n chain The AES algorithm provides the MIC seal and encryption of the MSDU and MIC data. It is supplied by the following values: - AAD (Additional Authentication Data) parameter, built from the MAC header, with the exception of fields that can be modified during a retransmission (e.g. the Duration field); - Nonce parameter, built from the priority byte, the second address contained in the MAC header (A2) and the frame number (PN). The value of the PN field is increased by one unit for each frame generated; - TK. The processing of the CCMP received chain is shown in Figure 2.23. header construction Address 2 Nonce Priority construction Algorithm Clear TK key Ciphered Replay Figure 2.23. CCMP processing of the reception chain Wi-Fi Integration to the 4G Mobile Network The AES algorithm is used to reproduce unscrambled MSDU data. It is supplied by the following values: - AAD parameter; - Nonce parameter; - MIC field to execute an integrity control; - TK. A check on the PN field enables protection from replays. 2.4. Quality of service 2.4.1. EDCA mechanism The EDCA (Enhanced Distributed Channel Access) mechanism is an extension of the DCF mechanism. It is based on the differentiation of user priority (UP) levels. The priority level is the same as that set for the Ethernet frame. The ability to implement the EDCA mechanism is indicated by the access point in the Capability Information field of the BEACON or PROBE RESPONSE management frames. The EDCA mechanism defines four access categories (AC), each category corresponding to a queue (Table 2.3): - a priority level belongs to an access category; - an access category contains two priority levels. TID field User Priority UP Access Category AC Designation AC-BK Background AC-BK Background AC-BE Best Effort AC-BE Best Effort AC-VI Video AC-VI Video AC-VO Voice AC-VO Voice Table 2.3. Correspondence between the priority levels and the access categories MAC Layer The EDCA mechanism defines the parameters used for access to the radio channel: - the arbitration inter-frame spa