Post on 22-Feb-2016
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Physical Layer Network Coding with Signal Alignment
Ruiting Zhou+, Zongpeng Li+, Chuan Wu*, Carey Williamson+
+University of Calgary*University of Hong Kong
Ruiting Zhou Univerisity of Calgary
Outline• 1. Introduction• 2. PNC-SA Scheme• 3. Precoding Design and BER Analysis• 4. General Applications of PNC-SA and
Throughput• 5. Conclusion
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1. Introduction• MIMO: Multi-input multi-output• Throughput is limited by the number of
antennas per AP
Figure 1: MIMO LANs
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1. Introduction• Second client-AP pair, transmit >2
packets? No!• Interference Alignment and Cancellation
(IAC) breaks through this bottleneck• IAC allows 3 concurrent packets Transmitters can control the alignment of their
signals at a receiver APs are typically connected to a backend Ethernet
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1. Introduction• IAC treats the second and third packets as
one unknown• AP1 sends on the Ethernet to AP21p
Figure 2: IAC example
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2. PNC-SA Scheme• Introduction to Digital Network Coding• Physical-Layer Network Coding• Physical layer Network Coding with
Signal Alignment Scheme
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2. PNC-SA Scheme• Traditional Transmission Scheduling: 4
time slots.
• Digital Network Coding: 3 time slots It is applied on digital bits that have been
correctly received:
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2. PNC-SA Scheme• Physical-Layer Network Coding (PNC): 2 time slots Additions of the EM signals are mapped to
additions of digital bit streams
BPSK maps from{-1, 1} to {0, 1} PNC demodulation maps from {+2, 0, -2} to {0,
1}
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2. PNC-SA Scheme• Physical layer Network Coding with
Signal Alignment (PNC-SA)• Align simultaneous transmissions from
multiple MIMO senders.
Figure 3: PNC-SA
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3. Precoding and BER Analysis
• Precoding — Alignment constraint:
• Solution:
Figure 3: PNC-SA
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3. Precoding and BER Analysis
• Comparison of the BER performance of
PNC-SA and IAC
Figure 4: BER performance
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4. Applications and Throughput• General applications of PNC-SA and
their throughput: PNC-SA for Info Exchange PNC-SA for Multi-Sender Multicast
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4. Applications and Throughput• PNC-SA for Info Exchange: Alice-and-
Bob communication
Figure 5: PNC-SA with three antennas per node
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4. Applications and Throughput• PNC-SA for Info Exchange PNC-SA: 6 packets in 2 time slots Digital network coding: 3 time slots, No coding:
4 time slots
Figure 6: Packet-level throughput for information exchange
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4. Applications and Throughput• PNC-SA for Multi-Sender Multicast PNC-SA: 6 packets in 4 time slots
Figure 7: Multicast from top layer to bottom layer
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4. Applications and Throughput• Digital network coding: 5 time slots• Straightforward multicast scheme without
coding: 7 time slots
Figure 8: Packet-level throughput for multicast
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5. Conclusion
• PNC-SA, SA coupled with PNC, can open new design spaces for routing in MIMO wireless networks
• Study the optimal precoding and BER performance
• Demonstrate the general applications
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• Thanks!
• Questions?
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