EGPRS PAR 相关参数介绍.pdf

NetworksNetworks EGPRS EGPRS 相关参数介绍相关参数介绍 BSC LEVELBSC LEVEL 2 2005 Nokia V1 Filename ppt yyyy mm dd Initials 3 2005 Nokia V1 Filename ppt yyyy mm dd Initials GTUGTGTUGT BSC Level GPRS territory update guard time GTUGT Q3 name terrUpdateGuardTimeGPRS Modification Online Range 1 255 s MML default 5 Description With this parameter you set the timer which must elapse between two subsequent territory updates Related command s EEN EEO Recommended value default Planning Too high value causes low throughput the time is too long to wait for triggering territory update while too low value can generates high signaling MNDLMNDL 4 2005 Nokia V1 Filename ppt yyyy mm dd Initials BSC Level Maximum number of DL TBF MNDL Q3 name PcuMaxNoDLtbfInCH Modification Online Range 1 9 MML default 9 Description With this parameter you define the maximum number of TBFs that a radio time slot can have in average in a GPRS territory in the downlink direction Related command s EEQ EEO Recommended value default Planning There is no any reason to reduce this paremeter from 9 to lower value MNULMNUL 5 2005 Nokia V1 Filename ppt yyyy mm dd Initials Maximum number of UL TBF MNUL Q3 name PcuMaxNoULtbfInCH Modification Online Range 1 7 MML default 7 Description With this parameter you define the maximum number of TBFs that a radio time slot can have in average in a GPRS territory in the uplink direction Related command s EEQ EEO Recommended value default Planning There is not any reason to reduce this parameter from 7 to lower value These parameters cannot have values higher than nine and seven respectively This restriction is brought about by the number of available timing advance indexes and USF values the number of available USF values limits the number of UL TBFs to seven per timeslot the number of available timing advance indexes is 16 including both UL and DL TBFs which means that the maximum number of UL TBFs being seven there can be at most nine DL TBFs BSC Level MNDLMNDL 6 2005 Nokia V1 Filename ppt yyyy mm dd Initials Maximum number of DL TBF MNDL Q3 name PcuMaxNoDLtbfInCH Modification Online Range 1 9 MML default 9 Description With this parameter you define the maximum number of TBFs that a radio time slot can have in average in a GPRS territory in the downlink direction Related command s EEQ EEO Recommended value default Planning There is no any reason to reduce this paremeter from 9 to lower value BSC Level CSUCSU 7 2005 Nokia V1 Filename ppt yyyy mm dd Initials Free TSL for CS upgrade CSU Q3 name FreeTSLsCsUpgrade Modification Online Range 0 10 s MML default 4 Description With this parameter you define a period following a GPRS upgrade during which the probability for a GPRS downgrade in a BTS should be no more than 5 Based on the given time and the size of a BTS number of TRXs the BSC defines a margin of idle TSLs that is required as a condition for starting a GPRS territory upgrade in the BTS A GPRS upgrade may be done if the number of free TSLs in