ETSI WIDEBAND CDMA STANDARD FOR THE UTRA FDD AIR INTERFACE.pdf

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ETSI WIDEBAND CDMA STANDARD FOR THE UTRA FDD AIRINTERFACE ETSI WIDEBAND CDMA STANDARD FOR THE UTRA FDD AIR INTERFACE by Nicky Jee-Ngai Yuen Electrical Engineering 563 Wireless Personal Telecommunications Systems ETSI WIDEBAND CDMA STANDARD FOR THE UTRA FDD AIR INTERFACE Submitted to Dr. P. Takis Mathiopoulos The University of British Columbia by Nicky Jee-Ngai Yuen The University of British Columbia March 30 2001 ii ABSTRACT “ETSI Wideband CDMA Standard for the UTRA FDD Air Interface” by Nicky Yuen The core requirements for the IMT-2000 air interface technology to be used in Third Generation (3G) wireless systems are: 1) up to 2 Mbps data rate for local area coverage, 2) up to 384 kbps data rate for wide area coverage, 3) highly efficient utilization of the spectrum in contrast to current 1G and 2G systems, and 4) capability to support various multimedia information sources on an ongoing basis. The radio access technology that was finally proposed in January of 1998 to meet these criteria was W-CDMA. W-CDMA is based on Direct Sequence CDMA technology, with a chip rate of 4.096 Mcps. It is designed to be flexible to accommodate third generation services as well as to be adaptable to current GSM systems. This paper presents a background to 3G systems, some key features and technologies of the W-CDMA FDD air interface, and a description of the physical channel and frame structure. iii LIST OF ILLUSTRATIONS Table 1. Key Parameters of W-CDMA 4 Table 2. Physical Channel Format .9 Figure 1. ITU Spectrum Allocation .3 Figure 2. Hierarchical Cell Structure for Smooth Handovers .6 Figure 3. Physical Channel Structure .9 Figure 4. Uplink DPDCH/DPCCH Structures 10 Figure 5. Uplink DPCH Spreading/Modulation 11 Figure 6. Random Access Scheme 12 Figure 7. Uplink PRACH Structure .12 Figure 8. Data Part of PRACH 13 Figure 9. Downlink Spreading/Modulation 14 Figure 10. Downlink DPCH .15 Figure 11. Primary and Secondary CCPCHs 16 Figure 12. Synchronization Channel 17 Figure 13. Test Route .18 Figure 14. Average BER Performance with Variable Chip Rate 20 iv LIST OF ABBREVIATIONS BCCH Broadcast Control Channel BER .Bit Error Rate BPSK . Binary Phase Shift Keying BTS .Base Transceiver Station CDMA .Code Division Multiple Access CCPCH Common Control Physical Channel DLPCH Downlink Physical Channel DPCCH .Dedicated Physical Control Channel DPCH .Dedicated Physical Channel DPDCH . Dedicated Physical Data Channel DS-CDMA Direct Sequence CDMA ETSI .European Telecommunications Standards Institute FACH Forward Access Channel FDD .Frequency Division Duplex FPLMTS .Future Public Land Mobile Telecommunications System HCS Hierarchical Cell Structure IMT-2000 International Mobile Telecommunications – 2000 ITU International Telecommunications Union MS Mobile Station OVSF .Orthogonal Variable Spreading Factor PCH Paging Channel PCH Physical Channel PN . Pseudo-Random Noise PRACH .Physical Random Access Channel PSC Primary Synchronization Code SCH .Synchronization Channel SSC .Secondary Synchronization Code TD-CDMA Time Division CDMA TDD Time Division Duplex TFI Transfer Format Indicator TPC .Transmit Power Control ULPCH Uplink Physical Channel UMTS Universal Mobile Telecommunications System UTRA UMTS Terrestrial Radio Access W-CDMA Wideband Code Division Multiple Access v TABLE OF CONTENTS ABSTRACT ii LIST OF ILLUSTRATIONS iii LIST OF ABBREVIATIONS .iv 1.0 INTRODUCTION .1 2.0 UMTS TERRESTRIAL RADIO ACCESS 3 2.1 Significant Features of W-CDMA .3 2.2 Performance Capabilities 5 2.2.1 Capacity .5 2.2.2 Coverage and Link Budget 5 2.2.3 Asynchronous BTS Operation 6 2.2.4 Handovers 6 2.2.5 Adaptive Antenna Arrays 7 2.2.6 Spreading and Scrambling Codes .7 2.2.7 Packet Access .8 3.0 PHYSICAL CHANNEL STRUCTURES 9 3.1 Physical Channel Format 9 3.2 Uplink .10 3.2.1 DPCH 10 3.2.2 CPCH 11 3.3 Downlink .13 3.3.1 DPCH 14 3.3.2 CPCH 15 4.0 EXPERIMENT ON VARIABLE SPREADING BANDWIDTH .18 5.0 CONCLUSION 21 REFERENCES .22 ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 11.0 INTRODUCTION The capability to access vast amounts of data, as well as the growing need for user mobility, has been fueled by advances in wireless personal telecommunications. The need to efficiently maximize the traffic capability of the available bandwidth and to support high-speed data for multimedia services has been the driving forces for developments in third generation, or 3G, infrastructures. Perhaps a more subtle reason for the need for 