. -2

12、006 Technical Requirements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part VI: User Plane Protocol for Common Transport Channel Data StreamsNo. YD/T -2006 Technical Requirements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Par

13、t VII: Data Transport & Transport Signaling for DCH Data StreamsNo. -2006 Technical Requirements for Iub Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part VIII: User Plane Protocol for DCH Data StreamsNo. YD/T 1370-2006 Test Methods for Iub Interface of 2GHz TD-SCDMA Digi

14、tal Cellular Mobile Communication NetworkNo. -2006 Technical Requirements for Uu Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Physical Layer Technical Specification-1: General PrinciplesNo. -2006 Technical Requirements for Uu Interface of 2GHz TD-SCDMA Digital Cellular Mo

15、bile Communication Network Physical Layer Technical Specification-2: Physical Channels and Mapping of Transport Channels onto Physical ChannelsNo. -2006 Technical Requirements for Uu Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Physical Layer Technical Specification-3: Mu

16、ltiplex and Channel Coding No. -2006 Technical Requirements for Uu Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Physical Layer Technical Specification-4: Spread Spectrum and Modulation No. -2006 Technical Requirements for Uu Interface of 2GHz TD-SCDMA Digital Cellular Mob

17、ile Communication Network Physical Layer Technical Specification-4: Physical Layer ProceduresNo. -2006 Technical Requirements for Uu Interface of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Physical Layer Technical Specification-4: Physical Layer MeasurementsNo. -2006 Technical Requi

18、rements for Uu Interface L2 of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part 1: MACNo. -2006 Technical Requirements for Uu Interface L2 of 2GHz TD-SCDMA Digital Cellular Mobile Communication Network Part 2: RLCNo. YD/T 1373-2006 Technical Requirements for Uu Interface RRC of 2GHz

19、TD-SCDMA Digital Cellular Mobile Communication Network The following industry standards are being drafted: Technical Requirements for UICC-Terminal (Cu) Interface of 2GHz TD-SCDMA/WCDMA Digital Cellular Mobile Communication NetworkTest Methods for UICC-Terminal (Cu) Interface of 2GHz TD-SCDMA/WCDMA

20、Digital Cellular Mobile Communication NetworkThe draft project of TD-SCDMA V2 HSDPA standard was started in August 2005 and is expected to be completed by August 2006. CCSA is considering the development of test system in compliance with the TD-SCDMA standard. I. Rational for TD-SCDMA Evolution The

21、direction of WCDMA and CDMA2000 evolution appears to be evident. TD-SCDMA will soon be put into commercial use, and will inevitably develop toward higher rate transmission technology. It is an urgent task for us to research and develop the enhanced technology standards and evolution. The rapid devel

22、opment of 3G markets last year accelerated the evolution pace of WCDMA and CDMA2000. HSDPA, regarded as “E3G, was commercialized at the end of 2005. China Mobile would go to HSDPA directly if it were deploying 3G network. TD-SCDMA faces the challenge from HSDPA. The sustainability of TD-SCDMA has be

23、come an important factor for the operators (especially the new entrants) when they choose among the standards to deploy their 3G networks. In addition, some problems related to TD-SCDMA technologies have to be settled during evolution, like those concerning coverage, high-speed mobility, and interfe

24、rence among UEs and base stations. Issue of coverage: The coverage radius of TD-SCDMA system rests mainly with two factors: one is emission level and Rx sensitivity, the other is up/downlink guard time slot length. As for the emission level and Rx sensitivity of the system, compared with FDD, the re

25、quirement of TD-SCDMA for Rx sensitivity is much lower thanks to the new technologies like Smart Antenna. However, due to the duplex mode of TDD, guard time slot is required between uplinks and downlinks to guarantee non-interference between up and downlink synchronous time slots. Therefore, the cov

26、erage radius of TD-SCDMA system is restricted by the guard interval length between uplink and downlink synchronous time slots. Theoretically, the maximum coverage it supports is approximately km. Larger cell radius will cost certain system capacity. Issue of high-speed mobility: Currently ITU requir

27、es a TDD rate of 120km/h and that of FDD 500km/h, because of the continuous control of FDD system and discontinuous transmission of TDD system. Since fast fading has more effects on TDD system, TD-SCDMA faces challenges in supporting terminals of high mobility. In addition, there are several require

28、ments for TDD long-term evolution: Enhanced services: to achieve lower latency, high data-rate in real sense, like peak rate of 100Mbps for downlink and 50Mbps for uplink (the bandwidth of 20MHz), better mobility, lower costs, higher spectrum efficiency and capacity, larger coverage, and lower termi

