An Experimental Evaluation of Selective Cooperative Relaying for - - PowerPoint PPT Presentation
An Experimental Evaluation of Selective Cooperative Relaying for Industrial Wireless Sensor Networks Nikolaj Marchenko, Torsten Andre, G unter Brandner, Wasif Masood, and Christian Bettstetter Institute of Networked and Embedded Systems
Institute of Networked and Embedded Systems University of Klagenfurt, Austria
S R D
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◮ Lots of theoretical work on cooperative relaying ◮ Some experimental studies (40+ articles): 1 Software-Defined Radios: Mostly PHY Layer, few nodes 2 Wireless Sensor Nodes: MAC/Network layer, many nodes
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◮ Monitoring and control of production processes ◮ Harsh environment for wireless signal propagation ◮ Very strict requirements on link reliability and delay ◮ Standards: WirelessHART, ISA100.11a, Zigbee IA Profile
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1 Which metrics to use for relay selection?
◮ Channel quality info, residual battery life, etc.
2 How selection is coordindated?
◮ Signaling messages, contention mechanism, etc.
3 How often a relay is updated?
◮ Update requirements and policy.
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◮ random contention of candidates in window w. ◮ based on current Link Quality Indicators S − R and R − D.
S Ri D DATA (mc) ACK (mc) TACK DATA ACK
err
DATA (mc) ACK (mc) ACK TACK
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◮ A new relay selection when in a window Wa more than εa
◮ Selection and retransmission procedure same as periodic
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1 have received the packet correctly 2 have a good channel to the destination
S Ri D DATA (bc) ACK (mc) TACK DATA ACK
err
S_RREQ (bc)
D_RSEL R_CAND
relay selection
rand(0,w)
S_RREQ (bc) rand(0,w)
err no err ACK err
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◮ Crossbow TelosB ◮ TinyOS implementation ◮ Transmission: 2.4 GHz, 256 kbit/s, TxPower: -4 dBm
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◮ 7 nodes, 6 tested links
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60m 25m
◮ Two kind of experiments: 1 Trace-based analysis on individual link:
2 Explicit experimental comparison over all links
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1 Periodic selection: every 200 packets 2 Adaptive selection: if error rate > 10% for last 50 packets.
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selection period, data packets delivery ratio 1 2 3 5 100 101 102 0.7 0.75 0.8 0.85 0.9 0.95 selection period in pkts number of selection per 100 data pkts 1 2 3 4 5 # relays 100 101 102 10−1 100 101 102
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window size, Wa delivery ratio N = 3, 4, 5 N = 2 N = 1 50 100 150 200 250 300 0.7 0.75 0.8 0.85 0.9 window size, Wa selections per 100 data packets 1 2 3 4 5 50 100 150 200 250 300 10−1 100 101 102
error rate threshold, εa total delivery ratio 1 2 3 5 0.2 0.4 0.6 0.8 1 0.7 0.75 0.8 0.85 0.9 error rate threshold, εa selections per 100 data packets 1 2 3 5 0.2 0.4 0.6 0.8 1 10−3 10−2 10−1 100 101 102
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periodic adaptive reactive time 160ms 160ms 160ms time div. time div. 160ms
Sample # Delivery ratio per sample Exp.2. Test:3081 direct periodic adaptive reactive 500 1000 1500 2000 0.8 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 16/21
◮ Measurements on 3 days, each 12 hours. ◮ Total 810K DATA packets sent by source nodes ◮ 33K on each link and each scheme, over 6 hours time. ◮ Periodic selection: Tsel = 400 · 160 ms = 64sec ◮ Adaptive selection: Wa = 100, εa = 0.1
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delivery ratio in a sample cdf single direct transmission time diversity periodic adaptive reactive 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10−3 10−2 10−1 100
time diversity periodic delivery ratio by a single direct transmission in a sample total delivery ratio adaptive reactive 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 18/21
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1 Cooperative relaying provides up to 99% delivery ratio 2 Short-term outages are also avoided 3 Adaptive selection provides best tradeoff between delivery
◮ N. Marchenko, et al.
◮ T. Andre, et al. WiNMee Workshop, May 2013. ◮ T. Andre, et al. GLOBECOM’12.
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