Myunghwan Seo

Dynamic frequency hopping channel management in cognitive radio ad-hoc networks

In this paper we propose a novel out-of-band spectrum sensing and dynamic channel management scheme for frequency hopping-based cognitive radio ad-hoc networks. At the beginning of each channel hopping time, member nodes perform spectrum sensing of the next hopping channel. Based on the proposed collision free primary detection notification, the member nodes determine whether they execute a hopping time extension of the current channel or not. When the primary detected hopping channel is re-idled, the hopping pattern recovery procedure is performed. In this paper we evaluate the performance of the proposed dynamic sensing and hopping channel extension mechanism for the various wireless network conditions. As a result, the proposed method can increase channel utilization and provide reliable channel management operation.

Genetic algorithm based sensing and channel allocation in cognitive ad-hoc networks

We present a novel out-of-band spectrum sensing and channel allocation scheme for frequency hopping based cognitive radio networks using genetic algorithm. Based on the optimized solution derived from GA, a set of nodes for sensing the next hopping channel and a set of nodes for transmitting data on current channel are derived. The channel allocation is performed according to individual traffic demand of each node. Simulation results show that the proposed scheme can achieve reliable spectrum sensing and efficient channel allocation.

Initial rendezvous protocol using multicarrier operation for ad-hoc cognitive radio networks

In cognitive radio technology, the overall capacity of communications systems can be improved without allocating additional bands by allowing secondary system to utilize the licensed band when a primary system who has right to use the band does not use it. In this paper, we consider how to set up a common channel for data communication in an ad-hoc networks consisting of a cluster head and member nodes using a cognitive radio technology. We propose a new initial rendezvous protocol that uses the system activation signal which has angle difference patterns with multicarrier operations.

Common channel initialization protocol in cognitive radio ad-hoc networks

Due to the increasing demand for spectrum resources, cognitive radio network and dynamic spectrum access get a lot of attention for efficiently utilizing the limited spectrum resources. To set up cluster-based CR ad-hoc common channels, conventional methods require relatively long time to successfully exchange the initialization messages. In this paper, we propose a fast and reliable common channel initialization protocol for CR ad-hoc networks. In the proposed method, cluster head sequentially broadcasts a system activation signal through its available channels with a predetermined correlation pattern. To detect the cluster heads broadcasting channels and to join the cluster, each member node takes FFT and computes autocorrelation of FFT bin sequence for each available channel of the member node. The join request and channel decision procedure are also presented in this paper. In the simulation study, the performance of the proposed method is evaluated.

Dynamic Channel Selection with Snooping for Multi-Channel Multi-Hop Wireless Networks

The dynamic channel selection mechanism used in existing multi-channel MAC protocols selects an idle data channel based on channel usage information from one-hop neighbor nodes. However, this method can cause multi-channel hidden node problem in multi-hop wireless networks. This letter proposes a new approach to channel selection. Nodes snoop data channels during idle times and then select an idle data channel within the carrier sensing range using both the snooping results and the channel usage information. Our simulation results verify that the proposed channel selection approach can effectively avoid the multi-channel hidden node problem and improve the networkwide performance.