29、nal complexity and costs;Flexible spectrum and reconfigurable bandwidth: Bandwidth can be configured based on traffic requirement, from 1.25 MHz at least to 20 MHz;Reach of all 3G environments: including wide-area coverage, such as downtown, suburban and rural areas; indoor and outdoor environment a

30、nd low and high-speed mobility environment as well; Distributed networking structure and smooth system layout; Requirements for terminals: low cost, low power consumption, and multi-antenna; The evolution path of TD-SCDMA is staged as such, namely single-carrier HSDPA/HSUPA, multi-carrier TD-SCDMA a

31、nd LTE TDD. Figure 2 TD-SCDMA Enhanced and Evolution Scenarios II TD-SCDMA HSDPA/HSUPA EnhancedThe enhanced technology of TD-SCDMA not only improves the data-rate, but lower the operation costs for each users due to better spectrum efficiency and expand network coverage and capacity. Meanwhile it gu

32、arantees the backward compatibility of the system. Undoubtedly, all these features are extremely essential that operators have to consider when looking at the performance-price ratio for 3G network deployment. 3GPP introduces two important enhanced technologies in R5 and R6 respectively, namely HSDP

33、A and HSUPA. HSDPA is applicable to both FDD and TDD system with much similarity in the way of deployment. The basic bottom-layer key technologies used include AMC (Adaptive Modulation and Encoding), HARQ (Hybrid Automatic Repeat Request), fast scheduling algorithm and etc. The theoretical peak rate

34、 can reach when the ratio of upstream and downstream time slots of TD-SCDMA single-carrier () HSDPA is 1:5. The integration of HSDPA and multi-carrier (i.e. multi-carrier HSDPA), that is to use multi-carrier technology and high-order modulation, can notably increase the peak rate and spectrum effici

35、ency of HSDPA and then further promote the capability of TD-SCDMA in its support of high-rate data services. For instance, the theoretical peak data rate of a three-carrier TD-SCDMA architecture using 16QAM is up to . Furthermore, in the multi-carrier HSDPA solution, TS0 on the complementary carrier

36、 can also be used to transmit data, and the peak rate may be further increased. A quantitative analysis indicates that three-carrier HSDPA can support a peak rate up to 10Mbps if data transmitted over TS0 on the complementary carrier. Multi-carrier HSDPA is a feasible solution to address effectively

37、 the high-capacity and high-speed transmission, while ensuring the maximum backward compatibility with the legacy TD-SCDMA network. Currently, two mature technologieshigher order modulation and more efficient scheduling algorithmbecome the most possible choices. When the environment is deemed approp

38、riate, the high-order modulation of 64QAM may be adopted. Theoretically, 64QAM can improve performance by a factor of 1.5 compared with the current 16QAM, with single-carrier peak rate reaching and three-carrier peak rate up to .Based on the simulation results, a remarkable performance gain can only

39、 be acquired when the signal to noise ratio is above 25dB if 64QAM is used in HSDPA. Therefore, 64QAM mainly works in the environment of adequate channel conditions, low-speed mobility or static status. In addition, a good scheduling algorithm may well enhance the strength inherent to the multi-carr

40、ier HSDPA technology. Currently, the most frequently used scheduling algorithms include Max C/I, polling scheduling, and proportional fair scheduling. The research of fast scheduling algorithm is going deeper and many algorithms taking into account of both maximum throughput and fairness have been p

41、ut forward, such as feedback-control scheduling algorithm derived from the improved proportional fair scheduling, rate-restricted Max C/I algorithm and etc. A good scheduling algorithm not only has to guarantee a desirable data throughput, but also takes into account the restriction of fairness. The

42、 larger the throughput is, the higher the performance ratio will be for a carrier. However, the satisfaction degree will be damaged if customers have no access to the services for a long time. A good scheduling algorithm should take into account the priority level of the services that different cust

43、omers need to transmit. Those of higher priority level should be sent earlier than others that are not so sensitive to latency. Scheduling algorithm must be integrated with HSDPA channel features so as to optimizing HSDPA performance giving a full play to the unique characteristics of HSDPA transmis

44、sion. When CCSA formulates TD-SCDMA multi-carrier HSDPA specifications, it bears in mind the goal to achieve single-user peak rate N times that of 3GPP HSDPA through carrier bundling and minimized adaptation, based on the industrial standards for 1st Edition of N frequency and 3GPP R5 HSDPA specific

