多重化・多重アクセス方式の基礎 - apmc-mwe.org

1 464-8603 . Tel: +81-52-789-2743 Fax:+81-52-789-3173. E-mail: .. CDMA .. SNIR .. OFDM, MIMO . Fundamentals of Multiplexing and Multiple access Technologies Takaya YAMAZATO. EcoTopia Science Institue, nagoya University Furo-cho Chikusa-ku nagoya , 464-8603. Tel: +81-52-789-2743 Fax:+81-52-789-3173. E-mail: Abstract The paper introduces the fundamentals of multiplexing and multiple access (MA) technologies for mobile communication systems. We first provide a simple formulization of MA schemes through mathematical expression that is based on CDMA. Using the expression, three concepts of MA are introduced.

2 We also introduce two important performance measures: signal to interference-and-noise ratio (SNIR) and spectral efficiency. Based on the discussion on MA, we then introduce multiplexing techniques. We focus on OFDM, multi-code transmission, and MIMO, known as high-speed transmission schemes based on multiplexing technique. 1 .. [1] . multiple access : MA .. multiple access protocol .. Multiplexing 1: .. OFDM, .. MIMO .. 2 . frequency division multple acess: FDMA) . time division multiple access : . TDMA code division mul- . tiple accesss: CDMA space . division multiple accesss: SDMA [2, 3] .. signal.

3 To interference-plus-noise ratio; SNIR . spectral efficiency .. 1: . 2: . ak (t) k multiple access function: MA function P bk (t). c ak (t) = 1 .. BPSK .. bk (t) .. X. Frequency Division Multiple access : FDMA . bk (t) = bm,k pTb (t mTb ) (2). PDC GSM . m= .. bm,k { 1, 1} k m . Time Division Multiple access : Tb px . TDMA .. Code Division Multiple Ac- (. cess: CDMA 1, 0 t < x px (t) = (3). 0, otherwise . 1 CDMA . Space Division Multiple Ac- CDMA . cess: SDMA . CDMA.. ak (t) . Z. 1 FDMA TDMA TDMA ak (t)ak0 (6=k) (t) (4). Tb . 1 .. 2 .. k sk (t) .. sk (t) = ak (t) 2P bk (t) cos c t (1). 1. ak cos( 1 t ).)

4 B k (t) sk (t). 2. ak cos( 2 t ).. Nf ak cos( N f t ). 1. Tb 3: . 1 2 3 Nf 5: MC-CDMA . BPSK . sinc BPSK . 2fb . fc /fb N .. 4: DS-CDMA fc N= (6). fb N (spreading ratio) (pro- . cessing gain) DS-CDMA . DS-CDMA N.. DS-CDMA direct sequence code division multiple . access .. X. ak (t) = alk pTc (t lTb ) (5). TDMA. l= . alk { 1, 1} k i TDMA a1 = {N, 0, , 0}, a2 =. ak = {a1k , a2k , , aN {0, N, 0, , 0}, . k } DS-CDMA . 0 . = 0 3(b) .. CDMA.. time-synchronous CDMA . 3 (a) CDMA MC-CDMA.. a(t) . Nf X. fc = 1/Tc b(t) ak (t) = alk cos( l t) (7). fb = 1/Tb DS-CDMA l=1. s(t) 4 Nf . 2 (2fc ) . 1/Tb .. CDMA multicarrier code division multiple access : MC-CDMA 7 MC- CDMA.

5 MC-CDMA DS-CDMA . [5, 6]. 1 (1 + ). (1 + Nf ) =. Tb Tc 1 + Nf = N (1 + ) (8). DS-CDMA . 6: . = 0 MC-CDMA. DS-CDMA . n (t) n . , n (t) , n . FDMA.. FDMA TDMA MC- . CDMA 6(c) .. a1 = {Nf , 0, , 0}, a2 = {0, 0, Nf , 0, , 0}, . SDMA. = 0 . SDMA .. SDMA . h( , ; t) = p( )h( ; t) (10). , . p( ) . , , angular spread . , . 4 ak (t) = hk ( k , k ; t) .. , , 4 = 0 . , , , SDMA . , , .. 6(a) (b) A B . CDMA TDMA .. X. h( ; t) = n (t)e j2 fc n (t) ( n (t)) (9). n SNIR.. 1 . K . r(t) . r(t) = (11). K. X . ak (t k ) 2P bk (t K ) cos( c t + k ). k=1. + (t). (t) . k . i 7: . i = i = 0) . Z Tb 1. Zi = r(t)ai (t) cos c tdt (12) MC-CDMA: = 2Nf [5, 6].

