Leveraging the Trade-off Between Spatial Reuse and Channel Contention in Wireless Mesh Networks -Subhrendu Chattopadhyay, Sandip Chakraborty, Sukumar Nandi Subhrendu Chattopadhyay Dept of CSE IIT Guwahati January 13, 2016 Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 1 / 24
Content Introduction 1 Motivation 2 Related Studies 3 System Model 4 Formulation of Optimization Problem 5 Proof 6 Proof: Correctness Proof 7 Proof: Correctness Proof: Convexity Solution method: Using KKT condition Distributed Heuristic Proposal 8 Simulation Results 9 10 Conclusion and Future Work Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 2 / 24
Introduction Wireless Mesh Network Internet Mesh Gate Mesh STA Client STA Figure: Wireless Mesh Architecture Multi-path communication Multi-hop communication Used as wireless backbone for providing Internet. Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. Distributed Coordination Function (DCF). CSMA/CA with binary exponential back-off algorithm. Can not provide Quality of Service (QoS) Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. Distributed Coordination Function (DCF). Point Coordination Function (PCF). Polling based mechanism. Can provide QoS Hard to implement in multi-hop scenario. Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. Distributed Coordination Function (DCF). Point Coordination Function (PCF). Mesh Coordination Function (MCF). Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. Distributed Coordination Function (DCF). Point Coordination Function (PCF). Mesh Coordination Function (MCF). Enhanced Distributed Channel Access. (EDCA) QoS by traffic priority class. No strict guarantee on QoS. MCF Controlled Channel Access. (MCCA) Spatial-TDMA (STDMA) Distributed QoS ensuring channel access mechanism. Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. MCCA working principle MCCASCANDURATION DTIM MLME−MCCAACTIVATE=true; MCCASETUP Reply ... X X X X X X MCCAOP MCCAOP Offset DURATION MCCAADVERTISEMENT MCCASETUP Request MCCAOP Periodicity Figure: MCCA Standard Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. MCCA working principle MCCAOP MCCAOP MCCAOP RESPONDER 1 Responder 2 OWNER MCCAOPADVERTISEMENT Req MCCAOPADVERTISEMENT Req MCCAADVERTISEMENT MCCAADVERTISEMENT MCCASETUP Req MCCASETUP Reply Figure: MCCA Setup procedure Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. MCCA working principle Problems of MCCA standard. Increase spatial reuse by tuning SDR parameters Non-uniform distance between transmitter- receiver pair affects flow fairness Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. MCCA working principle Problems of MCCA standard. Increase spatial reuse by tuning SDR parameters Distance between transmitter- receiver pair affects flow fairness This work tries to find a solution which ensures fairness in case of MCCA enabled Wireless Mesh Network by scheduling SDR parameters. Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Introduction Wireless Mesh Network IEEE 802.11s [1] standard for channel access. MCCA working principle Problems of MCCA standard. Increase spatial reuse by tuning SDR parameters Distance between transmitter- receiver pair affects flow fairness This work tries to find a solution which ensures fairness in case of MCCA enabled Wireless Mesh Network by scheduling SDR parameters. Scheduling of SDR parameters have known trade-off issues. Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 3 / 24
Motivation Throughput - Transmit power level dependency. G i k j k P ( t ) i k j k ≥ γ (1) G i x j k P ( t ) η + � i x j x x � = k Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Motivation Throughput - Transmit power level dependency. Throughput - Data rate dependency [2] Data rate depends on Modulation and Coding Scheme (MCS) Data Rate Receive Sensitivity 1 Mbps -101 dbm 2 Mbps -98 dbm 5.5 Mbps -92 dbm 11 Mbps -89 dbm Table: Data Sheet of Cisco Aironet 3600 Series G i k j k P ( t ) i k j k ≥ γ ( r h ) (2) G i x j k P ( t ) η + � i x j x x � = k Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Motivation Throughput - Transmit power level dependency. Throughput - Data rate dependency Trade-off between Transmit power level and Data rate D C B A F LEGENDS E P r 3 max r 2 P min r 1 P < P r < r <r max 1 2 3 min Figure: MCS and Transmit power level adjustment Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Motivation Throughput - Transmit power level dependency. Throughput - Data rate dependency Throughput - Scheduling dependency Non-conflicting flows can be scheduled simultaneously Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Motivation Throughput - Transmit power level dependency. Throughput - Data rate dependency Throughput - Scheduling dependency Throughput - Fairness dependency [3] Fair allocation of throughput Max-Min fairness Proportional fairness ( P , α )-proportionally fair 1 [4] � P log( R ) α = 1 F P ij ,α ( R ) = (3) P ij R (1 − α ) Otherwise (1 − α ) 1 log( R ) = � log ( R i ) i Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Motivation Throughput - Transmit power level dependency. Throughput - Data rate dependency Throughput - Scheduling dependency Fair allocation of throughput Max-Min fairness Proportional fairness ( P , α )-proportionally fair � P log( R ) α = 1 F P ij ,α ( R ) = (4) P ij R (1 − α ) Otherwise (1 − α ) Fair Joint Power and Rate Scheduling (Fair-JPRS) Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 4 / 24
Related Works Static Power Control Uniform Range Power Control COMPOW 1 Same power level for all nodes. Variable Range Power Control MINPOW 1 Use minimum power level to sustain communication. CLUSTERPOW 2 Clusters transmitter receiver pairs based on required transmit power level. tunneled- CLUSTERPOW 3 Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 5 / 24
Related Works Static Power Control Uniform Range Power Control COMPOW Variable Range Power Control MINPOW, CLUSTERPOW, tunneled- CLUSTERPOW Dynamic Power Control PATE - Choose least congested node PCMA,PCDC - Separate control channel POWMAC - RTS/CTS packets for power adjustment Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 5 / 24
Related Works Static Power Control Uniform Range Power Control COMPOW - Variable Range Power Control MINPOW, CLUSTERPOW, tunneled- CLUSTERPOW Dynamic Power Control PATE - Choose least congested node PCMA,PCDC - Separate control channel POWMAC - RTS/CTS packets for power adjustment Joint Design Challenge Joint Power Control and Routing Joint Power Control and Scheduling Joint Power Control, Rate Control and Scheduling Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 5 / 24
Related Studies Contd... Joint Power Control, Rate Control and Scheduling IPRS problem - Centralized optimization DPRL Algorithm - Distributed heuristic Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 6 / 24
System Model Wireless Mesh Network IEEE 802.11 b/g/n physical layer support. Software Defined Radio (SDR) supported with multiple data rate and power levels. Single interface Single channel Omni-directional Antenna Time is slotted Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 7 / 24
System Model Contd... � 1 If flow i → j uses rate h at time t X ( t ) ijh = 0 Otherwise Figure: Interpretation of X ( t ) ijh Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 8 / 24
System Model Contd... � 1 If flow i → j uses rate h at time t X ( t ) ijh = 0 Otherwise Total transmitted data per DTIM DTIM ( X ( t ) � � Tx ij = ijh × r h × σ ) t h Data rate for h = r h Slot duration σ Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 8 / 24
System Model Contd... � 1 If flow i → j uses rate h at time t X ( t ) ijh = 0 Otherwise DTIM � � ( X ( t ) Tx ij = ijh × r h × σ ) t h I ndicator variable � 1 α = 1 Γ( α ) = 0 Otherwise ( P , α ) -Proportional fairness function � � Γ( α ) log( Tx ) + (1 − Γ( α )) Tx (1 − α ) F α ( Tx ) = P ij (1 − α ) Subhrendu Chattopadhyay (IIT Guwahati) Fair-JPRS January 13, 2016 8 / 24
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