a BTS is at least equal to the defined margin still after the upgrade In the margin definition the BSC uses a table that is shown in GPRS territory upgrade of GPRS in BSC Related command s EEM EEO Recommended value default BSC Level Free TSL for CS upgrade CSU With this parameter you define a period following a GPRS upgrade during which the probability for a GPRS downgrade in a BTS should be no more than 5 Default value for the period length is 4 4 seconds seconds BSC Level CSDCSD 9 2005 Nokia V1 Filename ppt yyyy mm dd Initials Free TSL for CS downgrade CSD Q3 name FreeTSLsCsDowngrade Modification Online Range 0 100 MML default 95 Description The parameter gives a target probability of TCH availability for circuit switched services in a BTS with GPRS territory Based on the given probability and the size of a BTS number of TRXs the BSC defines a margin of idle TCHs that it tries to maintain free for the incoming circuit switched TCH requests in the BTS If the number of idle TCHs in the circuit switched territory of a BTS decreases below the defined margin a GPRS territory downgrade is started In the margin definition the BSC uses a table that is shown in GPRS territory downgrade of GPRS in BSC Related command s EEM EEO Recommended value default BSC Level Free TSL for CS downgrade CSD That means that if we have 4TRXs cell and at a certain moment we have a decreased number of TSLs for example the number of idle TSLs falls to 1 the associated probability of being free is 93 less than the threshold 95 that means that a GPRS downgrade will be started BSC Level MEMORY OUT FLAG SUM MEMORY OUT FLAG SUM 11 2005 Nokia V1 Filename ppt yyyy mm dd Initials MEMORY OUT FLAG SUM Parameter 046 0046 Value Meaning 0 Deactivates algorithm use Default value s SX 3D Allowed values 0 7D The parameter is used to activate the MS Out of Memory exception procedure in RLC to reduce the number of MCSs used BSC Level RLCRLC确认模式控制参数确认模式控制参数 Acknowledgement Request GPRS Uplink Penalty GPRS Uplink Threshold GPRS Downlink Penalty GPRS Downlink Threshold EGPRS Uplink Penalty EGPRS Uplink Threshold EGPRS Downlink Penalty EGPRS Downlink Threshold Description of EGPRS Downlink These parameters are used by the RLC acknowledgementalgorithmto determine how frequently the PCU polls the mobile station having a DL TBF in EGPRS mode The PCU has a counter which is incremented by one whenever an RLC data block is transmitted for the firsttimeorretransmittedpre emptively The counter is incremented by 1 EGPRS DOWNLINK PENALTY whenever a negatively acknowledged RLC data block is retransmitted The mobilestationispolledwhenthe counter exceeds the threshold value of EGPRS DOWNLINK THRESHOLD TSL Utilization BSC Level 上行上行RLCRLC传送传送 3 1 3 1 1 1 1 1 1 4 5 6 9 21 22 23 RLC data transmission Packet Uplink ACK NACK USF Time PCUPCU MSMS 1010111 111101001 Bitmap 64 Blocks Bitmap 64 Blocks SSN Packet Control ACK NACK Penalty Increment Threshold Total TSL Utilization BSC Level 上行上行RLCRLC传送传送 GPRS Uplink PENALTY 