doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 1 Aligning e HCF and h TPC Operations Amjad Soomro, Sunghyun Choi, and Javier del Prado Philips Research-USA Briarcliff Manor, New York

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 2 Outline Introduction Transmit Power Control under HCF Proposed rules to improve TPC under HCF

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 3 References IEEE e QoS draft D1.0 IEEE /169r2: DFS and TPC Joint Proposal for h by S. Choi, et al IEEE /373r0: NAV Operation Rules under HCF by J. del Prado, S. Choi, and A. Soomro

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 4 Transmit Power Control (TPC) Mechanism to reduce energy consumption and co-channel interference Adapt the radio transmit power to the minimum level required to ensure correct reception of a frame

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 5 Baseline TGh is working on Transmit Power Control (TPC) 01/169r2 (baseline of.11h) is assuming per- STA power control during CFP and CFB under the HCF operation But...

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 6 TPC under HCF TPC may not be very efficient under the current rules of HCF: –HC needs to hear (i.e., CCA busy) all the frames within its QBSS. Otherwise, it will reclaim the channel after sensing the medium idle for DIFS –HC needs to receive certain frames for the correct operation of the QBSS (e.g., to update TC queue sizes) Inefficiency: in ESTA-to-ESTA communications, the transmit power may not be as low as it could be

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 7 Example Under current rules of HCF, TxOP holder, i.e., ESTA 1, will need to transmit frames so that they can be received by ESTA 2 and at least heard (and preferably received) by the HC. Transmission range of ESTA 1 ESTA-to-ESTA communication: ideal case But the HC need to hear the frames HC ESTA 2 ESTA 1 CCA busy range of ESTA 1 HC ESTA 2 ESTA 1

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 8 Proposed HCF Rules for TPC

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 9 Goal Reduce the energy consumption: –Increase TPC efficiency for direct ESTA-to-ESTA transmissions under HCF

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 10 For the First Frame in a Granted TxOP... CCA busy range of ESTA 1 The TxOP holder shall transmit the first frame in a granted TxOP at a high enough power so that the HC can hear it and the destination ESTA can receive it Use the best power/data rate combination with the above constraint The HC needs to hear the first frame to determine whether the polled ESTA received the QoS CF-poll frame correctly or not Transmission range of ESTA 1 HC ESTA 2 ESTA 1

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 11 For the Subsequent Frames …. Transmission range of ESTA 1 The TxOP holder may transmit at the best power/data rate combination so that the destination ESTA can receive the frame correctly To update the TC queue size, or update or request a new TxOP, the TxOP holder should transmit at a power/data rate combination so that both the destination ESTA and the HC can receive the frame correctly HC ESTA 2 ESTA 1

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 12 For Last Frames in a Granted TxOP... Transmission range of ESTA 1 An ESTA should transmit at least the following types of frames at a power/data rate combination to be received by both the HC and the destination ESTA: –QoS data frame with NF=0 –QoS CF-ACK responding to the QoS frame with NF=0. Desirable to save bandwidth, especially when the TxOP holder finishes earlier than the originally granted TxOP HC ESTA 2 ESTA 1

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 13 HC Reclaim Operation Rules The HC can reclaim the channel only in the following situations: –When the CCA stays idle for PIFS time immediately after the end of the QoS CF- Poll frame –Upon reception of a frame from the TxOP holder with NF=0 and a relevant QoS CF-ACK frame if the normal ACK policy is used –The granted TxOP expires Note that the HC cannot reclaim the channel after sensing the medium idle for DIFS unconditionally –The first difference from e D1.0

doc.: IEEE /412r0 Submission S. Choi, Philips Research July 2001 Slide 14 During a TxOP, only the TxOP holder is responsible for recovery from the absence of an expected reception. –The second difference from e D1.0 The recovery can be done by: –Retransmiting the frame –Sending a frame to another ESTA –Sending a QoS Null Data to the HC with the NF bit equal to 0 (In this manner, the TxOP ends and the HC can reclaim the channel) All other ESTAs, including the HC, shall not initiate channel recovery since they cannot determine if the TXOP holder is transmitting/receiving a frame or not Recovery Rules