【正文】 3 bits 132 bits 4 bits 378 bits 78 bits Tail bits Parity Convolutional Code 456 bits 57 bits Even 57 bits Odd 57 bits Even 57 bits Odd 57 bits Even 57 bits Odd 57 bits Even 57 bits Odd Diagonal Interleaving 8 consecutive TDMA burst over the Um air interface Class 1b 132 bits Class 2 78 bits GSM Speech Air Interface Coding (2) GSM話音空中接口編碼 (2) Um Ne t w o r kS NDCPLLC( Not e)RLCM A CP hy s . L i nkP hy s . RFS NDCPLLCRLCM A CP hy s . L i nkP hy s . RFMSS co p e o f G S M 0 3 . 6 0S co p e o f G S M 0 3 . 6 4No t e : I n t h e n e t w o r k t h e L L C issp li t b e t w e e n B S S a n d S G S N.T h e B S S f u n ct io n a li t y is ca ll e dL L C r e la y .GPRS Data Air Interface Coding GPRS數(shù)據(jù)空中接口編碼 ? Data must be decoded in perfect condition, unlike speech 不象話音 ,數(shù)據(jù)在解碼中不允許任何錯誤 ? If errors cannot be corrected, retransmission is required 如果錯誤無法糾正 ,則必須重傳 ? RLC layer controls backward error correction over Air Interface RLC層控制空中接口的后向除錯 C o d i n g S c h e m eC o d e d b i t sP u n c t u r e db i t sD a t aR a t e( k b p s )M u l t i p l e S l o tM a x .D a t aR a t e( k b p s )C S 1 456 0 9 . 0 5 7 2 . 4C S 2 588 132 1 3 . 4 1 0 7 . 2C S 3 676 220 1 5 . 6 1 2 4 . 8C S 4 456 0 2 1 . 4 1 7 1 . 2M a x . P e r T S D a t a r a t e ( k b p s )0510152025C S1 C S2 C S3 C S4KBits per SecondGPRS Coding Schemes GPRS的編碼方案 ? GPRS using same physical RF layer as GSM speech GPRS 用與 GSM 話音同樣的物理層 ? Data is coded into normal bursts 數(shù)據(jù)也在普通脈沖 內(nèi)編碼 (456 bits / 20ms) ? Higher data rates per timeslot achieved by removing error protection 每時系的更高數(shù)據(jù) 傳輸速度是以降低 容錯性能換來的 ? GPRS has four RF coding scheme GPRS有四種無線編碼方式 ? The throughput rate in table below is for physical layer on air interface 下表中最后一列的數(shù)據(jù) , 是指空中接口物理層的最高速度 ? 右表中的最后一列數(shù)據(jù) 是指邏輯鏈路控制層的 最高數(shù)據(jù)流量 ,當(dāng) RLC 層中有可選項時速率還 會低一些 S c he m e C od eR a t eU S Fbi t sP r e c od e dU S Fbi t sR a di oB l oc k( e x c l . U S Fa nd B C S )BCS Ta i lbi t sC od e dbi t sP un c t ur e dbi t sD a t aR a t e( k bp s )C S 1 1 / 2 3 3 181 40 4 456 0 9 . 0 5C S 2 ~ 2 / 3 3 6 268 16 4 588 132 1 3 . 4C S 3 ~ 3 / 4 3 6 312 16 4 676 220 1 5 . 6C S 4 1 3 12 428 16 0 456 0 2 1 . 4S c he m e M A CH e a de r( e x . U S F)( bi t s )S pa r ebi t sR LCD a t a( oc t e c t s )R LCU s e rD a t a( oc t e c t s )U s e rD a t aTh r ou ghput( k bp s )C S 1 5 0 22 20 8 . 0C S 2 5 7 32 30 1 2 . 0C S 3 5 3 38 36 1 4 . 4C S 4 5 7 52 50 2 0 . 