3 GPRS uplink THRESHOLD 22 PCU端对上行RLC的传送有个记数器 收到一个RLC块 就加1 到22后就会发出RLC的 ACK NACK消息 如果中间有些RLC是重传 就会用3加而非1 以加快恶劣情况下的重传确 认 这些详细的RLC重传机制 也给RLC的传送效率留了微调到最优化的余地 原理上 门限 设的最大 中间传送的Poll和Ack也会少 如果无线环境非常好 将提高RLC传送速率 但 是如果无线环境不好 就会加大停顿时间 相反调小了 也会稍微减少传送速度 GPRS与EGPRS有各自的RLC重传参数 14 2005 Nokia V1 Filename ppt yyyy mm dd Initials 3 3 1 3 1 1 1 1 1 1 1 1 Penalty Increment Threshold Total 3 6 9 10 11 12 13 14 15 16 17 18 RLC data block retransmission New RLC data Block RLC data block with poll PCUPCU Packet Downlink ACK NACK Time 1010111 111101001 Bitmap 64 Blocks Bitmap 64 Blocks SSN MSMS 下行下行RLCRLC传送传送 TSL Utilization BSC Level 下行下行RLCRLC传送传送 GPRS DOWNLINK PENALTY 3 GPRS DOWNLINK THRESHOLD 18 PCU端对下行RLC的传送有个记数器 传一个RLC块 就加1 到18后就会发出 poll指令 手机收到后就会发出RLC的ACK NACK消息 如果中间有些RLC是重传 就会用3加而非1 以加快恶劣情况下的重传确认 16 2005 Nokia V1 Filename ppt yyyy mm dd Initials 上下行上下行TBF TBF 释放延迟释放延迟 If there is not any payload RLC MAC block received the TBF will not be released immediately but it can be kept alive for a given time period There are two modifiable parameters related to Delayed TBF feature among PRFILE parameters DL TBF RELEASE DELAY 0 1 5sec def 1s This parameter is used to adjust the delay in downlink TBF release An appropriate delay time increases the system performance since the possibly following uplink TBF can be established faster and frequent releases and re establishments of downlink TBF can be avoided UL TBF RELEASE DELAY 0 1 3sec def 0 5s This parameter is used to adjust the delay in uplink TBF release An appropriate delay time increases the system performance since the possibly following downlink TBF can be established faster Release Delay and BS CV MAX BSC Level 18 2005 Nokia V1 Filename ppt yyyy mm dd Initials 上下行上下行TBF TBF 释放延迟释放延迟 相对于普通的TBF 释放 在NOKIA 的PCU 中提供了TBF 释放延迟功能 通过PCU 中相关参数的控制 在正常需要进行TBF 释放的时刻 PCU 通过特定的机制把相应的TBF 再延续一段时间 参数名称 046 0067 DL TBF RELEASE DELAY 046 0068 UL TBF RELEASE DELAY TBF 释放延迟功能益处 a 由于延迟释放 TBF 的建立可以通过PACCH 进行 加快TBF 建立的速度 b 上下行TBF的指配可以通过PACCH 实现 降低降低CCCH 上负荷 c 减少频繁TBF 建立 释放的可能性 TBF 释放延迟功能负面影响 a 由于存在释放延迟 在一定程度上增加了PCU 负荷 b PCU 在下行发送一些特定的数据块来实现TBF 延迟 某些手机可能无法正常 识别并且响应 这样可能会增加由于手机无响应的TBF drop 次数 c 该功能在上层不稳定 存在时延的情况下有效果 但是无论何种情况下 都 需要上层应用 比如 WAP 的时延不能够超过PCU 中设置的释放时延 否 则本功能不起作用 19 2005 Nokia V1 Filename ppt yyyy mm dd Initials 上行上行TBF TBF 释放延迟原理释放延迟原理 Nokia 上行TBF 延迟释放 PCU 通过延迟发送FAI 1 的上行数据包证实块来实现TBF 释放延迟 和正常情况下的 TBF 释放比较 带来好处如下 普通上行TBF 释放 对于上行TBF 在手机发现数据将会发送完成的时候 手机会启动倒计数过程 在发 送的每一个块中都包含一个CV 值告诉PCU 上行数据发送即将完成 在发送最后一个块 的时候 CV 0 通知PCU 数据发送完成 然后手机启动计时器 等待PCU 发送FAI 1 的 控制块进行TBF 释放 UL TBF Release with Extended UL TBF modeUL TBF Release with Extended UL TBF mode MSBSC PCU Data block with CV 0 EUTM delay timer starts Schedule USF turn for MS UL dummy control block Schedule USF turn for MS UL dummy control block EUTM delay timer expires PACKET UL ACK NACK FAI 1 Polling YES PACKET UL ACK NACK FAI 0 Polling NO PACKET CONTROL ACK UL TBF terminated Data block with CV 1 UL TBF extended state Short description Countdown procedure is ongoing EUTM supporting mobile