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Buddy Routing: A Routing Paradigm for NanoNets Based on Physical Layer Network Coding. Ruiting Zhou+, Zongpeng Li+, Chuan Wu*, Carey Williamson+ + University of Calgary *University of Hong Kong. Outline. 1. Introduction to NanoNets 2. Enabling Buddy Routing
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Buddy Routing: A Routing Paradigm for NanoNets Based on Physical Layer Network Coding RuitingZhou+, Zongpeng Li+, Chuan Wu*, Carey Williamson+ +University of Calgary *University of Hong Kong
Outline • 1. Introduction to NanoNets • 2. Enabling Buddy Routing • 3. Theoretical Analysis • 4. Buddy Routing: Unicast • 5. Buddy Routing: Multicast • 6. Conclusion
1. Introduction to NanoNets • NanoNets • Collaborative Data Forwarding
1.1 NanoNets • NanoNets:Networks of nanomachines at extremely small dimensions -- on the order of nanometers or micrometers. • Basic computing and communication feasible on nanonodes. • Large network size and node density, low cost and available power.
1.2 Collaborative Data Forwarding • Group nanonodes into collaborating pairs: overcome power constraint, enhance the communication range and rate. • Enabled by physical layer network coding (PNC).
1.2 Collaborative Data Forwarding • Enabled by Amplify&Forward (A&F). • Intra-pair transmission: transmit an amplified version of the received analog signal:
2. Enabling Buddy Routing • PNC vs A&F: Multi-hop Transmission • PNC vs A&F: One-hop BER
2.1 PNC vs A&F: Multi-hop Transmission • PNC: Except at the source pair, no need for half-packet sharing. • A&F:Intra-pair sharing of a half-packet is required at each hop, an extra step of transmission. • lower end-to-end data throughput.
2.2 PNC vs A&F: One-hop BER • BER of PNC is almost the same as, but slightly worse than, that of A&F, under the same SNR at the receiver side.
3. Theoretical Analysis • System Model and Parameters • Capacity and Power Consumption
3.1 System Model and Parameters • MAC layer protocol: TDMA • Two types of time slots: • Long time slot : long-hop data transmission happen simultaneously every three hops • Short time slot: all the intra-pair short hops transmit simultaneously
3.2 Capacity and Power Consumption • We analyzed the end-to-end routing capacity of a BR route at very high SNR with and without noise considered. • The extra power consumption overhead caused by BR is below 20%. • The capacity is increased by a factor of 2.
4. Buddy Routing: Unicast • BR Unicast Routing Algorithm • Simulation
4.1 BR Unicast Algorithm • Step 1: Pair-to-pair greedy geographic unicast routing. • Forwarding process: it looks for a next-hop pair between the two co-axial circles of radius and , which is closest to the destination. • If the last pair is too close to the destination, replaced by a new pair such that the distance between the new pair and the destination is just larger than . • and are the minimum and maximum allowed distances between two neighbor buddy pairs.
4.1 BR UnicastAlgorithm • Radius of red circle is the maximum distance between a pair of buddy nodes. • When Pair 70 looks for the next hop towards the destination, it can only search the area in the blue ring.
4.1 BR UnicastAlgorithm • Step 2: Iterative MAC layer optimization. • Adjust time slot: so that the capacity in each time slot is equal. • Inter-pair power optimization: adjust the long hop transmission power — achieve equal capacity at bottleneck link & 2 neighbor links. • Intra-pair power optimization: adjust the short hop transmission power —achieve equal capacity at bottleneck pair & 2 neighbor pairs.
4.1 BR Unicast Algorithm • End-to-end throughput is doubled after the iterative power/MAC optimization
4.2 Simulation • BR Unicast, end-to-end throughput comparison, different x-axis. • Throughput of BR after optimization is almost twice that of point-to-point routing
5. Buddy Routing: Multicast • The Multicast BR Gadget • BR Multicast Tree
5.1 The Multicast BR Gadget • Multicast: has branches in the transmission topology. • Replicate a data packet from an upstream node pair to two pairs.
5.2 BR Multicast Tree • One-to-four multicast
6. Conclusion • We proposed a new PNC-based routing paradigm, Buddy Routing, for NanoNets. • BR has a potential to break through the nodal power limit in NanoNets. • It can substantially improve the unicast and multicast throughput, as verified by our theoretical analysis and simulation results
Thanks! • Questions?