SWRU368C May 2018 – January 2021 CC3100 , CC3100MOD , CC3200 , CC3200MOD
The Beacon & Probe response template frame in the MAC is 512 Bytes each; do not add private information elements that will cause the frame to be larger than this limit.
Beacon & Probe response frames include information elements that:
Therefore, the Info Elements that we can add will have different size limit at AP and P2P GO.
If the Probe Response was transmitted by the NWP, the size is limited in case FW transmits the frame. Since we want private IE’s to be identical in all frames, bigger IE’s are not allowed in such cases.
Table 18-2 summarizes all of the fields included in a Beacon & Probe response frames at SimpleLink WiFi device.
AP | P2P | ||||||
---|---|---|---|---|---|---|---|
Name | id | Size | Beacon | Probe | Beacon | Probe | More information |
MAC Header | 24 | 24 | 24 | 24 | 24 | ||
timestamp | 8 | 8 | 8 | 8 | 8 | ||
beacon interval | 2 | 2 | 2 | 2 | 2 | ||
capability info | 2 | 2 | 2 | 2 | 2 | ||
SSID | 0 | 32 | 34 | 34 | 34 | 34 | |
supported rates | 1 | 8 | 10 | 10 | 10 | 10 | |
Direct Seq | 3 | 1 | 3 | 3 | 3 | 3 | |
TIM | 5 | 4 | 6 | 0 | 6 | 0 | |
country | 7 | 6 | 8 | 8 | 8 | 8 | |
ERP | 42 | 1 | 3 | 3 | 3 | 3 | |
EX Rates | 50 | 4 | 6 | 6 | 6 | 6 | |
RSN | 48 | 20 | 22 | 22 | 22 | 22 | 20 in P2P, 24 in AP |
WPA | 221 | 26 | 28 | 28 | 0 | 0 | WPA is not presented in P2P with WPS |
HT capabilities | 45 | 26 | 0 | 0 | 0 | 0 | not set |
HT operation | 61 | 22 | 0 | 0 | 0 | 0 | not set |
WMM | 221 | 24 | 0 | 0 | 26 | 26 | Set in Autonomous P2P GO (due to certification) |
WPS | 221 | 178 | 0 | 0 | 80 | 180 | OUI=0050F2, type=4. only in P2P:78 in beacon, 178 in probe response (depend if config method if presented and on the Device name (up-to 33 chars) |
P2P (wifi direct) | 221 | 61 | 0 | 0 | 20 | 0 | OUI=506F9A, type=9. 18 in beacon, 61 in probe response. Inside Probe response, it is contained only if transmitted by the supplicant. It is not part of Probe Response template!!! |
Summary | 449 | 156 | 150 | 254 | 328 |
As can be seen, Beacon & Probe response frames at AP mode consume 160 bytes.
At P2P GO, Beacon consumes 238 Bytes and Probe Response consumes 348 bytes.
This leaves approximately 350 bytes at AP role for private info elements and approximately 120 bytes at P2P GO role for private info elements.