eNB :
- Physical Downlink Shared Channel (PDSCH) ; DL SCH PCH ( 4-, 16- 64-)
Physical Downlink Control Channel (PDCCH) , UE PCH, DL-SCH,UL-SCH Hybrid ARQ, DL-SCH. PDCCH eNB , UE, . , 4-.
Physical Hybrid ARQ Indicator Channel (PHICH) ; Hybrid ARQ ACK/NACK ( 4-).
Physical Broadcast Channel (PBCH) ( 4-).
Physical Multicast Channel (PMCH) ( 4-, 16- 64-).
Physical Control Format Indicator Channel (PCFICH) , PDCCH ( 4-).
, . 3.15.
. 3.15. , LTE.
, eNB 2 : PSS (Primary Synchronization Signal) SSS (Secondary Synchronization Signal), . SSS PSS 0 5 OFDM- 0 10 . 0 . 3.16. SSS PSS 6 . PBCH 0 6 4- OFDM- 1. PBCH 4- .
PCFICH, PDCCH PHICH . / HSPA UMTS. PCFICH CFI (Control Format Indicator), .. OFDM-, PDCCH. 1 4 OFDM- . OFDM- .
: (PDCCH) 3 OFDM-, . 3.17.
PDSCH , , eNB UE SIB (System Information Blocks). . PDCCH ; DCI (Downlink Control Information) .
|
|
. 3.16. 0
[16]:
- C-RNTI <16 > ,
- RA-RNTI (Random Access) <16 > ,
- P-RNTI = <FFFE> (),
- SI-RNTI = <FFFF> (System Information) .
.3.17.
() [17]. LTE , . (). . (.3.9). . , , , , .
3.9
( ) | ( ) |
≤10 | |
11 ‒ 26 | |
27 ‒ 63 | |
64 ‒ 110 |
DCI - MCS (Modulation and Coding Scheme)[4], UE, HARQ. LTE 29 MCS 4-, 16-, 64- [17]. MCS UE . , () .
PDSCH . 3.18.
. 3.18.
1. UE PUCCH PUSCH eNB CQI (Channel Quality Indication), eNB [5].
2. (scheduler) eNB . UE PCFICH PDCCH, .
3. eNB PDSCH.
4 UE (ACK/NACK) .
MIMO
MIMO (Multiple Input Multiple Output) - , :
- / () (beamforming),
- [12].
|
|
MIMO . MIMO : M , N . . 2.19.
, (.2.19),
r = H × s + n (2.5)
r s - , n .
.2.19. N
H:
(2.6)
hij i j . , , , .
( ), UE , eNB 10λ ( ). λ, . , , , UE. . eNB, , , . . , hij..
hij , (). (. 2.13). .
/ (- ), (- ) [14]. - (Space Time Coding STC). 2×1 (.3.20) 1 2 S1 S2 - S* 2 :
1 | 2 | |
t = 0 | s1 | s2 |
t = 1 | -s2* | s1* |
. 2.20. STC 2×1
t = 0 t = 1 :
r(0) = h1s1 + h2s2 + n(0) (2.7)
r(1) = -h1s2* + h2s1* + n(1),
n(0) n(1) ().
s1 s2 :
y1 = h1*r(0) + h2r*(1) = (|h1|2 + |h2|2)s1 + h1*n(0) + h2n*(1) (2.8)
y2 = h2*r(0) - h1r*(1) = (|h1|2 + |h2|2)s2 + h2*n(0) h1n*(1)
, /
(2.9)
(2.9) , (h1 h2 →0), .
. , .
LTE MIMO (SU-MIMO), MIMO (MU-MIMO). SU-MIMO , , UE. UE .
|
|
MU-MIMO UE, . MU-MIMO UE. . 2.21 MU-MIMO 4 UE.
.2.21. MU-MIMO 4 UE
Rel.8 Rel.10 MIMO (.2.3).
2.3.
LTE | LTE-A | |||
8 | 9 | 10 | ||
SU-MIMO | 4 | 4 | 8 | |
MU-MIMO | 2 | 4 | 8 | |
SU-MIMO | 1 | 1 | 4 | |
MU-MIMO | 8 | 8 | 8 |
MIMO LTE-A. eNB , UE, , (2.6). , 4- 15% (.2.1). 8 , LTE-A .
-, (CRS), 4 (.2.13). , .2.13 CRS . , () 05 . CRS . (n) = 1(n) + j2(n), 4 : 1+j, 1j, -1+j, -1-j, 4 4-. 1(n) 2(n) , -, , eNB .
LTE-A eNB, CRS, : CSI-RS (Channel State Information Reference Signal) UE-RS (UE specific Reference Signal).
. . , /. , N . , [6], .2.19 N M. , (, N=4 =2 N=2 =2) . , .
[12], [17].
. . s. s , :
(2.10)
16- 216 , 4 ‒ 416, 64- 464 . , , , .
|
|
.
, (2.4). ZF (Zero-Forcing). , - N, s , (2.5) H-1 :
s = H-1 × r H-1 × n (2.11)
N , N× (NM). MP -, , - . , hij - .
(2.12)
×N. (2.11) H-1 MP,
s = MP × r MP × n (2.13)
ZF- (2.11) (2.13) , , MP × n .
ZF-, MMSE (Minimum Mean Square Error). MMSE- MP WMMSE:
(2.14)
- /, M.
.
, , ό . Vertical-Bell Labs Layered Space Time Architecture V-BLAST. V-BLAST , . QR- HNM . HNM
NM = QNM RMM (2.15)
QNM , :
,
RMM
(2.16)
(2.5), ,
, (2.17)
, . , .
(2.18)
, s, sM. V-BLAST [1, .15].
V-BLAST / (SNR) .2.22. 2 16- 2 .
. 2.22.