3G is the growing necessity to be able to communicate and access information “Anywhere – Anyplace”. International Mobile Telecommunications in the year 2000 (IMT-2000) is the International Telecommunications Union’s (ITU’s) vision of global wireless access in the 21st century. IMT-2000 is the new name for 3G mobile systems, which replaced the former name of “Future Public Land Mobile Telecommunications Systems” (FPLMTS). FPLMTS was targeted at developing the mobile telecommunications system including the air interface and infrastructure. The main requirements of the IMT-2000 air interface are: 1. full coverage and mobility at 144 kbps in a macrocell (i.e. in large areas such as a city); mobile (vehicular), 2. moderate coverage at 384 kbps in a microcell (i.e. a few square kilometers); portable (pedestrian), 3. limited coverage at up to 2 Mbps in a picocell; fixed, 4. high spectrum efficiency compared to existing systems, and 5. high flexibility to introduce and multiplex new services at different bit rates and Eb/N0 requirements. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 2One of the more popular technologies being developed for IMT-2000 is known as wideband CDMA. It has two versions: cdma2000 and W-CDMA. Both versions differ in chip rate, downlink channel structure, and network synchronization, but they both promise wireless voice at much higher capacity and lower cost then current 2G and 2.5G systems. The latter version, which is the focus of this paper, was proposed in January 1998 by ETSI, the European Telecommunications Standards Institute, as their proposal to the ITU for the Frequency Division Duplex (FDD) spectrum of IMT-2000. ETSI’s proposal is identified as UTRA, UMTS Terrestrial Radio Access. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 32.0 UMTS TERRESTRIAL RADIO ACCESS The ETSI UTRA is based on a wideband, 5 MHz, 4.096 Mcps Direct Sequence (DS) CDMA technology. The UTRA Network, or UTRAN, is connected to an evolved GSM core network to provide both circuit switched and packet switched services. The chip rate is extendible to higher rates of 8.192 Mcps and 16.384 Mcps. W-CDMA was selected for FDD (paired UMTS frequency band) operation, and time-division CDMA (TD/CDMA) was selected for TDD (unpaired UMTS frequency band) operation. The selection makes UTRA efficiently cover all operation scenarios and makes full utilization of the UMTS spectrum allocation. For paired bands, the spectrum will be in the 1920 – 1980 and 2110 – 2170 MHz ranges. For the unpaired band, a total of 35 MHz will be allocated. A spectrum identification has been made to identify the parts of the 2 GHz band for IMT-2000 operation. IMT-2000 MSS IMT-2000 MSS2000 2050 2100 2150 2200 22501950190018501800MSSreg.2MSS reg.2Frequency in MHz Figure 1. ITU Spectrum Allocation 2.1 Significant Features of W-CDMA The main features which make W-CDMA a promising air interface for 3G systems include: 1) improved performance over second-generation systems; improved capacity and coverage, 2) flexible service implementation and support of multiplexing parallel services on a single physical connection, ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 43) support of a wide range of services at up to 2 Mbps, 4) two packet data operation modes: dedicated and common channel packet operation, 5) fast, efficient packet access, 6) support of intra-frequency, inter-frequency, GSM-UTRA handoffs, 7) support for enhanced capabilities such as adaptive antenna arrays, multiuser detection, and interference cancellation, 8) asynchronous base transceiver station (BTS) operation, and 9) fast transmit power control (TPC) in both directions. The following table lists the key parameters of W-CDMA. Multiple-access scheme DS-CDMA Bandwidth 5 / 10 / 20 MHz Chip rate 4.096 / 8.192 / 16.384 Mcps Carrier spacing (4.096 Mcps) Flexible in the range 4.4 – 5.2 MHz (200 kHz carrier raster) Roll-off factor 0.22 Frame length 10 ms (20 ms optional) Inter-cell synchronization Asynchronous; no synchronization needed (synchronous also possible) Spreading modulation QPSK (downlink) QPSK (uplink) Data modulation QPSK (downlink) BPSK (uplink) Coherent detection User-dedicated time-multiplexed pilot (uplink and downlink), Common pilot can also be used in downlink Multirate Variable-spreading and multicode Spreading factor (ratio of chip rate over information rate) 4 – 256 (4.096 Mcps) Channel coding Convolutional coding (R = 1/3 or 1/2, K = 9), Turbo code Spreading Spreading code and Scrambling code Spreading code (downlink) Variable-length orthogonal sequences for channel separation, Gold sequences for cell and user separation Spreading code (uplink) Variable-length orthogonal sequences for channel separation, Gold sequence 241 for user separation Packet access Dual mode (common and dedicated channel) Handover Soft handover, Interfrequency handover Table 1. Key Parameters of W-CDMA [...]