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DSC leveraging uplink RTS/CTS control

Investigating performance gains and drawbacks associated with DSC, RTS/CTS control, and frame size impact in dense IEEE 802.11ax environments using NS-3 simulation.

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DSC leveraging uplink RTS/CTS control

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  1. DSC leveraging uplink RTS/CTS control Authors:

  2. Outline • Context • Simulation Environment: NS-3 • Simulation scenario and assumptions • RTS/CTS threshold setting • Impact of frame size on DSC+RTS • Conclusions • References • Appendix M. Shahwaiz Afaqui (UPC)

  3. IEEE 802.11ax enabled devices are expected to maintain and reduce energy consumed per successful information bit. • However, different amendments that are proposed to increase the efficient operation of PHY and MAC layer would work against the aforementioned requirement. • Since interference management is of paramount importance in dense deployments, IEEE 802.11ax aspires to intelligently utilize RTS/CTS method based on observed channel conditions on per node basis. • In [1], the authors highlight the possible mechanism through which an AP can control the RTS/CTS policy for the associated stations. • It has been shown in our previous presentations [2-3] that the use of DSC can increase per-user throughput in dense scenarios over the cost of increase in Frame Error Rate (FER) due to increased number of hidden nodes. • In this submission we, • investigate the performance of DSC, • By utilizing intelligent RTS/CTS control method as means to mitigate the drawbacks associated with DSC and to improve performance gains. • recommend method to select threshold to enable RTS/CTS on each node. • study the impact of frame size on RTS enabled DSC stations. 1. Context M. Shahwaiz Afaqui (UPC)

  4. NS-3 • Allows the study of protocols and network performance of large-scale systems in a controlled and scalable environment. • Main characteristics, • Discrete event simulator • Packet level simulator (layer 2 and above) • Layered architecture • Free and open source • Frequent updates ( latest version ns 3.23- release date 14-05-2015) • Large number of protocol implementations and models available, • TCP, UDP • IPV4, IPV6, static routing • IEEE 802.11 and variants, WiMAX, LTE • IEEE 802 physical layer • Mobility models and routing protocols • Ability to design indoor, outdoor or hybrid networks • etc. 2. Simulation Environment: NS-3 M. Shahwaiz Afaqui (UPC)

  5. Limitations of NS3 • Simplified abstraction of PHY layer • MPDU aggregation is not yet mature and thus not used within these simulations. • IEEE 802.11ac model has not yet been developed and current results focus on IEEE 802.11n. 2. Simulation Environment: NS-3 M. Shahwaiz Afaqui (UPC)

  6. Topology • multi-floor residential building, • 5 stories • 2×10 apartments per story. • Apartment size: 10m×10m×3m. • 1 AP placed randomly in each apartment at 1.5m height. • channelselected randomly for each cell. • Three channel scheme (1, 6, 11) 1/3 of the cells share the same channel • 5 STAs placed randomly around their respective AP. 3. Simulation scenarios and assumptions M. Shahwaiz Afaqui (UPC)

  7. Frequency band: focused on 2.4GHz , • Intended to investigate the impact of DSC in a band that is more restricted in dense environments. • Traffic: UDP CBR uplink transmission in saturation conditions is considered, • Worst case in terms of contention. • Pathloss model: Hybrid Building Propagation loss model (adapted to fit TGax channel model [3]) • We simulated specific scenarios (with same STA and AP positions) with and without DSC and RTS/CTS control method. • Additional simulation details are provided in the appendix. 3. Simulation scenarios and assumptions M. Shahwaiz Afaqui (UPC)

  8. FER of nodes used to enable and disable RTS/CTS control from the AP. • i.e. if FER of a node is greater than RTSThrehold→ enable RTS/CTS for that node. • Formula: RTSThreshold= N x AvgFER • Improvement over DSC-enabled network for longest frame (MCS0 with maximum MSDU size of 2302bytes) : 4. RTS/CTS threshold setting • ~14% improvement in throughput over DSC when RTSThrehold = 0.6 x AvgFER • N = 0.6 used in all the following experiments. M. Shahwaiz Afaqui (UPC)

  9. From previous slide, intelligent use uplink RTS/CTS control can have multifold benefits. • Tested with long frames (i.e. 1000, 1600 and 2302Bytes at MCS0) for comparative evaluation with RTS enabled DSC nodes (RTSDSC) with, • IEEE802.11n network with RTS disabled DSC nodes (NORTSDSC) • IEEE802.11n network with RTS disabled non-DSC nodes (NORTSNODSC) 5. Impact of frame size on DSC+RTS (1/2) • Up to 55% improvement in throughput (longest frame duration). • RTS control adds to benefits of DSC. • Maximum FER improvements are achieved for small frame size. M. Shahwaiz Afaqui (UPC)

  10. Tested with shorter frames (2302Bytes at MCS7) for comparative evaluation with RTS enabled DSC nodes (RTSDSC) with, • IEEE802.11n network with RTS disabled DSC nodes (NORTSDSC) • IEEE802.11n network with RTS disabled non-DSC nodes (NORTSNODSC) 5. Impact of frame size on DSC+RTS (2/2) • For short frames, RTS/CTS not paying off (in terms of throughput). • Better off DSC on its own. M. Shahwaiz Afaqui (UPC)

  11. More efficient DSC is achieved when combined with uplink RTS/CTS control, as proposed in [1]. • One of the major drawbacks of DSC scheme was the increase in FER due to hidden nodes  RTS enabled DSC network can mitigate the aforementioned problem. • We propose to intelligently enable RTS/CTS, • The AP knows uplink FER of all associated STAs • AP decides which STA uses RTS/CTS based on: • Threshold FER derived from average FER (RTSThreshold = 1.4 x AvgFER for long frames) • Frame size (excessive overhead for small packets) 6. Conclusions M. Shahwaiz Afaqui (UPC)

  12. [1] Sigurd Schelstraete, IEEE 802.11-15-0059, Uplink RTS/CTS Control. [2] M. Shahwaiz Afaqui , IEEE 802.11-15-0027, Simulation-based evaluation of DSC in residential scenario. [3] M. Shahwaiz Afaqui, IEEE 802.11-15-0371, Proposal and simulation based evaluation of DSC-AP Algorithm [4] Jianhan Liu et al., IEEE 802.11-14-0882r4, TGax Channel Model Document 7. References M. Shahwaiz Afaqui (UPC)

  13. PHY parameters Simulation assumptions M. Shahwaiz Afaqui (UPC)

  14. MAC parameters • Simulation parameters M. Shahwaiz Afaqui (UPC)

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