Thông tin tài liệu
FUNDAMENTALS OF MULTI-CARRIER CDMA TECHNOLOGIES 145 (l =L+1 ···J) experiences zero-gain. In addition, the signal in each channel is perturbed by an additive zero-mean complex-valued Gaussian noise, and the fading and noise processes are assumed to be mutually statistically independent, respec- tively, and also mutually statistically independent each other. The receiver, on the other hand, multiplies the received signal in each channel with an adequate weight and finally combines all the multiplier outputs. The combiner output is written as (114) r = J l=1 w ∗ l h l s +n l =w H hs +n where h, n and w are the channel gain, noise and weight vectors (J ×1), respectively, which are given by h =h 1 h 2 ···h L 0 ··· 0 T (115) n =n 1 n 2 ···n J T (116) w =w 1 w 2 ···w J T (117) The following properties are defined for h, n and s: hh H =H h (118) E hh H =H =diag 2 s1 2 s2 ··· 2 sL 0 ··· 0(119) E nn H =N = 2 n I J×J (120) E hn H =0 J×J (121) E s 2 =1(122) where H and N are called “the correlation matrix (J ×J) of the diversity channels” with non-zero eigenvalues of 2 s1 2 s2 ··· 2 sL ” and “the correlation matrix (J ×J) of the noise,” respectively, I J×J and 0 J×J denote identity and zero matrices (J ×J), respectively, and 2 n denotes the power of noise. When h is fixed, the power of the combiner output is written as E h r 2 =E h w H hs +w H nw H hs +w H n H =w H H h w+ 2 n w H w(123) where E h · denotes statistical average with h fixed. In (123), the first and second terms mean the powers of signal and noise, respectively, so the signal to noise power ratio (SNR) of the combiner output is written as (124) = S N = w H H h w 2 n w H w 146 CHAPTER 4 A solution of /w ∗ = 0 leads to a weight vector which maximizes the SNR, where · ∗ denotes complex conjugate, but here we take another approach to reach the optimum weight vector. Let us consider the following eigenvalue problem: (125) H h w =w where denotes “an eigenvalue of H h .” Defining max and w max as the maximum eigenvalue and the eigenvector associated with it, respetively, of course, they satisfy (126) H h w max = max w max Pre-multiplying (126) by w max leads to (127) max = w H max H h w max w H max w max Consequently, (124) and (127) lead to (128) max = max 2 n Eq. (128) clearly shows that, if we select the weight vector as the eigenvector corresponding to the maximum eigenvalue of H h , it maximizes the SNR of the combiner output. The rank of H h is 1 because it is defined as hh H , so the optimum weight vector is w max =h. In fact, substituting the solution into (125) leads to (129) H h w max =H h h =hh H h =h 2 w max therefore, we have (130) max =h 2 = L l=1 h l 2 Finally, the maximized SNR of the combiner output is given by max == h 2 n = L l=1 l (131) l = h l 2 2 n (132) Eqs. (131) and (132) show that, the maximum SNR of the combiner output is the sum of the SNRs of the diversity branches. The combiner with selection of w max =h is called “the Maximum Ratio Combiner (MRC).” In this case, the received waves from L +1toJ are not used for data demodulation. Therefore, we call this “a diversity system with order of L.” FUNDAMENTALS OF MULTI-CARRIER CDMA TECHNOLOGIES 147 B: Bit Error Rate Expression For binary phase shift keying (BPSK)/ coherent detection, it is well known that the bit error rate (BER) is given by (133) BER max = 1 2 erfc √ max where erfcx is the complementary error function defined as (134) erfcx = 2 √ + x e t 2 dt In the Appendix A, max in (133) has been derived with h fixed, so to calculate the average BER for the diversity system with order of L in the fading channel, we average (133) in terms of h, namely, max , because max is a function of h (135) BER div L fading =E h BER max =E max BER max where E h · and E max · denote statistical averages in terms of h and max , respec- tively. If we know the probability density function (pdf)of max as p max , then we can rewrite (135) as (136) BER div L fading = + 0 BER max p max d max The amplitude h l is complex valued-Gaussian-distributed with zero-mean, so l given by (132) is exponentially distributed. The pdf of l and the charac- teristic function defined as Laplace Transform of the pdf are respectively written as p l = 1 l e − l l (137) l = 2 sl / 2 n (138) s l = + 0 e −s l p l d l = 1/ l s +1/ l (139) where