... through the microcell layer, at the same time offering full coverage and support of high mobility by the macrolayer [9]. Interfrequency handover is then required for a handover between different cell layers. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 20 Figure 14. Average BER Performance with Variable Chip Rate ETSI Wideband CDMA Standard for the UTRA FDD Air Interface... carries the DPCCH. The DPCCH portion of the other slots is empty. In this case, variable bit rates are achieved. The structure of the DPCH is shown in Figure 10. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 52.2 Performance Capabilities Some of the technical benefits of W -CDMA which greatly enhance its performance include the following: 2.2.1 Capacity The wide bandwidth of W -CDMA. .. ETSI WIDEBAND CDMA STANDARD FOR THE UTRA FDD AIR INTERFACE by Nicky Jee-Ngai Yuen Electrical Engineering 563 Wireless Personal Telecommunications Systems ETSI WIDEBAND CDMA STANDARD FOR THE UTRA FDD AIR INTERFACE Submitted to Dr. P. Takis Mathiopoulos The University of British Columbia by Nicky Jee-Ngai Yuen The University of... variations of scrambling codes in the system. For efficient cell search, the downlink scrambling codes are divided into 32 groups of 16 codes each. On the uplink, the scrambling code is usually a PN sequence of length 40960 chips (10 ms) as on the downlink; however, ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 215.0 CONCLUSION The framework for the next generation wireless system... rates. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 93.0 PHYSICAL CHANNEL STRUCTURES The physical channel (PCH) in a W -CDMA system encompasses all aspects of transmission over the air and is defined by the frequency and code. The physical channel can be classified into an uplink physical channel (ULPCH) and a downlink physical channel (DLPCH). Each of these can be further broken... ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 184.0 EXPERIMENT ON VARIABLE SPREADING BANDWIDTH In a paper written by Adachi, Sawahashi, and Suda [13], an experiment was conducted to analyze the effects of the spreading chip rate on the BER performance with and without diversity. The parameters of the radio link were slightly different than those normally used. The effects of these... ii ABSTRACT ETSI Wideband CDMA Standard for the UTRA FDD Air Interface” by Nicky Yuen The core requirements for the IMT-2000 air interface technology to be used in Third Generation (3G) wireless systems are: 1) up to 2 Mbps data rate for local area coverage, 2) up to 384 kbps data rate for wide area coverage, 3) highly efficient utilization of the spectrum in contrast to current... Table 2. Physical Channel Format ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 62.2.3 Asynchronous BTS Operation W -CDMA does not require tight inter-BTS synchronization as in the case of narrowband CDMA. This means that there is no requirement that each BTS should be capable of reliable GPS reception for external timing. This reduces deployment efforts significantly, especially... GSM systems. This paper presents a background to 3G systems, some key features and technologies of the W -CDMA FDD air interface, and a description of the physical channel and frame structure. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 7‘Hot-Spot’ scenarios also require the use of interfrequency handover. In a hot-spot scenario, a certain cell that serves a high traffic... shown in the experiment by Adachi, Sawahashi, and Suda, BER performance generally improves with increasing chip rate. W -CDMA is a mature technology with the capability to provide a true third-generation solution for various wireless media. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 103.2 Uplink The ULPCH can be further classified into a dedicated physical channel (DPCH) and . ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 2One of the more popular technologies being developed for IMT-2000 is known as wideband CDMA. . Radio Access. ETSI Wideband CDMA Standard for the UTRA FDD Air Interface 32.0 UMTS TERRESTRIAL RADIO ACCESS The ETSI UTRA is based on a wideband, 5 MHz,
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