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Agile spectrum evacuation in cognitive radio networks

- Shahid, Mohammad, Kamruzzaman, Joarder

  • Authors: Shahid, Mohammad , Kamruzzaman, Joarder
  • Date: 2010
  • Type: Text , Conference paper
  • Relation: 2010 IEEE International Conference on Communications p. 1-6
  • Full Text: false
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  • Description: One of the most important aspects of cognitive radio technology is to avoid interference on the primary system. Typically, the interference is avoided by sensing a particular spectrum band for the existence of primary transmitter while all secondary users are kept quiet. Hence, a periodic sensing method is used which incorporates alternate phases of sensing and transmission by all secondary users. In this paper, we introduce a new method of agile spectrum evacuation that allows any secondary user to continue using the band until the return of the primary user is detected through the formation of a set of users that exclusively engages in sensing primary user in a cooperative manner. The proposed method yields better interference protection and enhanced spectrum utilization.

VoIP service over multihop 802.11 networks with power capture and channel noise

- Siddique, Md, Kamruzzaman, Joarder

  • Authors: Siddique, Md , Kamruzzaman, Joarder
  • Date: 2010
  • Type: Text , Conference paper
  • Relation: 2010 IEEE International Conference on Communications p. 1-6
  • Full Text: false
  • Reviewed:
  • Description: The quick market growth and ubiquitous acceptance of VoIP are primarily due to cheap service. VoIP services can be availed in mobile devices at a very low cost by employing IEEE 802.11 to provide last mile coverage. But call capacity is very low in these networks and call jitter occurs if voice quality requirements are not precisely met. We present a VoIP call capacity model for 802.11 networks which considers the most important real world factors like power capture and imperfect channel. Incorporating multiple channels can increase call capacity while multihop network can provide considerably large coverage. Our capacity model incorporates the effects of both multiple channels and multihop networks. We also consider the availability of multiple radio interfaces and conference call scenarios for ubiquitous applications of our model. To ensure voice quality, in addition to contention analysis, we also model the queue considering collision domain at each hop and formulate call capacity by estimating precise impairment budget over multihop.
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