6 0. DS-CDMA = 0 DS-CDMA . p MC-CDMA SNIR . Zi = P/2bm,i Tb (13) . XK Z Tb + ak (t )ai (t)dt cos k k=1(k6=i) 0. SNIR . Z Tb + (t)ai (t) cos c tdt CDMA 14 (K 1). 0. Zi = + + . CDMA . 4 14 . = 1 .. multiple access interference : MAI = 0.. 7 [7]. SNIR .. SNIR . signal to interference-and-nose ratio .. 1 . SN IR (14). (K 1) + N0 /2Eb Eb N0 .. spectral efficiency .. TDMA and FDMA: = 0.. 1 /4. DS-CDMA: = 2N [4] . 8: . 9: . [1] . K 1. = G [Erlang/m2 /Hz] (15) CDMA . Wsys AC. r = 1/3, C/N0 Ws = 8[dB] . Wsys [Hz] A[m2 ] . C G [Er- 30 40% 40% . lang/channel] CDMA FDMA TDMA . C TDMA FDMA C = 3 AC 1.. C = 7 CDMA C = 1.

7 K Quality . of Service QoS 14) FDMA TDMA . WK sys . MIMO OFDM . 9 . 1. AC C = 1/4 CDMA.. CDMA . FDMA TDMA 10 . G CDMA . voice activation 2 .. 3 . K. 15 Wsys 8 .. CDMA FDMA TDMA WKsys . Multiplexing . (C/N0 Ws ) .. (r = 1 1/3) 10 5 Frequency Division Multiplex- ing: FDM . (r = 1) CDMA .. Tb .. 10(a) Tb Tb .. 10(b) Tb .. inter-symbol interference: ISI . +1, -1 . Tb .. 10: .. Time Division Multiplexing: Tb . TDM .. Code Division Multiplexing: Tb . CDM .. Space Time Multiplexing: STM .. OFDM. multicarrier transmission . orthogonal frequency division multi- . plexing: OFDM . PHS 1/Tb orthogonal frequency division multiplexing: OFDM.

8 W-CDMA 7 a = {bm , bm+1 , , bm+Nf 1 }. multicode transmission k . space-time codes OFDM . MIMO multiple-input Nf X. multipl-output s(t) = bm+l 1 cos( l t) (16). l=1.. 11 OFDM . OFDM, MIMO OFDM . IFFT FFT .. Tb . Transmitter data FEC Interleaving IFFT. Symbol wave IQ. X a0. coder + Mapping addition shaping mod HPA. bi,0. Trasmitter block diagram of OFDM PHY bi,1. a1 sMi M. bi a2 =(si,0 ,si,1 ,si,(M-1) ). AGC. IQ Remove Demapping + FEC data S/P bi,2 Amp. X det. FFT. Deinterleaving coder PN gen. LNA aM-1 c AFC clock bi,(M-1). recovery Reciver block diagram of OFDM PHY IWHT. Receiver a0 Ts ^b 11: OFDM IEEE zi,0.

9 Decision i,0. a1 ^b zi,1. Tc ^sM. i decision i,1. ^bM. LPF a2 ^b P/S i zi,2. PN gen. decision i,2. c aM-1 ^b zi,(M-1). decision i,(M-1). WHT. 13: . 12: OFDM . OFDM . 16 OFDM Nf .. OFDM Nf . OFDM . 12 .. OFDM 14: .. DS-CDMA . W-CDMA 13 .. OFDM .. OFDM . 14 .. MIMO.. MIMO .. CDMA .. OFDM, MIMO . 15: MIMO .. [8] 15 MIMO .. N M .. MIMO t .. Ct,n , n = 1, 2, , N .. N M.. MIMO MIMO . hn,m m .. N. X. rl,m = hn,m Ct,n + t,m (17) [1] Gordon L. Stuber, Principle of Mobile Commu- n=1 nication, Kluwer Academic Publishers, 1996. t,m m . [2] CDMA . 12 ak (t).. MIMO hn,m . 7 [3] CDMA Proc. of 2001 Mi- crowave Workshops and Exhibition, MWE2001.

10 [4] T. Shibata, M. Katayama and A. Ogawa, Perfor- mance of Asynchronous Band-Limited DS/SSMA. Systems, IEICE Transaction on Communica- space-time signal processing tions, , , , Aug. 1993. MIMO . MIMO [5] . , CDMA . , , , , , 2002 3 . 4 [6] , , , , . MC- CDMA SNIR , . CDMA , , , 2002 9 . [7] Zaher Dawy and Alexander Seeger, Cover- DS-CDMA TDMA age and Capacity Enhancement of Multiservice MC-CDMA FDMA WCDMA Cellular Systems via Serial Interference SDMA Cancellation, Proc. of ICC, No. WC07-3, Jun., 2004. SNIR . SNIR [8] , Jounal of Signal Process- ing , , , 2004 5.