l denotes the average SNR. The characteristic function on the sum of independent variables is given by the product of the characteristic function on each variable, so it is written as (140) s max = L l=1 1/ l s +1/ l 148 CHAPTER 4 If l is different each other, by taking the inverse Laplace Transform of (140), the pdf of max becomes p max = lim → 1 2j +j −j e s max s max ds = L l=1 Ress max l = L l=1 L l =1 l =l 1 1− l / l · 1 l e − max l (141) where Resfx y denotes the residue of fx at x = y. Therefore, substituting (133), (134) and (141) into (136) results in (142) BER div L fading = L l=1 L l =1 l =l 1 1− l / l · 1 2 1− l 1+ l Furthermore, taking a Taylor series expansion up to the L-th derivative for (142) leads to (143) BER div L fading ≈ 2L −1 L L l=1 1 4 l Note that (143) is also valid when l is identical. Taking into consideration of l = 2 sl / 2 n , it is concluded that the BER is uniquely determined by the number and magnitude of eigenvalues for the channel, namely, the degree of freedom of the channel of interest. C: Equivalence Through Linear Transformation Now, assume that a receiver once linearly transforms the signals through J diversity channels and then combines all the multiplier outputs. In this case, the output of the combiner is written as r =v H Fhs +n =v H gs +v H Fn(144) g =Fh(145) where F is any unitary matrix (J ×J) representing the linear transformation as (146) FF H =I L ×L and v is a weight vector (J ×1), which is given by (147) v =v 1 v 2 ···v J T FUNDAMENTALS OF MULTI-CARRIER CDMA TECHNOLOGIES 149 Similar to the discussion in the previous section, defining G h as gg H =FhFh H , the SNR of the combiner output is written as (148) = v H G h v 2 n v H v = F H v H hh H F H v F H v H F H v therefore, selecting the weight vector as (149) v max =Fh the maximun SNR is obtained, but the value is all the same as the one before the linear transformation, because G h v max =FhFh H Fh =h 2 v max =h 2 v max (150) Consequently, any linear transformation of received signals cannot change the resultant SNR, that is (151) max = L l=1 l (151) means that the diversity system with J branches has the same BER as that with order of L. REFERENCES [1] Y.M.Rhee, CDMA Cellular Mobile Communications and Network Security, Upper Saddle River, NJ: Prentice Hall, 1998. [2] H.Holma and A.Toskala (Editors), WCDMA for UMTS, Chichester: John Wiley & Sons, Ltd., 2001. [3] S.Hara and R.Prasad, Multicarrier Techniques for 4G Mobile Communications, Norwood: Artech House, 2003. [4] N.Yee, J-P.Linnartz and G.Fettweis, “Multi-Carrier CDMA in indoor wireless radio networks,” Proc. of IEEE PIMRC’93, pp.109–113, Sept. 1993. [5] K.Fazel and L.Papke, “On the performance of convolutionally-coded CDMA/OFDM for mobile communication system,” Proc. of IEEE PIMRC’93, pp.468–472, Sept. 1993. [6] A.Chouly, A.Brajal and S.Jourdan, “Orthogonal multicarrier techniques applied to direct sequence spread spectrum CDMA systems,” Proc. of IEEE GLOBECOM’93, pp.1723–1728, Nov. 1993. [7] V.M.DaSilva and E.S.Sousa, “Performance of Orthogonal CDMA Codes for Quasi-Synchronous Communication Systems,” Proc. of IEEE ICUPC’93, pp.995–999, Oct. 1993. [8] S.Kondo and L.B.Milstein, “Performance of Multicarrier DS CDMA System,” IEEE Trans. on Commun., Vol.44, No.2, pp.238–246, Feb. 1996. [9] R.Prasad and S.Hara, “An overview of Multi-Carrier CDMA,” Proc. of the 4th IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA’96), pp.107–114, Sept. 1996. 150 CHAPTER 4 [10] S.Hara and R.Prasad, “Overview of Multicarrier CDMA,” IEEE Communications Magazine, Vol.35, No.12, pp.126–133, Dec. 1997. [11] S.Hara and R.Prasad, “Design and performanceof Multicarrier CDMA system in frequency- selective Rayleigh fading channels,” IEEE Trans. on Vehi. Technol., Vol.48, No.9, pp.1584–1595, Sept. 1999. [12] S.Haykin, Adaptive Filter Theory, 4th Ed., Upper Saddle River, NJ: Prentice Hall, 2002. [13] J.G.Proakis, Digital Communications, 3rd Ed., New York: Mc-Graw Hill, 1995. [14] M. Schwartz, W. R. Bennett and S. Stein, Communication Sytems and Techniques, Piscataway: NJ, IEEE PRESS, 1996. CHAPTER 5 CDMA2000 1X & 1X EV-DO SE HYUN OH 1 AND JONG TAE LHM 2 1 Senior Vice President, Strategy Technology Group, SK Telecom, Korea 2 Vice President Mobile Device & Access Network R&D Center, SK Telecom, Korea Abstract: