802.11n MCS Guide

MCS (modulation and Coding scheme, modulation and encoding strategy)

The configuration of the 802.11n RF rate is achieved through the MCS index values. The MCS modulation encoding table is a representation of the 802.11n to characterize the communication rate of the WLAN. MCS takes the factors that affect the communication rate as columns of the table, and the MCS index as rows, forming a rate table.

Therefore, each MCS index actually corresponds to the physical transfer rate under a set of parameters, and table 1-4 and table 1-5 respectively enumerate the MCS rate tables with a bandwidth of 20MHz and a bandwidth of 40MHz.

(The full rate description can be found in the contents of the 20.6 Parameters for HT MCSs section of the document "802.11n-2009". ）

We can conclude from the following table that the MCS 0~7 uses a single spatial flow, and when mcs=7, the rate value is the largest. The MCS 8~15 uses two spatial streams, with the highest rate value when mcs=15.

Table 1 MCS corresponding rate table (20MHz )

MCS Index	Number of spatial flows	Modulation mode	Rate (MB/s)
			800ns GI	400ns GI
0	1	Bpsk	6.5	7.2
1	1	Qpsk	13.0	14.4
2	1	Qpsk	19.5	21.7
3	1	16-qam	26.0	28.9
4	1	16-qam	39.0	43.3
5	1	64-qam	52.0	57.8
6	1	64-qam	58.5	65.0
7	1	64-qam	65.0	72.2
8	2	Bpsk	13.0	14.4
9	2	Qpsk	26.0	28.9
10	2	Qpsk	39.0	43.3
11	2	16-qam	52.0	57.8
12	2	16-qam	78.0	86.7
13	2	64-qam	104.0	115.6
14	2	64-qam	117.0	130.0
15	2	64-qam	130.0	144.4

Table 2 MCS corresponding rate table (40MHz )

MCS Index	Number of spatial flows	Modulation mode	Rate (MB/s)
			800ns GI	400ns GI
0	1	Bpsk	13.5	15.0
1	1	Qpsk	27.0	30.0
2	1	Qpsk	40.5	45.0
3	1	16-qam	54.0	60.0
4	1	16-qam	81.0	90.0
5	1	64-qam	108.0	120.0
6	1	64-qam	121.5	135.0
7	1	64-qam	135.0	150.0
8	2	Bpsk	27.0	30.0
9	2	Qpsk	54.0	60.0
10	2	Qpsk	81.0	90.0
11	2	16-qam	108.0	120.0
12	2	16-qam	162.0	180.0
13	2	64-qam	216.0	240.0
14	2	64-qam	243.0	270.0
15	2	64-qam	270.0	300.0

MCS is divided into two categories: The basic MCS set and the MCS set.

Basic MCS set: The basic MCS is the set of MCS rates that must be supported for the AP to work properly, and the client must meet the basic MCS rate configured by the AP to be able to associate with the AP.

L Support MCS set: the support MCS rate set is based on the base MCS set of the AP, the higher rate set that the AP can support, and the user can configure the MCS rate set to enable the client to select a higher rate to associate with the AP, with the prerequisite of meeting the basic MCS.

It is important to note that when you configure the MCS index value, the input MCS index value represents a range, that is, the 0~ configuration value, such as input 5, that specifies that the MCS value set is 0~5.

# includes MCS tables with 1, 2, 3, 4 space streams

# 802.11n & 802.11ac MCS

5. References

1, "802.11n:a.survival.guide (2012.4)]. Matthew.gast "chapter3-802.11n speed

2. IEEE 802.11n Specification "802.11n-2009": 20.6 Parameters for HT MCSs

3. H3C "03-wlan RRM Configuration"

Http://www.h3c.com.cn/Service/Document_Center/Routers/Catalog/MSR/MSR_50/Configure/Operation_Manual/H3C_MSR_ cg-r2207 (V1.11)/13/201212/768510_30005_0.htm#_toc298161643

4.802.11n Key Technology

Http://www.h3c.com.cn/MiniSite/H3C_TechOnline/Wlan_Subject/Hot_Point/Technology_Hot/biaozhun/200906/638149_97665_0.htm

802.11n MCS Guide