1、EDGE基本原理简介,目录,EDGE简介 EDGE与GPRS的关系 EDGE无线调制介绍 EDGE关键技术 EDGE性能,EDGE简介,WHAT is EDGE,Enhanced Data rates for GSM Evolution This meansA bigger pipe for stuff to go across the 2G Network!In the begging it was been like trying to shift an elephant in terms of utilisation off across the mature networks,EDGE
2、 brings 3G to GSM standard,Ave. 4,4 times higher GPRS capacity and data user rates Ave. 150-200 kbps GPRS data rates (C/I=18dB, 4TSL MS)Max. 473 GPRS kbps data rate per user Up to 5,7 times higher capacity and datarates compared to GPRS Later on above 2Mbps (rel 5/6)EGPRS and voice call simultaneous
3、ly Dual Transfer Mode,EDGE Improvement Areas,Three advanced techniques in the radio link that allow EDGE to achieve extremely high spectral efficiency for narrowband ( 100 Kbps) cellular-data services.Octonary Phase Shift Keying (8-PSK): allows the radio signal to transmit three bits of information
4、in each radio simbolMultiple coding schemes: the network can adjust the number of bits dedicated to error control based on the radio environment.Incremental redundancy: if blocks of data are received in error, EDGE sends an incremental amount of error-correcting data in each retransmission more like
5、ly to succeed than the prior one.,EDGE与GPRS的关系,EGDE Impact of on existing GSM/GPRS networks-1,EDGE is an add on to GPRS network (new modulation technique and channel data coding) and cannot work alone. GPRS and EGPRS have different protocols and different behavior on the base station system wide.,EG
6、DE Impact of on existing GSM/GPRS networks-2,Software upgrades in the base station system enable use of the new protocol. The protocols that are influenced by the introduction of EDGE are the one closest to the physical layer (radio link control and mobile allocation channel). New transceiver units
7、in the base station enable use of the new modulation technique,EGDE Impact of on existing GSM/GPRS networks-3,The are also impact on Mobility Management: EGPRS multislot class 8PSK power classAnd Radio Resource Management: support for setting up and maintaining EGPRS temporary block flows(8PSK,IR) s
8、ignaling supporting the RLC link quality control and measurement procedures,EGDE Impact of on existing GSM/GPRS networks-4,There are also some minor modification to the base station system GPRS protocol. All the rest of the protocol stack remain the same. Physical Layer:New modulation and coding sch
9、emes & Incremental Redundancy RLC/MAC Link adaptation: Quality reports, re-segmentation, new header information elements Increased RLC window size New ACK/NAK mechanism,EGDE Protocol Stack,EDGE协议层,Major Changes,物理层： 调制 增量冗余-ARQII 编码(CS)RLC/MAC层： 每帧的块数 ACK/NACK窗口大小 64-1024 码族 新的测量报告 链路适配算法,EDGE调制技术,G
10、PRS vs.EDGE,GPRS与EDGE编码速率,Both GPRS CS1 to CS4 and EGPRS MCS1 to MCS4 use GMSK modulation with slightly different throughput performances. This is due to differences in the header size (and payload size) of the EGPRS packets. This makes it possible to resegment EGPRS packets. A packet sent with a hi
11、gher coding scheme (less error correction) that is not properly received, can be retransmitted with a lower coding scheme (more error correction) if the new radio environment requires it. This resegmenting (retransmitting with another coding scheme) requires changes in the payload sizes of the radio
12、 blocks, which is why EGPRS and GPRS do not have the same performance for the GMSKmodulated coding schemes. Resegmentation is not possible with GPRS.,EDGE range is LIMITED with a normal GSM 0505 spec PA,EDGE BTS requires 3-4 dB more Tx power headroom,Motorola CTU II provides this additional power Ca
13、pability EDGE = GMSK + 8PSK,EDGE - 8PSK modulation scheme - higher peak power PA to support linearity & amplitude,EDGE Coding Schemes and Power Requirements,GPRS and GMSK Modulation,EDGE and 8PSK Modulation,采用3/8可以避免过零点和控制带宽。,EDGE基本特点,GPRS/EDGE无线块结构,GPRS无线块结构,EGPRS无线块结构,GPRS 和 EGPRS的无线块结构,Overview o
