3GPP HSDPA中引入了Channel quality indicator (CQI)的感念,一直感觉非常的神奇!因为他改变了传统数据下载的理念,可以根据实际信道的质量调节信道数量,调制方式,控制功率等方式调整下载速率,给信道质量好的用户分配更多的资源。
3GPP
25331中,影响CQI的上报规则参数主要有3个:
feedback-cycle fc2,
//CQI反馈周期
,单位2ms. 取值:(0, 2, 4, 8, 10, 20, 40, 80, 160) MS
cqi-RepetitionFactor 1
//CQI上报重复因子,取值:(1, 2, 3, 4)
deltaCQI 5
//功率控制,取值:(0,…,8)
但具体的用法在3GPP 25214中有说明:
CQI的取值范围在0~30,当CQI 值为31时,表明当前CQI没有定义(没有上报CQI)
关于CQI的描述在文档:3GPP 25.214中:6A.2.3
给出了CQI 的tables
Category | Used CQI mapping table |
MIMO not configured | MIMO configured and single-stream restriction not configured | MIMO and single-stream restriction configured |
64QAM not configured | 64QAM configured | 64QAM not configured | 64QAM configured | 64QAM not configured | 64QAM configured |
In case of type B or single transport block type A CQI reports | In case of dual transport block type A CQI reports | In case of type B or single transport block type A CQI reports | In case of dual transport block type A CQI reports | | |
1-6 | A | N/A | A | N/A |
7 and 8 | B | N/A | B | N/A |
9 | C | N/A | C | N/A |
10 | D | N/A | D | N/A |
11 and 12 | E | N/A |
13 | C | F | N/A | C | F |
14 | D | G | N/A | D | G |
15 | C | N/A | C | H | N/A |
16 | D | N/A | D | I | N/A |
17 | C | F | C | H | N/A | N/A | F |
18 | D | G | D | I | N/A | N/A | G |
19 | C | F | C | H | F | J | N/A |
20 | D | G | D | I | G | K | N/A |
21 | C | N/A | C | N/A |
22 | D | N/A | D | N/A |
23 | C | F | N/A | C | F |
24 | D | G | N/A | D | G |
25 | C | N/A | C | H | N/A | N/A |
26 | D | N/A | D | I | N/A | N/A |
27 | C | F | C | H | F | J | N/A |
28 | D | G | D | I | G | K | N/A |
29 and 31 | D | G | N/A | D | G |
30 and 32 | D | G | D | I | G | K | N/A |
根据匹配表,可以查看到相关CQI的含义,例如常见的cat10的HSDPA,CQI的取值意义:
CQI or CQIS value | Transport Block Size | Number of
HS-PDSCH | Modulation | Reference power adjustment D | NIR | Xrv or Xrvpb |
0 | N/A | Out of range |
1 | 137 | 1 | QPSK | 0 | 28800 | 0 |
2 | 173 | 1 | QPSK | 0 |
3 | 233 | 1 | QPSK | 0 |
4 | 317 | 1 | QPSK | 0 |
5 | 377 | 1 | QPSK | 0 |
6 | 461 | 1 | QPSK | 0 |
7 | 650 | 2 | QPSK | 0 |
8 | 792 | 2 | QPSK | 0 |
9 | 931 | 2 | QPSK | 0 |
10 | 1262 | 3 | QPSK | 0 |
11 | 1483 | 3 | QPSK | 0 |
12 | 1742 | 3 | QPSK | 0 |
13 | 2279 | 4 | QPSK | 0 |
14 | 2583 | 4 | QPSK | 0 |
15 | 3319 | 5 | QPSK | 0 |
16 | 3565 | 5 | 16-QAM | 0 |
17 | 4189 | 5 | 16-QAM | 0 |
18 | 4664 | 5 | 16-QAM | 0 |
19 | 5287 | 5 | 16-QAM | 0 |
20 | 5887 | 5 | 16-QAM | 0 |
21 | 6554 | 5 | 16-QAM | 0 |
22 | 7168 | 5 | 16-QAM | 0 |
23 | 9719 | 7 | 16-QAM | 0 |
24 | 11418 | 8 | 16-QAM | 0 |
25 | 14411 | 10 | 16-QAM | 0 |
26 | 17237 | 12 | 16-QAM | 0 |
27 | 21754 | 15 | 16-QAM | 0 |
28 | 23370 | 15 | 16-QAM | 0 |
29 | 24222 | 15 | 16-QAM | 0 |
30 | 25558 | 15 | 16-QAM | 0 |
对于终端来说,在HS-PDCCH信道上报CQI值,但何时上报CQI的值,3GPP 25.214中讲了很多,而且公司很复杂,我推算了很长时间,也没有推算出来。但后来根据终端的LOG也进行了一次推算,可能不是很准确,但每次与LOG也都能对的上:
例如:
feedback-cycle fc8, //上报周期为8/2=4
cqi-RepetitionFactor 1
根据LOG,查看当期的帧是否是SFN mode 4 =0,如果是,则上报,否则不上报。
例如实际的LOG:
Base Subframe
= 876
Sample[0].Uncoded Quantized CQI
= 25
//876 mode 4 =0上报
Sample[1].Uncoded Quantized CQI
= No CQI (DTX)
Sample[2].Uncoded Quantized CQI
= No CQI (DTX)
Sample[3].Uncoded Quantized CQI
= No CQI (DTX)
Sample[4].Uncoded Quantized CQI
= 29
//880 mode 4 =0上报
Sample[5].Uncoded Quantized CQI
= No CQI (DTX)
Sample[6].Uncoded Quantized CQI
= No CQI (DTX)
Sample[7].Uncoded Quantized CQI
= No CQI (DTX)
Sample[8].Uncoded Quantized CQI
= 29
Sample[9].Uncoded Quantized CQI
= No CQI (DTX)
Sample[10].Uncoded Quantized CQI = No CQI (DTX)
Sample[11].Uncoded Quantized CQI = No CQI (DTX)
Sample[12].Uncoded Quantized CQI = 27
现在还有一个非常困惑的是cqi-RepetitionFactor
如何使用?在实际测试中发现cqi-RepetitionFactor=1
和cqi-RepetitionFactor=2
的时候,CQI
上报的结果是类似的?究竟如何使用这个参数如何使用,还是不清楚,