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This paper presents .mZig, a novel design for enabling multi-packet reception in ZigBee networks. It discusses the motivation, preliminary design, implementation, and performance evaluation of .mZig. The paper also covers related works, collision problems, and techniques for resolving multi-packet collisions. The performance of .mZig is evaluated in terms of bit error rate, throughput, and static vs mobile scenarios.
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1 2 3 5 4 Table of Contents Motivation Preliminary Design Implementation Performance Evaluation
1 2 3 5 4 Table of Contents Motivation
1 ZigBee Communication 2 • Standard: IEEE 802.15.4 • Focus: low-power, low-cost, low-bitrate • Applications: Sensor networks; Smart homes; Internet of things; Industrial control; ...... 3 4 5
1 Concurrent Transmissions in ZigBee 2 Cluster topology Tree topology 3 4 5
Collision 1 Collision Problem 2 3 4 5
1 Related Work 2 3 4 5
1 Our Goal 2 • No pre-known info • No retransmission requirement • Multiple TXs are allowed to send different packets 3 4 Decompose multiple packets from one collision directly! 5
1 2 3 5 4 Table of Contents Preliminary
1 ZigBee Specification 2 3 4 5
1 Baseband Signal at TX side 2 3 4 5
1 Features of Chips at RX side 2 • Oversampling: sampling rate of recent ADCs is much higher than 2MHz. • Known shaping: half-sine. • Uniform amplitude: O-QPSK, no ASK or QAM. 3 4 How to use these features to resolve multi-packet collisions? 5
1 2 3 5 4 Table of Contents Design
1 Core Design of mZig 2 • Example: a two-packet collision. • Alice: 11000; Bob: 10100. • Every chip has 5 samples. 3 4 5
1 Two Categories of Collisions 2 • with chip-level time offset (w/ CTO) • without chip-level time offset (w/o CTO) 3 4 5
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5
Collision-free samples 1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Step I: Extract collision-free samples
Estimated samples 1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Step II: Estimate samples to form a whole chip
New collision-free samples 1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Substract the estimated chip from the collision
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Repeat the extraction and estimation steps
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Repeat the extraction and estimation steps
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Repeat the extraction and estimation steps
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Repeat the extraction and estimation steps
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Repeat the extraction and estimation steps
1 CrossIC 2 • CrossInterference Cancellation (CrossIC) for collision w/ CTO. 3 4 5 Repeat the extraction and estimation steps
1 AmpCoD 2 • Amplitude Combination based Decomposition (AmpCoD) for collision w/o CTO. 3 4 5
1 AmpCoD 2 • Amplitude Combination based Decomposition (AmpCoD) for collision w/o CTO. 3 4 5
1 2 3 4 5
1 2 3 5 4 Table of Contents Implementation
1 RX PHY: ZigBee v.s. mZig 2 3 4 5
1 DmZig Module 2 3 4 5
1 Testbed 2 • RX: USRP X310 + PC • TX: USRP B210*6 + Laptop*6 + iRobots*6 3 4 5
1 2 3 5 4 Table of Contents Performance Evaluation
1 Experiment Setting 2 3 4 5
Reference 1 BER: Different Sampling Rates 2 3 4 5
Reference 1 BER: Different Techniques 2 3 4 5
1 Throughput: Different Techniques 2 3 4 5
1 Throughput: Different Techniques 2 3 4 5
1X 4.5X 1 Throughput: Different Techniques 2 3 4 5
1 Throughput: Static v.s. Mobile 2 3 4 5
1 Conclusion 2 • We design mZig, a novel RX design to enable multi-packet reception in ZigBee. Theoritcally, the maximal concurrent transmissions is m=S/2C. • We implement mZig on USRPs. In our testbed, the throughput of mZig achieves 4.5x of ZigBee with four or more TXs. 3 4 5
Q & A linghe.kong@mail.mcgill.ca 44
Anti-Noise Design • For CrossIC • For AmpCoD
Multipath Filter • Channel estimation is required to estimate the impulse responses of multipath. • Multipath effect is filtered chip-by-chip.
Frequency Offset Compensation • Channel estimation is also required to estimate the frequency offset. • Compensate the frequency offset chip-by-chip.