0GPRS Coding Schemes GPRS的編碼方案 Add BCS 加塊檢查序列 Add precoded USF 加預(yù)編碼的上行狀態(tài)標(biāo)識符 Add tail bits 加結(jié)尾碼 Coding 編碼 Puncture 穿孔減碼 456 bits Payload 有效負(fù)載 ? BCS : Block Check Sequence ? USF : Uplink State Flag GPRS Coding Procedure GPRS編碼的步驟 r a t e 1/ 2 c o nv o l uti o na l c o dingpunc t ur i ng456 bit sU S F BCSR a dio B l o c kB0 B1 B2 T B3 B4 B5 X B6 B7 B8 T B9 B10 B11 X 52 TDMA Frames 12 Radio Block Periods = 240 ms *Rectangular interleaving of one Radio Block over four bursts in consecutive TDMA frames *Interleaving CS1 CS3 Radio Block Structure CS1到 CS3的無線塊結(jié)構(gòu) CS4 Radio Block Structure CS4的無線塊結(jié)構(gòu) b lo ckco d en o co d in g4 5 6 b itsU S F B C SR a d io B lo ck*Interleaving B0 B1 B2 T B3 B4 B5 X B6 B7 B8 T B9 B10 B11 X 52 TDMA Frames 12 Radio Block Periods = 240 ms *Rectangular interleaving of one Radio Block over four bursts in consecutive TDMA frames USF T PC RLC Header RLC data BCS USF T PC RLC / MAC signaling information BCS Payload Payload MAC header RLC data block Bloc check sequence MAC header RLC / MAC control block Bloc check sequence User data Control T : Block Type indicator PC : Power Control fields GPRS Radio Block Structure GPRS無線塊結(jié)構(gòu) User data 用戶數(shù)據(jù) Segment 段 Segment 段 Info 信息 FH FCS PH Segment 段 Segment 段 Segment 段 Info BH BCS Tail Convolutional encoding 卷積編碼 Burst 脈沖 Burst 脈沖 Burst 脈沖 Burst 脈沖 ... ... Network layer SNDCP layer SNDCP layer LLC layer LLC layer RLC / MAC layer RLC / MAC layer Physical layer Packet (PDU) LLC frame 邏輯鏈路控制幀 RLC block 無線鏈路控制塊 Normal Burst 普通脈沖 PH : Packet Header 分組首標(biāo) BH : Block Header 塊首標(biāo) FCS : Frame Check Sequence FH : Frame Header 幀首標(biāo) BCS : Block Check Sequence 塊核查序列 456 bits 114 bits 114 bits 114 bits 114 bits Packet transformation data flow 分組傳輸?shù)臄?shù)據(jù)流 No Hopping f1 f1 f5 Hopping Speech amp。 distributes errors in the frame 跳頻技術(shù)通過提供多頻點交替使用 , 使衰減平均化并將錯誤離散的各幀中 ? Works in favour of convolutional coding with interleaving 跳頻最好要與卷積和交織技術(shù)共用 ? Hopping is good for speech but do not benefit data 跳頻對提高話音質(zhì)量很有好處 , 但 一般情況下對數(shù)據(jù)傳輸無益 BLER Rate TU3 No Hopping 塊錯誤率 TU3 無跳頻 Typical Urban 3 km/h No Hopping 典型城區(qū) ,移動速度每小時 3公里 ,無跳頻 1 10 100 0 4 8 12 16 20 24 C/I載干比 (dB) CS1 CS2 CS3 CS4 BLER Rate TU3 No Hopping 塊錯誤率 TU3 無跳頻 0 10 20 30 40 50 60 70 80 90 100 0 4 8 12 16 20 24 C/I載干比 (dB) CS1 CS2 CS3 CS4 ? CS4 has rapid rate of change between 6 amp。 CS2 show the least change vs. C/I CS1和 CS2受載干比的影響最小 ? CS3 amp。 CS4 best at C/I 10dB CS3和 CS4最好在載干比大于 10dB時應(yīng)用 Typical Urban 3 km/h No Hopping 典型城區(qū) ,移動速度每小時 3公里 ,無跳頻 GSM traffic model vs. GPRS traffic model GSM流量模型與 GPRS流量模型的對比 ? GSM traffic model base on user air time GSM的流量模型的基礎(chǔ)是用戶平均占用空中信道的時間 ? GPRS traffic model base on user data volume GPRS的流量模型的基礎(chǔ)是用戶平均傳輸數(shù)據(jù)的總量 ? In GSM, mobile user can not make a phone call if there is no free channel at a certain time in a cell 在