lte接入专题优化

… 152, 687, 144, 695, 134, 705, 138, 701, 199, 640, 162, 677, 176, 663, 119 720, 158, 681, 164, 675, 174, 665, 171, 668, 170, 669, 87, 752, 169, 670, 88, 751, 107, 732, 81, 758, 82, 757, 100, 739, 98, 741, 71, 768, 59, 780, 65, 774, 50, 789, 49, 790, 26, 813, 17, 822, 13, 826, 6, 833 … 225, 614, 224, 615, 221, 618, 220, 619, 127, 712, 147, 692, 124, 715, 193, 646, 205, 634, 206, 633, 116, 723, 160, 679, 186, 653, 167, 672, 79, 760, 85, 754, 77, 762, 92, 747, 58, 781, 62, 777, 69, 770, 54, 785, 36, 803, 32, 807, 25, 814, 18, 821, 11, 828, 4, 835 3, 836, 19, 820, 22, 817, 41, 798, 38, 801, 44, 795, 52, 787, 45, 794, 63, 776, 67, 772, 72, 767, 76, 763, 94, 745, 102, 737, 90, 749, 109, 730, 165, 674, 111, 728, 209, 630, 204, 635, 117, 722, 188, 651, 159, 680, 198, 641, 113, 726, 183, 656, 180, 659, 177, 662, 196, 643, 155, 684, 214, 625, 126, 713, 131, 708, 219, 620, 222, 617, 226, 613 … 336, 503, 305, 534, 373, 466, 280, 559, 279, 560, 419, 420, 240, 599, 258, 581, 229, 610
小区属性
Cell High-speed Attribute 缺省值：Not high speed cell
ENUMERATE { Not high speed cell, high speed cell}
终端最大发射功率
Biblioteka Baidu
小区半径
一般建议城区使用低速，开阔地或移动台能够 高速移动（如80Km/h~120Km/h）的区域可配置 为高速。
7.37
9.80 12.23 15.95 22.82 38.84 58.86
14
11 9 7 5 3 2
5
6 8 10 13 22 32
82
100 128 158 202 237 -
10.66
13.23 17.23 21.52 27.81 32.82 -
10
8 6 5 4 3
7
8 11 13 16 22
1
Sent on PRACH with RA-RNTI Random Access Response RAP sent on PDSCH, addressed by PDCCH using RA-RNTI Scheduled Transmission
2
3
Data sent on PUSCH Contention resolution CR sent on PDSCH, addressed by PDCCH using TC/C-RNTI
小区半径 (km)
每个前导 中的Ncs
根u 个数
小区半径 (km)
每个前导 中的Ncs
根u 个数
0 1
0 13
118.93 0.79
1 64
64 1
15 18
1.08 1.51
55 46
2 2
2
3 4 5 6 7 8
15
18 22 26 32 38 46
1.08
1.51 2.08 2.65 3.51 4.37 5.51
0–23
Physical root sequence number u (in increasing order of the corresponding logical sequence number)
129, 710, 140, 699, 120, 719, 210, 629, 168, 671, 84, 755, 105, 734, 93, 746, 70, 769, 60, 779 2, 837, 1, 838 56, 783, 112, 727, 148, 691
PRACH前导生成
Logical Root Sequence Start Number Used to Generate PRACH [0..837] 缺省值：无
Table Root Zadoff-Chu sequence order for preamble formats 0 – 3
Logical root sequence number
2
3
内容
• • • • • 接入流程 接入相关参数 接入相关KPI 接入常用优化方法 典型接入失败案例分析
接入相关参数
Cell High-speed Attribute小区高速移动属性 Ncs Used to Generate PRACH Preamble用于生成PRACH前导的循环位移参数Ncs Logical Root Sequence Start Number Used to Generate PRACH Preamble用于生成 PRACH前导的逻辑根序列起始索引号 Number of Non-dedicated Random Access Preambles竞争随机接入前导个数 Size of Random Access Preambles Group A前导组A中的前导个数 Threshold of Selecting Preamble Group选择随机接入前导组的门限（消息的长度） Message Power Offset for Group B 组B配置的功率余量 the Initial RB Number for Random Access Preambles 随机接入前导的起始RB号 PRACH Configuration Index PRACH配置索引 Initial Power for Preamble of PRACH PRACH前导初始发射功率 Power Ramping Step for PRACH PRACH的功率攀升步长 Max retransmit number for PRACH PRACH前导最大重传次数 TTI Window Size for PRACH Response UE对随机接入前导响应接收的搜索窗口 Max Number of Messages HARQ Transmissions Message 3 最大发送次数 MAC Contention Resolution Timer MAC冲突解决定时器 Dedicated Preamble Life Time专用前导资源占用时间
4
基于非竞争的随机接入—专用前导
UE
Msg0: PDCCH order Dedicated Preamble ID, Mask Index Msg1: Random Access Preamble
eNodeB
0
1
Dedicated preamble Msg2: RA Response sent on PDSCH Msg3: Contention requirement Data or padding
PRACH前导生成
Ncs Used to Generate PRACH Preamble [1..11] 缺省值：10
Table N CS for preamble generation (preamble formats 0-3).