In this chapter, we will discuss CDMA2000 1x and 1x EV-DO systems. We will talk about channel structure, transmission scheme, call processing, protocol layer and etc. under the topic of radio access technology. And we will talk about coverage & LBA, capacity, scheduling strategy, quality management and etc. under the topic of Engineering & Operation technology. Also, core network structure of CMDA2000 1x system will be mentioned, explanation focused on its main functional elements. Also, characteristics and advancements of next generation technology of 1x EV-DO, EV-DO Rev A and EV-DO Rev-B, will be described in this chapter. Its relation to HSDPA and WiMAX will be looked into Keywords: Mobile communication; CDMA2000 1X, Channel Structure, Transmission Scheme, Call Processing, Protocol Layers, Forward link, Reverse link, Dedicated channel, Common control channel, LAC, MAC, Engineering, Operation, Coverage, LBA, Capacity, Scheduling Strategy, QoS, LBA, Core network, IMS, EV-DO Rev A, EV-DO Rev-B, HSDPA, Mobile WiMAX 1. INTRODUCTION CDMA technology was first proposed by Qualcomm as the standard for the digital cellular services in North America. Then, the CDMA technology was authorized as an IS-95 standard of the Telecommunications Industry Association (TIA) in July 1993. IS-95A revision was published in May 1995 and is the basis for many of the commercial 2G CDMA systems around the world. In addition to voice services, IS-95A provides circuit-switched data connections at 14.4 kbps. The IS-95B revision, also termed TIA/EIA-95, combines IS-95A, ANSI-J-STD-008 and TSB-74 into a single document and offers up to 115kbps packet-switched data CDMA2000 1X is an ITU-approved as 3G standard. It can double voice capacity of IS-95A networks and delivers peak packet data speeds of 153 kbps (Release 0) or 307 kbps (Release A) in mobile environments in a single 1.25 MHz channel. To provide higher peak data rate to subscribers, 1xEV-DO technology, which part of a family cdma2000 1X digital wireless standards, stands for ”Evolution, Data-only” 151 Y. Park and F. Adachi (eds.), Enhanced Radio Access Technologies for Next Generation Mobile Communication, 151–190. © 2007 Springer. 152 CHAPTER 5 and delivers forward link data rate up to 2.4 Mbps in a single 1.25 MHz channel, addressing data only-not voice. 1xEV-DO is based on a technology initially known as “HDR” (High Data Rate), developed by Qualcomm and the standard is known as IS-856. CDMA technology shares a block of spectrum through the use of a spreading code (pseudo-random noise or PN code), which is unique to the individual use. It transmits data spread in a full available spectrum reducing the need to guard bands and increasing efficiency use. The CDMA technology accommodates users 10 to 20 times larger than those of the AMPS using FDMA. In addition, CDMA technology is the strong to high frequency selective fading characteristics due to multiple-path signals. So CDMA technology is suitable for areas with high user density or an urban area where high-rise buildings are concentrated. The Korean government adopted CDMA as the official standard for mobile digital communication through the notice of the Ministry of Communication in November 1993. SK Telecom, a Korean cellular service provider, introduced commercial cellular service based on IS-95A technology for the first time in the world in 1996. And also, SK telecom commercialized CDMA2000 1x Service in October, 2000 and 1xEV-DO Service in February, 2002. 3GPP2, the Third Gener- ation Partnership Project 2, is responsible for establishing specifications related to the synchronization-type CDMA2000, and to keep reflecting next-generation technologies (MIMO and OFDM. etc) regarding specifications to upgrade the data rate. 2. RADIO ACCESS NETWORK 2.1 CDMA2000 1x • Channel Structure – Structure and Characteristics of Forward Link Channel As shown Figure 1, channels for fast data transmission and control channels for efficient signaling control have been added to the forward link in the IS-95 standard. The forward link channels are divided into the dedicated channels and common channels. The dedicated channels are used for specific users, and include a funda- mental channel for low-speed rate transmission, a supplemental channel for fast data transmission, and