Transmit Power Control (TPC)
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Transmit Power Control (TPC)
- TPC is used to regulate the power levels used by OFDM radio cards in the 5 GHz frequency bands.
- The ERC mandates that radio cards operating in the 5 GHz band use TPC to abide by a maximum regulatory transmit power and are able to alleviate transmission power to avoid interference.
- The TPC service is used to meet the regulatory transmission power requirements.
- TPC is required to protect the Earth exploration satellite service.
- The transmit power control (TPC) service provides for the following:
- Client stations can associate with an AP based on their transmit power.
- Designation of the maximum transmit power levels permitted on a channel, as permitted by regulations.
- An AP can specify the transmit power of any or all stations that are associated with the AP.
- An AP can change transmission power on stations based on factors of the physical RF environment such as path loss.
- The information used by both DFS and TPC is exchanged between client stations and APs inside of management frames.
- The 802.11h amendment effectively introduced two major enhancements:
- More frequency space with the introduction of the U-NII-2 Extended band
- Radar avoidance and detection technologies
- The ratified 802.11k amendment does make it possible for an AP to inform clients to use transmit power control (TPC) capabilities to change their transmit amplitude dynamically to match the AP’s power. However, most clients do not yet support 802.11k mechanisms.
Reference:
Coleman, David D.,Westcott, David A. CWNA: Certified Wireless Network Administrator Official Study Guide: Exam CWNA-106 Wiley.
Coleman, David D.,Westcott, David A. CWNA: Certified Wireless Network Administrator Official Study Guide: Exam CWNA-106 Wiley.
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