45、ations, so as to better support packet services and meet the demands of operators for high-speed packet data services. The basic principle for formulating TD-SCDMA multi-carrier HSDPA specifications: compatible with the industrial standards for TD-SCDMA 1st Edition of N frequency in air interface, a

46、nd also compatible with 3GPP R5 HSDPA standards. Little alteration has been made to HSDPA in TD-SCDMA, except for a new media access control sub-layer (MAC-hs) added to Node B for high-speed data transmission control, and newly added definitions of several new transmission channels and physical chan

47、nels for forward compatibility. It is easy for TD-SCDMA network to acquire the functions of HSDPA by equipments upgrading and replacement. The reason is that many physical layer technologies of TD-SCDMA are brought to bear via software radio, so it is the strength inherent to TD-SCDMA architecture t

48、o adopt HSDPA physical layer technologies through upgrading software, rendering the hardware replacement unnecessary. As up to now we have not seen any TD-SCDMA network of large scale deployed, there is no track record regarding how to build such a network has been proved. According to the character

49、istics of TD-SCDMA, there are two possible solutions in the initial stage of network deployment, namely, cell-shared deployment between HSDPA and TD-SCDMA, and non cell-shared deployment in separate layers. Cell-sharing between HSDPA and TD-SCDMA can be done through separate carrier frequency or com

50、mon carrier frequency mode. The two systems share the resources like Node B power, carrier frequency, time slot and channelization code (CC) and give a play to their respective strengths under the unified control. The non cell-shared deployment between HSDPA and TD-SCDMA, where HSDPA alone forms a s

51、eparate layer of the network architecture. TD-SCDMA network provides CS and low-speed R4 data services, while HSDPA network mainly provides high-speed data services. The two systems will be complementary to each other in service bearing capability by a handover.Now it is a fruit-yielding time for ma

52、ny companies involved into the R&D of TD-SCDMA enhance. Datang and TD Tech are engaged in the research on HSUPA (uplink enhanced technology) based on 3GPP R6 and R7, and on MBMS (multimedia broadcasting/multicast). In October 2005, Datang Mobile launched, for the first time, TD-SCDMA HSDPA equipment

53、, with the single-carrier data rate in air interface reaching 2.8 Mbit/s, and demonstrated some typical 3G services, like VoD and high-speed FTP downloading. It is expected that Datang will be the first to make TD-SCDMA HSDPA system available for commercial use in mid 2006. Figure 3 TD-SCDMA Evoluti

54、on of Datang Mobile III TD-SCDMA LTE Solution In recent years, along with the rapid development of traditional cellular mobile communication technologies, some broadband wireless access technologies (e.g. mobile ) have taken to provide part of mobility, trying to seize a portion of mobile market sha

55、re. In this context, a new market demand arises from the mobile communication industry, which is to further improve 3G technologies to provide a stronger data service capacity, so as to serve users better and compete with other technologies. Accordingly, 3GPP and 3GPP2 initiate the research on LTELo

56、ng Term Evolution with a view of keeping the competitive edge and the dominance of 3G technologies in the market of mobile communications. 3GPP kicked off the LTE program in November 2004, and later LTE Demand Report was approved on 3GPP Conference in June 2005, where the research on StudyItem is sc

57、heduled to be complete in mid 2006 and a standard frozen in mid 2007, waiting its commercial use in 2021 as expected.All the indexes required to be met as specified by LTE program are as follow: Support the broadband of 1.25MHz-20MHz, like 1.25MHz, 1.6MHz, 5MHz, 10MHz, and 20MHz;Peak data rate: 50Mb

58、ps for uplink, 100Mbps for downlink; Support future enhanced IMS and core network; Support symmetrical and asymmetrical spectrum allocation; Packet Service is the main objective; Lower latency of wireless network: U-plan 10 ms, C-plan 100ms; Spectrum efficiency up to 2-4 times that of 3GPP Release 6

59、: 5 bps/Hz for downlink ( 3-4 times that of Release 6 HSDPA), 2.5 bps/Hz for uplink (2-3 times that of Release 6 HSUPA); Emphasizing backward compatibility, while taking into account of the system performance; Improvement of throughput at the edge of cell;Lower costs (estimated to resemble WiMAX);LT

60、E program of China is undertaken by E3G Technology Group, including ZET, Huawei, Datang and the 5th Working Group of 863 Future (including Beijing University of Post and Telecommunications (BPTU), Tsinghua University, Southeast University, RITT, and Shanghai Research Center for Wireless Communicatio