a dedicated control channel for the delivery of mobile- specific control information. And also, a dedicated Auxiliary pilot channel is used with antenna beam-steering techniques to increase the coverage or data rate for a particular user. One common channel includes the pilot channel that measures channel strength and supports coherent detection and hand-off. Handoff is a procedure where a mobile phone with an on-going call changes channel and/or base station under a supervisory system. Other common channels include the sync channel that transmits data necessary for synchronization between terminal and system, and the paging channel that provides system information and paging infor- mation. There is also the broadcast control channel added to provide broadcast CDMA2000 1X & 1X EV-DO 153 Figure 1. 1x Forward link channel structure system-specific and cell-specific overhead data, and the quick paging channel that improves paging operations in slotted-mode. – Structure and Characteristics of Reverse Link Channel The below Figure 2 shows the pilot channel, the data transmission dedicated channel, and the improved access channel to be used to transmit moderate-sized data packets have been added to the reverse link in the IS-95 standard. Like the forward link channels, the reverse link channels consist of dedicated channels and common channels, both of which function similarly to dedicate and common channels in the forward link. Reverse dedicated channels include the fundamental channel, the supplemental channel, the dedicated control channel, and the power control sub-channel, which transmits the power control part Figure 2. 1x Reverse link channel structure 154 CHAPTER 5 related to reverse power control. Reverse dedicated control channels are used for the transmission of user and signaling information to the system during a call. The reverse common channels include the access channel used by a terminal for communicating to the base station for short signaling message exchanges, such as call originations, response to pages, and registrations, the common control channel used to transmit control data, an enhanced access channel that provides improved accessibility and a pilot channel that provides a phase reference for coherent demodulation and may provide a means for signal strength measurement. • Transmission Scheme and Characteristics – Transmission Channel Structure of the Forward Major improvements to the forward link in the CDMA2000 1X are fast power control that can support up to 800Hz, increased capacity through Orthogonal Transmit Diversity (OTD), enhanced battery life by quick paging channel, and dedicated channel for fast data transmission. Figure 3 shows the transmission scheme of the 9.6kbps fundamental channel. The CRC and the tail bits are added to a data bit to create a 9.6kbps bit stream. At this time, the bit stream passes through an encoder and the interleaver for power control puncturing. And then, orthogonal spreading and complex scrambling is made through the Walsh. A long PN code scrambles the channel. The rate of scrambling code depends on the code rate of input. And only PCH(Paging Channel), DCCH(Dedicated Control Channel), FCH(Fundamental Channel) and SCH(Supplemental Channel) are scrambled. A Walsh code running at the chip rate (1.2288Mcps) multiplies the data. The same code is used for both In-Phase and Quadrate components. Each channel is assigned a different Walsh code and might be of different lengths, to adjust to the spreading factor of the data required. The data is then complex PN multiplied, also at the chip rate. Figure 3. 9.6kbps FCH Transmission scheme [...]... [km] − 160 0 − 166 0 −158 3 39 8 6 74 −111 1 0 3 149 37 3 15 10 3 127 1 0 92 − 160 0 − 166 0 −158 3 39 8 6 77 −110 8 0 3 149 37 3 8 10 3 134 1 1 46 − 164 3 − 160 3 −158 1 48 9 −2 02 −109 0 0 0 157 17 3 15 10 3 134 9 1 53 − 164 3 − 160 3 −158 1 48 9 −2 26 −1 06 6 0 0 157 17 3 8 10 3 141 9 2 44 − 164 3 − 160 3 −158 1 51 9 −2 02 −1 06 0 0 0 157 17 3 15 10 3 134 9 1 53 − 164 3 − 160 3 −158 1 51 9 −2 26 −103 6 0 0 157... Parameters Data Rates (kbps) Modulation Type Bits per Encoder Packet Code Rate Encoder Packet Duration (ms) Number of Slots 9 .6 BPSK 2 56 1/4 26. 67 16 19.2 BPSK 512 1/4 26. 67 16 38.4 BPSK 1024 1/4 26. 67 16 76. 8 BPSK 2048 1/4 26. 