【正文】 Cisco Systems, Inc. All rights reserved. 89 MCS rates 815 uses two spatial streams Modulation Coding Scheme (MCS rate) determines if the AP is going to send data using one or two spatial streams. This is where you see rate claims as high as 300 Mbps (40 MHz) 169。 2022 Cisco Systems, Inc. All rights reserved. 90 Getting The desired Throughput MCS index of rates GI = 800ns GI = 400ns Number of Rate in Rate in Rate in Rate in MCS spatial Index 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 streams 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 Modulation BPSK QPSK QPSK 16QAM 16QAM 64QAM 64QAM 64QAM BPSK QPSK QPSK 16QAM 16QAM 64QAM 64QAM 64QAM 20MHz 13 26 39 52 65 13 26 39 52 78 104 117 130 40MHz 27 54 81 108 135 27 54 81 108 162 216 243 270 20MHz 7 2/9 14 4/9 21 2/3 28 8/9 43 1/3 57 7/9 65 72 2/9 14 4/9 28 8/9 43 1/3 57 7/9 86 2/3 115 5/9 130 144 4/9 40MHz 15 30 45 60 90 120 135 30 60 90 120 180 240 270 300 169。 2022 Cisco Systems, Inc. All rights reserved. 91 AP1250 Fully Supports MIMO using two transmitters and three receivers Single Input Single Output (SISO) 169。 2022 Cisco Systems, Inc. All rights reserved. Multiple Input Multiple Output (MIMO) 92 Understanding MCS rates and Channel Bonding Channel Bonding: 40MHz channel Wider channels means more BW per AP (not per physical location) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Channels GHz 20 MHz channel GHz MCS rates 015 apply Regardless of channel Bonding. When you bond a channel You have a control channel You have a data (extension) channel Legacy clients use control Channel for munication 169。 2022 Cisco Systems, Inc. All rights reserved. 93 MCS index of rates NSD NCBPS GI = 800ns GI = 400ns MCS Number of spatial Coding Rate in Rate in Rate in Rate in Index 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 streams 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 Modulation BPSK QPSK QPSK 16QAM 16QAM 64QAM 64QAM 64QAM BPSK QPSK QPSK 16QAM 16QAM 64QAM 64QAM 64QAM rate 189。 189。 190。 189。 190。 2/3 190。 5/6 189。 189。 190。 189。 190。 2/3 190。 5/6 20 52 52 52 52 52 52 52 52 52 52 52 52 52 52 52 52 40 108 108 108 108 108 108 108 108 108 108 108 108 108 108 108 108 20MHz 52 104 104 208 208 312 312 312 104 208 208 416 416 624 624 624 40MHz 108 216 216 432 432 648 648 648 216 432 432 864 864 1296 1296 1296 20MHz 13 26 39 52 65 13 26 39 52 78 104 117 130 40MHz 27 54 81 108 135 27 54 81 108 162 216 243 270 20MHz 7 2/9 14 4/9 21 2/3 28 8/9 43 1/3 57 7/9 65 72 2/9 14 4/9 28 8/9 43 1/3 57 7/9 86 2/3 115 5/9 130 144 4/9 40MHz 15 30 45 60 90 120 135 30 60 90 120 180 240 270 300 169。 2022 Cisco Systems, Inc. All rights reserved. 94 GHz, 40 MHz Bandwidths 169。 2022 Cisco Systems, Inc. All rights reserved. 95 Example UNII3 Channel Bonding In 40MHz you define the control channel (this is the channel that is used for munication by Legacy .11a clients. The Extension channel (also defined) is the bonded channel that High Throughput ―HT‖ Clients use in addition to the control channel for higher throughput as they send data on BOTH channels 169。 2022 Cisco Systems, Inc. All rights reserved. 96 Channel Bonding in 5GHz Band Low Channels are Preferred 169。 2022 Cisco Systems, Inc. All rights reserved. 97 Channel Bonding Subcarriers uses both 20MHz and 40MHz channels. The 40MHz channels in are two adjacent 20 MHz channels, bonded together. When using the 40MHz bonded channel, takes advantage of the fact that each 20MHz channel has a small amount of the channel that is reserved at the top and bottom, to reduce interference in those adjacent channels. When using 40MHz channels, the top of the lower channel and the bottom of the upper channel don39。t have to be reserved to avoid interference. These small parts of the channel can now be used to carry information. By using the two 20MHz channels more efficiently in this way, achieves slightly more than doubling the data rate when moving from 20MHz to 40MHz channels 169。 2022 Cisco Systems, Inc. All rights reserved. 98 Understanding Guard Interval The guard interval that is part of each OFDM symbol is a period of time that is used to minimize intersymbol interference. This type of interference is caused in multipath environments when the beginning of a new symbol arrives at the receiver before the end of the last symbol is done. Default mode for is 800 nanoseconds If you set a shorter interval it will go back to long in the event retries occur 169。 2022 Cisco Systems, Inc. All rights reserved. 99 Packet Aggregation (AMSDU and AMPDU) To reduce overhead, introduces frame aggregation. Frame aggregation is essentially putting two or more