MAC header

MAC header

(Media Access Control header) The data fields added at the beginning of a network packet in order to turn it into a frame to be transmitted. A MAC header typically refers to an Ethernet header, which is the predominant network access method in use today. See MAC layer and protocol stack.
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The header structure of the beacon frame includes type, synchronization preamble sequence (SHR-PS), synchronization start of frame Delimiter (SHR-SD), MAC header beacon sequence number (MHR-BSN), destination address, source address, CAP channels and frame check sequence (FCS) as shown in Fig.
We will base our work on the 802.11n standard, given that it is a recommendation that tests and certifies that the equipment comply with the 802.11 standards related to WLAN, thus, thereafter an analysis was made of the type of control made and the components of the MAC header.
Packet length 8192 bits MAC header 272 bits Physical header (PHY) 128 bits ACK 112 bits + PHY header RTS 160 bits + PHY header CTS 112 bits + PHY header sifs 28 us difs 128 us m 6 m' 5 Slot duration 50 us Propagation delay 1 us Channel bit rate 1 Mbps Channel number 3 TABLE 3: The parameter values of the BSA algorithm.
Let [L.sub.DATA] be the average length of DATA packet, [L.sub.DATA] H + E[P], where H is the length of header which composes physical header and MAC header. The transmission durations of DATA and ACK packets are [T.sub.DATA] - [L.sub.DATA]/[R.sub.data]; [T.sub.ACK] [L.sub.ACK]/[R.sub.basic].
Channel parameters Maximum transmission power 100 mW Saturation -90 dBm (minimum signal attenuation threshold) Alpha 3.0 (minimum path loss coefficient) Carrier frequency 2.412 GHz Physical layer parameters Thermal noise -77 dBm Sensitivity -90 dBm Maximum transmission power 100 mW Physical header length 0 bit MAC layer parameters Transmission power 100 mW Bitrate 15360 bit/sec CCA detection time 0.0005s Unit backoff period 40 ms Backoff method exponential MAC header length 24 bits Ack packet length 40 bits Ack wait duration (Ack timeout) 10 ms Neighbour-Ack wait duration 13 ms (neighbour-Ack timeout) SIFS time 192 [micro]s Network layer parameters Network header length 32 bits Application layer parameters Application header length 512 bits
Parameters Value MAC header 272 bits PHY header 192 bits Rate for MAC/PHY header 1 Mbps RTS 352 bits CTS 304 bits ACK 304 bits Slot time 20 [micro]s SIFS 10 [micro]s DIFS 50 [micro]s [CW.sub.min]/[CW.sub.max] 32/1024 FIGURE 2: RE frame format.
The priority information is embedded in the TDMA MAC header. The system will process high priority traffic until it reaches the threshold.
"Packet Modification feature modifies filtered packets using an inband method of conveying information such as Timestamp, Board Serial No., Port No., and Filter No., to the (output port) packet analyzer by carrying this information in the packet's MAC header. The filtered packet's MAC header's Destination MAC Address (6 bytes) and Source MAC Address (6 bytes) fields are modified.
The contents and size of the MAC header depend on the particular MAC layer protocol in use.
Parameter Value Parameter Value Channel bit rate 1Mbps AIFS [3] 5 Average frame size 600 bits AIFS [2] 3 MAC header 224 AIFS [1] 7 PHY header 192 CWmin [4] 7 ACK 112 + PHY header CWmin [3] 15 RTS 160 + PHY header CWmin [2] 31 CTS 112 + PHY header CWmin [1] 31 Slot time 20 [micro]sec CWmax [4] 15 SIFS 10 [micro]sec CWmax [3] 15 DIFS 34 [micro]sec CWmax [2] 1023 AIFS [4] 2 CWmax [1] 1023 TABLE 2: Comparisons between numerical and simulation results on latency (unit: sec).
This frame is constructed from a MAC header (MHR) and a MAC footer (MFR).
where [t.sub.exp] represents total time expenditures for one packet transmission, [t.sub.AIFS]--time required for Distributed Inter Frame Space ([t.sub.AIFS] = 9 x [t.sub.slot] for IEEE 802.11e AC0), CW--Contention Window, [t.sub.slot]--slot time ([t.sub.slot] = 9 [micro]s for OFDM, IEEE 802.11a), [t.sub.packet]--time required for data and overhead transmission consisting of preamble, 30-byte MAC header transmission time--[t.sub.MAC] and 4-byte Frame Check Sequence--[t.sub.FCS]: