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DL efficiency enhancement in high dense network

DL efficiency enhancement in high dense network. Authors:. Date: 2013-11-10. Abstract. This contribution introduces an approach for enhancing DL efficiency in dense WLAN environment. Motivation.

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DL efficiency enhancement in high dense network

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  1. DL efficiency enhancement in high dense network Authors: Date: 2013-11-10 Jeongki Kim, LG Electronics

  2. Abstract • This contribution introduces an approach for enhancing DL efficiency in dense WLAN environment. Jeongki Kim, LG Electronics

  3. Motivation • DL efficiency issignificantly getting worse in high dense networks due to the following reasons • There are more buffered data in AP in high dense STA network • Also, AP’s DL TX opportunities becomes smaller due to the contention with many STAs [2][3] • TX opportunity of AP = 1/(N+1) (N: No. of non-AP STAs within a BSS) • Increased collision makes the doubled contention window [2][3] • TX delay becomes longer due to large CW • Smaller TX opportunity and longer TX delay, more buffered data • The buffer can be overflown in case of severe high dense environment • Some buffered data may be discarded • Repeated vicious circle degrades the DL throughput rapidly • HEW needs to enhance DL efficiency in dense network by prioritizing DL traffic Jeongki Kim, LG Electronics

  4. Possible approaches • Possible methods for enhancing the DL throughput in dense networks • Option 1: Giving higher TX priority to AP (e.g., small IFS, small CW) • May increase the collision • Unfairness with STAs and increasing the number of pending STAs • Option 2: Time-dedicated DL access (e.g., In the Beacon) • DL dedicated interval can increase the UL access delay of STAs • To avoid the problems in the above, this contribution suggests a frequency-dedicated DL access Jeongki Kim, LG Electronics

  5. DL oriented channel design • DL oriented channel: The channel on which DL frames are sent to associated STAs and on which UL data is not sent • Link setup procedures (e.g., authentication, association) can be performed on the normal channel Jeongki Kim, LG Electronics

  6. Further discussion points • Which frames can be sent on the DL oriented channel? • Stand-alone DL frame (e.g., DL data, DL control/management frame like RTS) • DL-dependant UL frame (e.g., ACK for DL frame , CTS for DL RTS) • Others? • DL frame TX method on DL oriented channel • Legacy methods(e.g., DCF, PCF, EDCA, HCF, etc.) • Or need new methods? • Issues in overlapping BSSs • Coexistence with legacy primary/secondary channel of neighbor BSS • DL oriented channels of OBSSs are same channels or Different? • Others? Jeongki Kim, LG Electronics

  7. Conclusion • DL throughput is degraded drastically in dense WLAN environment • Because AP sends the DL data with the same priority as many non-AP STAs with its BSS • One method to increase the DL efficiency is to reduce the level of contention with non-AP STAs • We propose the concept of DL oriented channel as a candidate technology of HEW to minimize the contention with non-AP STAs when AP sends DL data to STAs Jeongki Kim, LG Electronics

  8. References • [1] IEEE 802.11-13/0657r6 Usage models and requirements for IEEE 802.11 High Efficiency WLAN study group (HEW SG) • [2] Marcelo M. Carvalho and J. J. Garcia-Luna-Aceves, Delay Analysis of IEEE 802.11 in Single-Hop Networks, In Proceedings of the 11th IEEE International Conference on Network Protocols, 2003. • [3]Byeong Gi Lee and Sunghyun Choi, Broadband wireless access and local networks: Mobile WiMAX and WiFi, Artec House, 2008 Jeongki Kim, LG Electronics

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