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HCCA TXOP handling difficulties

HCCA TXOP handling difficulties. Jarkko Kneckt Nokia. Referred comments. BARR/14, Hansen/2. Scheduled APSD use with HCCA during CFP.

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HCCA TXOP handling difficulties

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  1. HCCA TXOP handling difficulties Jarkko Kneckt Nokia Jarkko Kneckt, Nokia

  2. Referred comments • BARR/14, Hansen/2 Jarkko Kneckt, Nokia

  3. Scheduled APSD use with HCCA during CFP • HCCA can be used during contention free periods, CFP. The APSD instructions in sections 11.2.1.5 and 11.2.1.7 refer to operation in contention period, CP. The non-AP QSTA shall be able to use scheduled APSD power save with HCCA also during CFPs. Jarkko Kneckt, Nokia

  4. EOSP use in QoS-CF ACK frame, or with packet QoS+CF ACK frame • 11.2.1.5, section j says: If the QAP does not receive an acknowledgement to a directed MPDU or management frame sent with the EOSP subfield set to 1, it shall retransmit that frame at least once within the same service period - subject to applicable retry or lifetime limit. Table 1 in page 22 lists QoS CF-ACK frame to data frame. • Can QoS Cf-ACK frame have set EOSP bit? • Must QoS Cf-ACK with set EOSP bit be acknowledged? With EDCA the EOSP bit can be set in Data and Null frames, which are acknowledged according to section 11.2.1.5, j). Jarkko Kneckt, Nokia

  5. EOSP and NAV/duration field dependence • Does CF-ACK with set EOSP bit terminate both TXOP and HCCA service period? Or can terminal continue HCCA TXOP by transmitting a frame? • If EOSP terminates also the TXOP, should Duration / id field be set appropriately? Jarkko Kneckt, Nokia

  6. Q-ACK option and set EOSP in QoS Cf-POLL+CF-ACK frame Q-ACK option is used. QoS + CF POLL+CF ACK frame contains set EOSP bit. Does the EOSP bit refer to non-AP QSTA 2, who is receiving QoS CF-poll frame or the non-AP QSTA1 from previous TXOP who is receiving QoS CF-ACK frame ? QoS CF ACK + CF-POLL, EOSP == 1 QoS Data + CF-Ack AP SIFS SIFS QoS Data + CF-Ack Non-AP QSTA TXOP with Non AP QSTA 2 TXOP with Non AP QSTA 1 Jarkko Kneckt, Nokia

  7. Can QoS +CF-Poll frame have set EOSP bit? • What will be answer to transmitted QoS Cf-poll frame with set EOSP? • Must the QoS CF-Poll with set EOSP frame be acknowledged? QoS CF-POLL, EOSP = 1 AP Non- AP QSTA Jarkko Kneckt, Nokia

  8. QoS Data + Cf-poll • The QoS Data + CF-Poll frame handling has allows terminal acknowledgement. • However with set EOSP bit in poll frame the non AP QSTA cannot transmit any traffic. • It makes a little sense to have set EOSP in poll frame. Should it be denied? QoS Data + CF-POLL EOSP = 1 AP Non- AP QSTA QoS CF-ACK Jarkko Kneckt, Nokia

  9. QoS Cf-ACK or “plain” ack use with scheduled APSD • Pages 98 –101 define possibilities to use TXOPs and different data flows for HCCA TXOP. • The QoS CF-ACK can contain EOSP bit to terminate scheduled APSD service period. It is vital that AP can use QoS CF-ACK freely when ever ACK or CF-ACK frame is transmitted. • The CF-ACK that is used in PCF. HCCA should not use the same frame to avoid confusions. Instead of CF-ACK the QoS+CF-ACK frame should be used in HCCA. Jarkko Kneckt, Nokia

  10. Block ACK operation in HCCA streams • If block ack is used in HCCA service period, is data flow as shown in figure 62.9 or will the data flow have a frame transmission by HC and after a SIFS by non-AP QSTA? Jarkko Kneckt, Nokia

  11. Block ACK aggregation rules for HCCA • Can block ack stream be aggregated with other streams? If it can, how aggregated streams with no explicit acknowledgement and streams with block ack are handled in the same service period. • The block ack does not react on the erroneous transmissions, just marks that the receiving of the frame is failed and sets the bit field to BA appropriately, while other ACK (no explicit or normal acknowledgement) modes cannot continue the TXOP. Jarkko Kneckt, Nokia

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