Ncs configuratio n 中低速场 景Ncs (<) 高速场景 Ncs (≥)
Setup Default EPS Initial Context Bearer Setup Request
Initial Context Setup Response Uplink NAS Transport
基于竞争的随机接入—冲突解决
UE
Random Access Preamble
eNodeB
eNodeB
EPC
18. UE Context Release Command
19. RRC Connection Release
20. UE Context Release Complete
UE UE
Msg 1
RA Preamble
eNB eNB L1 PHY
eNB L2
L2
Preamble ID Ra-Rnti
eNB L3
L3
EPC
EPS
Apply C-Rnti Allocate Temporary C-Rnti Setup SRB0
RA Response
Msg 2
Msg 3
RRC Connection Request
SRB0
Setup SRB1
RRC Connection Setup RRC Connection Setup Complete Identity/Authentication/Security
湖北电信CD级 无线人才培训教材
LTE接入优化
内容
• • • • • 接入流程 接入相关参数 接入相关KPI 接入常用优化方法 典型接入失败案例分析
随机接入的5种场景
场景1：初始接入 和RRC Idle向 RRC Connected 转移
场景5：上行失步 时上行数据到达
场景2：无线链路 失败的重建立
eNodeB
EPC
5. RRCConnectionSetupComplete (包含Service Reques消息）
6. Initial UE message (包含Service Reques消息）
7. Authentication
建立EPS 默认承载
随机接入流程（2）
UE
9. UECapabilityEnquiry
14. RRCConnectionReconfiguration
建立SRB2 和DRB
15. RRCConnectionReconfigurationComplete 16. S1-AP: Initial Context Setup Response
随机接入流程（3）
UE
First Uplink Data First Downlink Data 检测到User Inactivity 17. UE Context Release Request (Cause) 更新承载 更新承载
eNodeB
EPC
8. S1-AP: Initial Context Setup Request
10. UECapabilityInfomation
11. UE Capability Info Indication 12. SecurityModeCommand 13. SecurityModeComplete
Msg 4 SRB1
Initial UE Message
Msg 5
UE Capability Enquiry/Info Security Mode Command Security Mode Complete Setup SRB2&DRB RRC Connection Reconfiguration RRC Connection Reconfiguration Complete UL Info Transfer Data
场景4：上行失步 时下行数据到达
场景3：切换后接 入新小区
随机接入流程（1）
UE
Idle状态下有数据或信令发送， 发起service reques过程 1. RA Preamble 2. RA Response 3. RRCConnectionRequest 4. RRCConnectionSetup 建立 SRB1
55
46 38 32 26 22 18
2
2 2 2 3 3 4
22
26 32 38 46 55 68
2.08
2.65 3.51 4.37 5.51 6.80 8.66
38
32 26 22 18 15 12
2
2 3 3 4 5 6
9
10 11 12 13 14 15
59
76 93 119 167 279 419