 |
善于提问，勤于回答，你也是专家
|
 |
谁知道LTE里面上行峰值速率与下行峰值速率的计算方法？
为什么都是在20MHZ的带宽下，一个是100Mbps一个是50Mbps
我要回答
问题答案
To calculate the the throughput in LTE (for example in DL)
1) number of allocated PRB
2) number of Used RE (resource element in PRB) Some RE is used for RS, CCCH and so on So they are not carrying user data
3) MCS (Modulation type and coding rate which is determined based on CQI)
So for a PRB: # REs is 12*7 (during 1 ms) (just ignore the used REs for CCCH and RS)
in each RE a symbol is send and bits/symbol depends on modulation scheme for 64QAM , 16QAM and QPSK it is respectively 6,4,2
The used coding is also affecting your throughput for example the ratio is 2/3
in the end:
PRB throughput (Kbits/s) ~ 12*7*(bits/symbol)*(Coding ratio)
So in the best condition:
PRB throughput (Kbits/s)=168*6*1 ~ 1008 Kbits/s
e RE
Anyway it is not the approach to calculate the capacity as the used RE for user data could be 80~85% of total available REs
Besides there is no independent resource for signaling and so the PRB is used for user signaling and which another overhead to user DATA throughput
hope my comments help you out
1) number of allocated PRB
2) number of Used RE (resource element in PRB) Some RE is used for RS, CCCH and so on So they are not carrying user data
3) MCS (Modulation type and coding rate which is determined based on CQI)
So for a PRB: # REs is 12*7 (during 1 ms) (just ignore the used REs for CCCH and RS)
in each RE a symbol is send and bits/symbol depends on modulation scheme for 64QAM , 16QAM and QPSK it is respectively 6,4,2
The used coding is also affecting your throughput for example the ratio is 2/3
in the end:
PRB throughput (Kbits/s) ~ 12*7*(bits/symbol)*(Coding ratio)
So in the best condition:
PRB throughput (Kbits/s)=168*6*1 ~ 1008 Kbits/s
e RE
Anyway it is not the approach to calculate the capacity as the used RE for user data could be 80~85% of total available REs
Besides there is no independent resource for signaling and so the PRB is used for user signaling and which another overhead to user DATA throughput
hope my comments help you out
回答者：kevinh 回答时间：2013-05-16 13:09
27
28那上行的又是怎么算出来的呢？这样说的话上行也可以用64QAM，算出来峰值速率不也是100.8Mbps，为什么上行的是下行的一半？难道是调制方式不一样
回答者：dnn 回答时间：2013-05-16 22:09
上下行UE支持的最大TBS块大小是不同的（或者说MCS等级上下行是不一样的），而且下行在计算最大值时还考虑了双流波束赋形，上行是没有的。
上面几点就使得上下行峰值速率计算结果不同。
上面几点就使得上下行峰值速率计算结果不同。
回答者：marinelick 回答时间：2013-05-18 08:08
那上面计算的下行峰值速率12*7*6*100*2=100.8Mbps,哪里能体现下行是双流呢？那个又表示的是TBS的大小？3GPP协议里面说上行峰值速率是50Mbps,不知道这个是怎么计算出来的？
