||SMC-MAC: An Efficient Stepwise Multi-channel MAC Protocol for Ad Hoc Networks
||Department of Computer Science and Information Engineering
Hidden Terminal Problem
||近年來，發展多頻道媒體存取協定已受到極大的關注與討論，並被認為是開發頻寬利用率的有效方法。在發展多頻道通訊協定時所遭遇最大的挑戰便是主機會面問題(Rendezvous Problem)與多頻道隱藏節點問題(Multi-Channel Hidden Terminal Problem)。為解決會面問題，有些研究的作法是讓所有主機在一共同會面的窄頻，以便進一步協調資料傳輸該使用的頻道。然而，此種作法將可能產生多頻道隱藏主機節點問題。另外，也有一些研究的作法，是讓所有主機週期性地在特定頻道的ATIM Window共同聚集，以安排資料交換的頻道，但這樣的作法會造成其它頻道ATIM Window的頻寬利用率降低。本篇論文提出一多頻道MAC協定(SMC-MAC)，以階梯式的頻道模型，利用單一天線便可解決多頻道的主機會面與多頻道隱藏主機節點問題，並節省頻寬資源浪費。
||Multi-channel MAC protocols have recently attracted significant attention in wireless networking research because they have potential to exploit frequency resources for increasing the overall throughput of wireless Ad-Hoc networks. The most common challenge for developing the multi-channel MAC protocols is the well-known rendezvous problem. In literature, some studies assumed that each device equips one additional antenna, staying on the control channel for negotiating the channel for data exchange. However, the hardware cost has been increased. Some other works ask all devices staying on a predefined channel in ATIM window for negotiating the channel for data exchange. However, the bandwidth utilization is low since all channels other than the predefined channel are not used in the ATIM window. This thesis presents an Efficient Stepwise Multi-channel MAC Protocol, called SMC-MAC, for the Ad Hoc Network. The proposed SMC-MAC is developed based upon single antenna and applies stepwise channel model to exploit the multi-channel bandwidth resource.
1. Introduction 1
2. Related Work 5
3. System Model and Problem Statement 9
3.1 SYSTEM MODEL 9
3.2 PROBLEM STATEMENT 10
4. Design of SMC-MAC Protocol 14
4.1 THE STEPWISE CHANNEL MODEL 14
4.2 RENDEZVOUS IN STEPWISE CHANNEL MODEL 16
4.3 CONTROL PERIOD DESIGN 17
4.4 DATA PERIOD DESIGN 27
5. Advanced Design of SMC-MAC Protocol 29
5.1 CHANNEL UTILIZATION ENHANCEMENT POLICY 29
5.2 MULTICASTING SUPPORT POLICY 32
6. Performance Evaluation 35
6.1 SIMULATION ENVIRONMENT 35
6.2 SIMULATION RESULTS 36
7. Conclusions 48
Figure 1. Stepwise channel model. 14
Figure 2. Negotiation slots and data slots. 16
Figure 3. Receiver declaration packet. 21
Figure 4. Available slots operation. 26
Figure 5. Negotiation of transmission pair. 26
Figure 6. Channel switching during data period. 28
Figure 7. Network throughput comparison by varying the ratio of control and data periods and the offered traffics. 37
Figure 8. Packet collision comparison with different traffics. 38
Figure 9. Packet delay comparison with different offered traffics. 39
Figure 10. Packet delay comparison with different ratio of offered traffic distribution. 40
Figure 11. Fairness index at varying offered traffic. 43
Figure 12. Fairness index at different traffic ratio. 44
Figure 13. Data slot idle rate by varying offered traffics. 45
Figure 14. Network throughput by varying the number of multicast groups and the number of their members. 46
Figure 15. Average packet delay time of multicast service comparison by varying the number of multicast groups and multicast members. 47
Table 1. Simulation settings 36
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