Mingyuan Yan, Shouling Ji, Meng Han, Yingshu Li, and Zhipeng Cai

Transcription

1 Mingyuan Yan, Shouling Ji, Meng Han, Yingshu Li, and Zhipeng Cai Department of Computer Science, Georgia State University, ATL, USA School of Electrical and Computer Engineering, Georgia Institute of Technology, ATL, USA

2 Introduction System model and problem formulation Scheduling algorithm for MLDAS-CR Performance evaluation Conclusion

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4 CRNs a promising solution to alleviate the spectrum shortage and underutilization problem However, the spectrum availability is quite limited for unlicensed users unlicensed users need to avoid collisions with the ongoing transmissions between both licensed users and other unlicensed users, unlicensed users can only access the licensed spectrum opportunistically This uncertainty constrains the usage of CRNs on heavy transmission and time sensitive applications

5 Data aggregation an efficient strategy to alleviate energy consumption and medium access contention During the data aggregation process, raw readings are aggregated and then transferred in the network. plays an vital role in the summarized data gathering procedure A large amount of research on data aggregation in wireless network can be found in existing literatures None of them considering cognitive radio capability

6 Existing literature A large amount of effort has been dedicated to the investigation of CRNs and data aggregation in wireless networks introducing cognitive radio capability to improve the performance of wireless networks[1]-[4] rarely concentrate on how to use cognitive radio technique to promote the performance of data aggregation in conventional wireless networks

7 Data aggregation in wireless networks with cognitive radio capability users in the network are equipped with cognitive radios As in conventional wireless networks, an unlicensed spectrum is assigned to the network. It is available to the in-network users all the time. Meanwhile, the cognitive radio enables wireless users searching and exploiting the spectrum holes alleviate contention on the default spectrum and speed up the transmission Procedure regular data transmission can still be processed if there is no spectrum hole when extra idle spectrum exists, some users can move to that spectrum

8 Data aggregation scheduling in wireless networks with cognitive radio capability instead of taking unoccupied spectrum holes as our only hope for data transmission, we consider them as our assistant and use them to accelerate the data aggregation process Formalize the problem Scheduling algorithm for MLDAS-CR Scheduling Algorithm Based on LP Scheduling with Expected Delay Guarantee Performance evaluation based on simulations

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10 Auxiliary Network (AN) m randomly deployed Auxiliary Users (AUs) denoted by set U a = {U 1,U 2,,U m } Spectrums S a Transmission radius T a Interference radius I a AU is either active or inactive in a time slot active senders follow a two-dimensional Poisson point process XS with density λ Active receiver forms another two-dimensional Poisson point process XR with the same density

11 Wireless network Dense with n randomly deployed users n users U r = {u 1,u 2,,u n } Each SU is equipped with a single, half-duplex cognitive radio u b U r r wants to get the aggregated information from the network Transmission radius T r Interference radius I r Default working spectrum S r Unit Disk Graph Interference Model T a = I a and T r = I r

12 Exterior collision Interior collision

13 Minimum Latency Data Aggregation Scheduling in a wireless network with Cognitive Radio (MLDAS-CR)

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15 2-norm CDS-based Balanced routing tree

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18 ILP LP solve Optimal solution for LP rounding Feasible solution for ILP Scheduling Not done? Yes End

19 CDS-based balanced routing tree Schedule white nodes first using first-fit strategy and then schedule black and gray nodes alternatively

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25 Conclusion investigate the Minimum Latency Data Aggregation Scheduling in wireless networks with Cognitive Radio capability (MLDAS-CR) problem A scheduling algorithm based on Integer Linear Programming (ILP) and Linear Programming (LP) is proposed An efficient algorithm based on a balanced routing tree is presented Theoretical analysis shows that the later proposed algorithm has a guaranteed latency bound. The simulation results verify the performance of the proposed solutions.

26 Mingyuan Yan, Shouling Ji, Meng Han, Yingshu Li, and Zhipeng Cai Department of Computer Science, Georgia State University, ATL, USA School of Electrical and Computer Engineering, Georgia Institute of Technology, ATL, USA