Beacon Frame
commwlan80211Beacon:
[mpduHeader, mpduBody] = getBeaconMPDU(TSF, p80211);
关于getBeaconMPDU函数说明：
getBeaconMPDU Form a beacon frame MPDU
[H,B] = getBeaconMPDU(T,P) returns a beacon frame MPDU for the 802.11
WLAN Beacon Frame example. T represents the simulation time in
milliseconds and P represents the parameter structure for the 802.11
system. H and B are structures that contain the beacon frame header and
body.
Reference: IEEE Std 802.11-2007, Section 7.2.3.1 Beacon frame format
首先看下p80211结构：
p80211 =
包含以下字段的 struct:
SymbolRate: 1000000
BitsPerSymbol: 1
SamplesPerChip: 4
FilterOrder: 8
SpreadingCode: [11×1 double]
SpreadingRate: 11
ChipRate: 11000000
SynchronizationSignal: [5632×1 double]
CorrelationThreshold: 281.6000
SYNC: [128×1 logical]
SFD: [16×1 logical]
SIGNAL: [8×1 logical]
SERVICE: [8×1 logical]
LENGTH: [1×16 logical]
CRCLength: 16
ScramblerPolynomial: [1×8 double]
ScramblerAmbiguity: 128
ScramblerAmbiguitySamples: 5632
NumSYNCSamples: 5632
PLCPPreambleLength: 144
NumPLCPPreambleSamples: 6336
PLCPHeaderLength: 48
NumPLCPHeaderSamples: 2112
PLCPLength: 192
NumPLCPSamples: 8448
MaximumPPDULength: 1024
MaximumMPDULength: 832
SymbolsPerChannelFrame: 128
BitsPerChannelFrame: 128
SamplesPerChannelFrame: 5632
MaximumPayloadSymbols: 3000
MaximumPayloadSamples: 132000
PayloadBufferLength: 3256
BeaconInterval: 2
SSID: [1×9 uint8]
SupportedRates: [1 2]
ChannelNumber: 11
SendCFParameters: 1
CFPCount: 2
CFPPeriod: 20
CFPMaxDuration: 10
CFPDurRemaining: 5
NumMPDUOctets: 62
再看看mpduHeader：
mpduHeader =
包含以下字段的 struct:
FrameCtrl: [1×1 struct]
DurationID: [61 9]
Address1: [180 156 233 168 94 246]
Address2: [19 39 221 39 76 35]
Address3: [176 172 79 142 6 73]
SequenceControl: [179 1]
Address4: [0 0 0 0 0 0]
打开FrameCtrl：
包含以下字段的 struct:
ProtocolVersion: 0
Type: 0
Subtype: 8
ToDS: 0
FromDS: 0
MoreFragments: 0
Retry: 0
PowerManagement: 1
MoreData: 0
ProtectedFrame: 0
Order: 1
再看看body部分：
mpduBody =
包含以下字段的 struct:
TimeStamp: [0 0 0 0 0 0 0 0]
BeaconInterval: [2 0]
Capability: [1×1 struct]
InfoElements: [1×25 struct]
NumInfoElements: 4
打开Capability：
mpduBody.Capability
ans =
包含以下字段的 struct:
ESS: 1
IBSS: 0
CFPollable: 0
CFPollRequest: 1
Privacy: 0
ShortPreamble: 1
PBCC: 1
ChannelAgility: 0
SpectrumManagement: 0
QoS: 0
ShortSlotTime: 1
APSD: 0
Reserved: 0
DSSOFDM: 1
DelayedBlockAck: 0
ImmediateBlockAck: 1
payload:
payload =
832×1 uint8 列矢量
128
144
61
9
180
156
233
168
94
246
19
39
221
39
76
35
176
172
79
142
6
73
179
1 //mpduHeader到这里结束，下面是mpduBody开始
0
0
0
0
0
0
0
0 //上述8个0位置记录timestamp
2
0 //上述2个为BeaconInterval
105
164 //上述2个为mpduBody.Capability的封装
0 //id
9 //下面内容长度包含9个位置
87
108
97
110
32
116
101
115
116 //第一部分结束------这部分记录的是wlan的SSID
1
2
130
132 //第二部分结束------这部分记录的是Supported Rates
3
1
1 //第三部分结束------这部分记录的是DS Parameters
4
6
2
20
10
0
5
0 //第四部分结束------这部分记录的是CF Parameters
0
0
0
0
0
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