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DSC leveraging uplink RTS/CTS control. Authors:. Outline. Context Simulation Environment: NS-3 Simulation scenario and assumptions RTS/CTS threshold setting Impact of frame size on DSC+RTS Conclusions References Appendix.
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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)
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)
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)
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)
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)
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)
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)
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)
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)
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)
[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)
PHY parameters Simulation assumptions M. Shahwaiz Afaqui (UPC)
MAC parameters • Simulation parameters M. Shahwaiz Afaqui (UPC)