14、f EGPRS: Key Features,In MCS7-9, an EGPRS radio block includes two RLC data blocks not linked with each other,传送4个Payload时，采用两个RLC块(不同的序列号和块检验序列)。,Header Format,To ensure strong header protection, the header part of the Radio Block is independently coded from the data part of the Radio Block (8 bit
15、CRC calculated over the header -excl. USF- for error detection, followed by rate 1/3 convolutional coding and eventually puncturing- for error correction). Three different header formats are used one for MCS-7, MCS-8 and MCS-9 one for MCS-5 and MCS-6 one for MCS-1 to MCS-4. The two first formats are
16、 for 8PSK modes, the difference being in the number of Sequence Numbers carried (2 for MCS-7, -8 and -9, 1 for MCS-5 and 6). The third format is common to all GMSK modes. The header is always interleaved over four bursts.,Overview of EGPRS: Key Features,MCS-9,Overview of EGPRS: Key Features,MCS-6,Co
17、ding and puncturing for MCS-4; uncoded GMSK, one RLC block per 20 ms,Overview of EGPRS: Key Features,EDGE关键技术,Overview of EGPRS: Key Features,New modulation 8PSK (3 bit coded in one symbol) and GMSK Coding schemes Nine coding schemes with varying degree of protections Code Families enabling re-segme
18、ntation Header and data coded with different coding schemes,Incremental Redundancy,初始数据接收,重传数据的接收,Incremental Redundancy - 1,With EGPRS resegmentation is possible: packets sent with little error protection can be retransmitted with more error protection Send redundancy only if necessary Generalized
19、Type-II ARQ Finer granularity of code rateExample -MCS9,有用信息,EDGE族,根据使用的基本有效载荷单元(Payload)数目的不同，MCS可以分为A、B和C三个家族。它们所使用的有效载荷单元分别为37(和34)、28和22字节。各家族中的无线块通过传送不同数目的有效载荷单元获得不同编码速率。A和B家族中无线块可以传送1、2或者4个有效载荷单元，C家族中无线块则只传送1个或者2个有效载荷单元。,Family A Padding,EGPRS编码方式下的编码参数,新的MCS下RLC数据块的重传,RLC数据块首先采用一种初始码率进行发送(如采用
20、所选MCS的1/3编码方式和PS1穿孔机制)。如果RLC数据块需要重传，将采用特定MCS的PS2穿孔方式进行传送，并与先前接收到的数据包一同解码，直到数据块成功解码为止。如果所有的码字(编码数据块的不同穿孔机制)都已被发送，将从第一个码字(采用PS1穿孔) 发送，接着采用PS2等等，重复进行发送。,Puncturing Scheme Selection,Overview of EGPRS: Key Features,Link Adaptation (LA)根据链路质量进行UL/DL编码方式的选择,Overview of EGPRS: Key Features,LA没有明确的标准。一般采用质量标
21、准。 BLEREGPRS中引入三个新的质量测试项(GMSK和8PSK分别报告)。目的是为了提高BLER估算的准确性。MEAN_BEP：每个Block(4个突发)上的Bit Error Probability。为MS所在时隙上的无线块的平均值。发送周期由BEP_Period参数设定。32个值， CV_BEPBEP的coefficient variation 。CV-BEP = std(BEP)/MEAN_BEP3比特，8个值。 MEAN_BEP per TS单个时隙上的BEP值。16个值。由网络决定是否需要进行报告。,MEAN_BEP mapping and accuracy,Coefficie
22、nt of Variation mapping table,8PSK MCS selection based on BEP reports,GMSK Modulation Coding Scheme Selection,BEP_Period和BEP_Period2,BEP_PERIOD2=15,则采用e1;如果BEP_PERIOD2 15, 则采用e2.,Overview of EGPRS: Key Features,RLC receive window size 4Rx timeslots: 64 to 512 8Rx timeslots: up to 1024 RLC window siz
23、e is allocated during the TBF establishment This windows size is used for Incremental Redundancy and for RLC processing as for GPRS,Overview of EGPRS: Key Features: MS Aspects,Maximum downlink MS multislot support MS class 8 4Rx and 1 simultaneous Tx timeslotMaximum uplink MS multislot support MS cl
24、ass 11 and 12 3Tx and 2 simultaneous Rx timeslotsMaximum uplink multislot usage 3 Tx Extended dynamic allocation required to support 3 Tx 4 Tx timeslots in question due to specification issue Unlikely to have more than 3 Tx timeslots in 2G networks,EDGE性能,3D surface throughput vs. bep vs. cv_bep,EDG
25、E Coding Schemes - 3,EDGE Coding Schemes throughputs for different Carrier-to-Interference ratio (C/I).,EDGE Coding Schemes - 4,Downlink throughput versus path-loss distance benefits from higher C/I of EDGE.,IR的好处,EDGE Coding Schemes - 5,EDGE data rates are about 3 times the GPRS ones. As shown in the following chart. The “secret” is to use the right coding scheme in each different condition:,