is allowed to recalculate CV during procedure if it gets more data to send PCU notices this by monitoring Block Sequence Number BSN and Countdown value CV sent by MS After receiving CV 0 block PCU starts UL extended state It sends Packet Uplink Ack Nack message to MS with no Final Ack Indicator FAI on but acknowledging all received blocks During UL extended state PCU schedules USFs for MS according adjustable scheduling rate parameter If MS has no new data to send it sends UL dummy control blocks on its sending turn When UL extended state ends according adjustable release delay parameter PCU sends Packet Uplink Ack Nack message to MS with Final Ack Indicator FAI on UL TBF Schedule Rate Ext Schedule USF turn for MS UL dummy control block MS does not continue TBF Release Delay and BS CV MAX 20 2005 Nokia V1 Filename ppt yyyy mm dd Initials UL TBF Release with Extended UL TBF modeUL TBF Release with Extended UL TBF mode Short description Countdown procedure is ongoing After receiving CV 0 block PCU starts UL extended state It sends Packet Uplink Ack Nack message to MS with no Final Ack Indicator FAI on but acknowledging all received blocks During UL extended state PCU schedules USFs for MS according adjustable scheduling rate parameter If MS has no new data to send it sends UL dummy control blocks on its sending turn When MS gets new data to send during extended state it sends UL data block with new BSN and also new CV value when needed Due BSN PCU knows that new UL LLC is to be sent by MS and UL TBF continues as normally UL TBF extended state MSBSC PCU Data block with CV 0 EUTM delay timer starts Schedule USF turn for MS Data block with new BSN and CV Schedule USF turn for MS UL dummy control block EUTM delay timer stopped TBF continues PACKET UL ACK NACK FAI 0 Polling NO Data block UL TBF Schedule Rate Ext MS continues data transfer on TBF Release Delay and BS CV MAX 21 2005 Nokia V1 Filename ppt yyyy mm dd Initials 22 2005 Nokia V1 Filename ppt yyyy mm dd Initials 下行下行TBF TBF 释放延迟原理释放延迟原理 普通下行TBF 释放 在PCU发现发送最后一个数据块的时候 把其中的判断标志FBI置为1 告诉手机下行数据已 经发送完成 同时PCU 侧也会启动相应的计时器 等待手机回对应的确认消息 进行正式的 TBF释放流程 Nokia 下行TBF 延迟释放 23 2005 Nokia V1 Filename ppt yyyy mm dd Initials GPRS GPRS 网络网络TBF TBF 释放延迟功能测试释放延迟功能测试 为验证TBF 释放延迟功能在网络中实际使用效果 于 11 23 选择 HG1B7 BSC 进行相关测试 通过分别设置不同的参数组合并且针对相关的GPRS 业务进行测试 了解不同参数值对测试结果的影响 同时对比分析参数修 改前和修改后的网络统计指标 掌握网络指标的变化趋势 为最终的优化 参数选择提供有力的依据 在本次测试中 选用的参数组合情况如下 测试地点选择为 国宾 富豪酒店 进行的测试包括 PDP 激活 PING FTP 下载 WAP 登录 图铃下载等 上行释放延迟下行释放延迟 Case I0 51 Case I11 5 Case I1 52 24 2005 Nokia V1 Filename ppt yyyy mm dd Initials 修改修改TBF TBF 释放延迟后信令流程分析释放延迟后信令流程分析 启动正常释放流程启动正常释放流程 开始开始TBF释放时延释放时延 开始开始TBF 释放时延前释放时延前 时延 T 07 247 05 45 2s 25 2005 Nokia V1 Filename ppt yyyy mm dd Initials FTP FTP 测试结果比较测试结果比较 每次各做 每次各做4 4次次FTP FTP 下载 下载 FTP下载应用层速率下载应用层速率 K bytes s 3 60 3 77 3 79 1 94 3 84 3 42 0 001 002 003 004 005 006 00 20051114豪富酒店 log November23 15 36 FUHAO 1 5s log November23 17 24 HAOFU 2s log 20051122国宾酒店 log November23 11 32 GUOBING1 1 5s log November23 19 24 