67 16 153 .6 BPSK 40 96 1/2 26. 67 16 CDMA2000 1X & 1X EV-DO 165 Figure 15 1xEV-DO Connection procedure cover to the terminal After acquiring the traffic channel, the system sends the... the forward link Data Rates (kbps) Modulation Type Bits per Encoder Packet Code Rate Encoder Packet Duration (ms) Number of Slots 76. 8 QPSK 1024 1/5 13.33 8 38.4 QPSK 1024 1/5 26. 67 16 4 1/5 6. 67 153 .6 QPSK 1024 Physical Layer Parameters Table 2 1xEV-DO Forward Link Modulation 2 1/5 3.33 307.2 QPSK 1024 4 1/3 6. 67 307.2 QPSK 2048 1 1/3 1 .67 61 4.4 QPSK 1024 2 1/3 3.33 61 4.4 QPSK 2048 2 1/3 3.33 921 .6. .. [dBM] Receiver (Mobile) Thermal noise density [dBm/Hz] Receiver noise figure [(dB)] ∧ lor/ltc Ltc/loc −174 8 2 4 Voice Service type −174 8 2 4 43 − 16 4 26 6 2 17 41 6 Urban / Macro 1x Forward Link Morphology / Cell Model Table 4 Forward LBA −174 8 1 08 43 −9 8 33 2 2 17 48 2 1 1228800 768 00 Pedestrian 0 Data −174 8 1 08 43 −7 4 35 6 2 17 50 6 1 1228800 768 00 Vehicular 0 −174 8 1 08 43 6 8 36 2 2 17 51... 1/3 3.33 921 .6 8PSK 3072 1 1/3 1 .67 1228.8 QPSK 2048 2 1/3 3.33 1222.8 16QAM 40 96 1 1/3 1 .67 1843.2 8PSK 3072 1 1/3 1 .67 2457 .6 16QAM 40 96 164 CHAPTER 5 Figure 14 UATI Assignment flow size to transmit Main functions of the reverse link are transmission reverse data and the measured quality of the forward link, and the Ack function to support the hybrid ARQ for the forward link packet As shown Figure... sector 2 The EV-DO forward link offers a range of different data rates The data rates use each different modulation method as shown in Table 2 Modulation types used on the forward link are QPSK, 8PSK, and 16QAM QPSK modulation is used to achieve 38.4Kbps through 1.2288Mbps data rates (with the exception of 921.6kbps), and 8PSK for 82 .6 kbps and 1.8432Mbpsm and 16- QAM for 1.2288Mbps and 2.4576Mbps The code... performing a series of operations to access the system The information necessary for access to the system is received on the paging channel of Forward link After successfully accessing the system, the terminal transits into the traffic state and Power-Up Analog Mode F – pilot CH or sync CH MS Acquires System Timing Mobile Station Initialization Paging CH or BCCH, F – CCCH Mobile Station Idle State Unable... The bits per encoder packet range from 2 56 bits to 40 96 bits The basic transmission unit in the reverse link is a frame ( 26. 67ms), so it is comparably long in length compared to a forward link transmission unit (1 .67 ms slot) • Call Processing – UATI Assignment Procedure To process a call in the 1xEV-DO, the terminal must receive an address called the Unicast Access Terminal Identifier (UATI.) The UATI... a total of seven layers are used below the Point-to-Point (PPP) and each layer defines the related protocol IS-8 56 protocol stack shown in 166 CHAPTER 5 Figure 16 Authentication procedure Figure 18 is divided up 7 layers IS-8 56 stack is under TCP/IP/PPP protocol stack and supports RLP (Radio Link Protocol) – Physical Layer The Physical layer modulates, codes, and interleaves the data from the upper... The CDMA2000 1x scheduler is used for data transmission through the SCH This scheduler is launched every 260 msec, and determines related parameters such as User, SCH Start Time, SCH Duration, SCH Data Rate, and SCH Tx Power The BTS Resource Control (BRC) module requests the scheduler to allocate the SCH 1 1228800 960 0 Vehicular 1 1 1228800 960 0 Pedestrian 1 43 − 16 7 26 3 2 17 41 3 Spreading rate Chip . 9 .6 19.2 38.4 76. 8 153 .6 Modulation Type BPSK BPSK BPSK BPSK BPSK Bits per Encoder Packet 2 56 512 1024 2048 40 96 Code Rate 1/4 1/4 1/4 1/4 1/2 Encoder Packet Duration (ms) 26. 67 26. 67 26. 67 26. 67. 1/3 1/3 1/3 Encoder Packet Duration (ms) 26. 67 13.33 6. 67 3.33 6. 67 1 .67 3.33 3.33 1 .67 3.33 1 .67 1 .67 Number of Slots 16 84241221 2 1 1 164 CHAPTER 5 Figure 14. UATI Assignment flow size to. Data-only” 151 Y. Park and F. Adachi (eds.), Enhanced Radio Access Technologies for Next Generation Mobile Communication, 151–190. © 2007 Springer. 152 CHAPTER 5 and delivers forward link data rate up to 2.4
Ngày đăng: 07/08/2014, 21:20
Xem thêm: Enhanced Radio Access Technologies for Next Generation Mobile Communication phần 6 potx, Enhanced Radio Access Technologies for Next Generation Mobile Communication phần 6 potx