GUOBIN 2s log FTP下载下行平均时隙数量下载下行平均时隙数量 3 0 3 0 3 0 1 9 3 0 2 9 0 00 51 01 52 02 53 0 20051114豪富酒店 log November23 15 36 FUHAO 1 5s log November23 17 24 HAOFU 2s log 20051122国宾酒店 log November23 11 32 GUOBING1 1 5s log November23 19 24 GUOBIN 2s log DL TBF 1 UL TBF 0 5 DL TBF 1 5 UL TBF 1 DL TBF 2 UL TBF 1 5 值逐步增加 结果分析 1 国宾由于测试环 境问题 几次测试之 间占用时隙数目不一 致 2 从富豪酒店来看 随着延迟时间增加 FTP 下载速率有一定 提升 26 2005 Nokia V1 Filename ppt yyyy mm dd Initials PING PING 测试结果比较测试结果比较 每次各做 每次各做4040次次PINGPING测试 测试 结果分析 对于PING 测试 从两个测试点大量的测试 结果来看 随值的增加 PING 时延也逐步 增加 这说明对于PING 这种小业务 并且 ping 的对端地址在本地时延本身就不明显 的情况 该参数不起作用 造成ping时延 增加的主要原因为释放时延长TBF 复用就 越明显 ping平均时间平均时间 1 33 1 42 1 44 1 38 1 40 1 51 0 001 002 003 00 20051114豪富酒店 log November23 15 36 FUHAO 1 5s log November23 17 24 HAOFU 2s log 20051122国宾酒店 log November23 11 32 GUOBING1 1 5s log November23 19 24 GUOBIN 2s log DL TBF 1 UL TBF 0 5 DL TBF 1 5 UL TBF 1 DL TBF 2 UL TBF 1 5 值逐步增加 27 2005 Nokia V1 Filename ppt yyyy mm dd Initials TBF 掉线次数掉线次数 RLC 层吞吐量层吞吐量 下行下行TBF 占用时长占用时长 BSC HG1B7 BSC HG1B7 指标统计指标统计 0 0 5 1 1 5 2 2 5 3 3 5 11221123 11 2211 22 TBF duration ul TBF duration dl 由于延迟释放 下行TBF 占用 时间明显上升 0 5000 10000 15000 20000 25000 30000 35000 11221123 11 2211 22 RCL Payload 由于延迟释放 下行TBF 占用 时间明显上升 0 100 200 300 400 500 600 700 800 11221123 11 2211 22 PS CapacityTerritoryPeak sim tbf ulUL No rspPeak sim tbf dlDL No rsp 由于某些终端支持 原因 造成TBF 掉 线次数上升 28 2005 Nokia V1 Filename ppt yyyy mm dd Initials TBF TBF 释放延迟参数测试总结释放延迟参数测试总结 在PCU 发现将要进行上下行TBF 释放时 会根据相应的算法按设定的参数延迟释放 TBF 对于FTP 测试 随参数值的变大 下载速率有一定程度提升 对于PING 由于本身特点 参数不能够带来性能上提升 对于时延过大的情况 该功能不能够有效的进行处理 更长的时延参数意味着更多 的负荷增加和指标的恶化 实际使用时需要在两者之间寻找一个良好的平衡 目前该参 数最大值不能够超过5s 通过具体测试 目前上行1 秒 下行0 5 秒的释放时延是相对比较优化的推荐值 Practical experience of TBF release delay Practical experience of TBF release delay settingssettings DL release delay 1s can be beneficial for RTT measurements Best values seen with 2 3 s DL release delay Extended UL release delay recommended to be 2 3 sec Rel 4 MS will use EUTM during UL TBF UL TBF release delay can be harmful for PoC if it is larger than 0 5 sec Rel 99 MS will use UL TBF delay if no concurrent DL TBF BSC Level Parameter RecommendationsParameter Recommendations ParameterParameter class id BSS10 5 CD7 default BSS11 CD5 recommendati on BSS11 5 Default BSS11 5 Recommend ation DL TBF RELEASE DELAY46 6703E8 1s 03E8 1s 03E8 1s 03E8 1s UL TBF RELEASE DELAY46 6801F4 0 5s 01F4 0 5s 01F4 0 5s 01F4 0 5s UL TBF RELEASE DELAY EXT46 71 07D0 2s 07D0 2s 07D0 2s UL TBF SCHED RATE EXT46 72 4 80ms 4 80ms 4 80ms BS CV MAX 6999 EGPRS UPLINK PENALTY0001000100010001 EGPRS UPLINK THRESHOLD0019001900190019 EGPRS DOWNLINK PENALTY0001000100010001 EGPRS DOWNLINK THRESHOLD0019001900190019 Source Veli Pekka Ketonen Release Delay and BS CV MAX BSC Level SEG LEVELSEG LEVEL 31 2005 Nokia V1 Filename ppt yyyy mm dd Initials GENAGENA 32 2005 Nokia V1 Filename ppt yyyy mm dd Initials SEG Level GPRS enabled GENA Q3 name GPRSEnabled Modification Online Range Y N MML default N Description With this parameter you define whether the GPRS capability is enabled in the BTS during the normal operation of the cell Related command s EQV EQO Recommended value default Planning The continuous coverage area can be limited by this parameter but E GPRS mobiles will camp on those cells which are selected by C1 C2 or C31 32 parameters GPRSenabled is not checked HYSHYS in the case of the new cell being in a different location area or for a GPRS MS in a different routing area or always for a GPRS MS in ready state in which case the C2 value for the new cell shall exceed the C2 value of the serving cell by at least CELL RESELECT HYSTERESIS dB as defined by the BCCH data from the current serving cell for a period of 5 seconds 33 2005 Nokia V1 Filename ppt yyyy mm dd Initials Link AdaptationLink Adaptation 34 2005 Nokia V1 Filename ppt yyyy mm dd Initials EGPRS link adaptation enabled ELA Q3 name Modification Online Range 0 EGPRS link adaptation is disabled 1 EGPRS link adaptation is enabled for RLC aknowledged mode 2 EGPRS link adaptation is enabled for both RLC aknowledged and RLC unacknowledged modes MML default 2 Description With this parameter you enable or disable EGPRS link adaptation on cell level If disabled the the system uses the MCS value defined by initial MCS for acknowledged mode or initial MCS for unacknowledged mode parameters or a lower MCS Related command s EQV EQO Recommended value default SEG Level MCAMCA 35 2005 Nokia V1 Filename ppt yyyy mm dd Initials SEG Level Initial MCS for acknowledged mode MCA Q3 name initMcsAckMode Modification Online Range 1 to 9 MML default 9 Description With this parameter you indicate the Modulation and Coding Scheme MCS used at the beginning of a TBF for acknowledged mode The parameter is used in EGPRS link adaptation Related command s EQV EQO Recommended value default Planning The initial MCS MCA is an important radio parameter for achieving higher throughput on network level If the network has high C I MCA should be set to 9 If the C I is low less than 12 15 dB the MCA should be set to e g 6 The MCA setting is network and area dependent E GPRS E GPRS网络参数网络参数优化 优化 无线参数无线参数 MCA MCA 在TBF建立的初期 由于MS和BTS都没有收到任何测量报告 MS BTS将使用BTS参数 EGPRS初始 MCS编码方式 来发送 而后在MS开始测量无线接口并且开始向网络侧报告ACK NACK消息后 开始根据BEP和CV的测量值用LA算法来自动调整编码 初始MCS设的过高 会造成初始传输阶段较 高的误块率 特别是在C I较差的区域 初始MCS设的过低 会造成小数据业务传输时延明显增加 传输速率得不到很好的保证 为了更好地从现网中分析EGPRS初始编码方式对不同区域网络性能的影响 特地选取下面市区和县 城各1BSC 进行试验和数据分析 并通过现场CQT测试以及OMC统计数据双方面相结合的方式来分 析和总结在不同EGPRS初始编码方式下对EGPRS网络性能的影响 EGPRSEGPRS初始编码方式参数初始编码方式参数第一套方案第一套方案第二套方案第二套方案第三套方案第三套方案 MCA963 E GPRS E GPRS网络参数网络参数优化 优化 无线参数无线参数 MCA MCA 从现网从现网OMC统计结果来看 统计结果来看 无论是城区还是县城来说MCA 9时给网络带来的整体上下行速率都是最高的 EGPRS初始编码参数设置越小 EGPRS上行BLER也就越小 综合的上行和下行平均每时隙速率还是MCA 9时最高 综合RLC速率和重传率 实际数据传输速率还是MCS9要来的快 对于UL EGPRS TBF建立失败率县城受MCA的设置影响较大 市区则影响不大 从从EGPRS CQT测试结果来看 测试结果来看 对于小数据业务传输时MCA 9具有明显的优越性 缩短了传输的时延 目前EGPRS网络中的主要业务是CMWAP 它的特点就是小数据业务 所以MCA 9的 设置对市区来说能够给网络带来更多的益处 当然 也需要注意到其它BSC对于EGPRS初始编码方式的设置并不一定就是 MCS9是最佳的 这还是要取决于该BSC所在区域的无线情况 具体BSC在参数 调整后还需要进行相关的性能评估 同时 需要注意到速率的增加可能会带来 TBF