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Ad hoc on-demand distance vector (AODV) routing protocol has been investigated for mobile ad hoc networks and more commonly used. However, if there are unidirectional links in the networks, significantly long latency may be required for a route establishment when AODV routing protocol is used. We assume that unidirectional links can be occurred due to a difference of transmission power between the...
Wide area ubiquitous networks should have the capability to handle more than 10,000 wireless terminals in a large wireless cell with the radius of several kilometers. However, the functions of wireless terminal are severely limited due to low power consumption and low cost requirements. Therefore, there is a need for a sophisticated wireless access system that employs smart wireless signal processing...
Recently, wireless ad hoc communication systems have been receiving attention. In order to improve the efficiency of such networks, researchers have tried to apply adaptive array antennas (AAA) for interference cancellation in the space domain. In this paper, we propose a new method based on a new concept, called cross-degree of freedom (CDOF), for the application of AAA to ad hoc communications....
Wireless ad hoc networks attract interests of researchers. In such networks, data packets are relayed by nodes from a source node to a destination node. This is referred to as multi-hop communication. For such system, it is known that the IEEE802.11 DCF is not efficient. Then, in order to improve the efficiency, several methods were proposed conventionally. However, most of them are not aware of realistic...
In this paper, we propose a soft decision based cooperative sensing method for cognitive radio (CR) in ad-hoc networks. A CR can sense a surrounding radio environment and adapt to the environment by the reconfigurability to achieve more effective frequency utilization. Observing the environment, CR should detect presence or absence of primary user and exploits this information to opportunistically...
This paper presents a novel iterative channel exchange algorithm to enhance a previous resource allocation. The objective is the improvement of network throughput in wireless ad-hoc networks by channel exchanges among neighbor nodes. The algorithm makes use of knowledge of channel status and usage, and can be implemented in a distributed manner. Due to the iterative approach, stepwise improvement...
This paper proposes a MAC protocol for efficient broadcasting in ad hoc networks. Since pure flooding leads to serious redundant rebroadcasts, packet contention and packet collision, known as the broadcast storm problem, this paper focuses on how to reduce redundant rebroadcasts. Several broadcast protocols periodically exchange hello packets to predetermine effective sets of rebroadcasting nodes,...
The cognitive radio is a secondary wireless communication system that can overlap the frequency band assigned to the primary system by recognizing the frequency status. Ad-hoc cognitive radio is considered for realizing the cognitive radio by using multi-hop communication networks without giving the large interference toward the primary system. We have proposed the STBC distributed ARQ system applied...
In this paper, we propose a new concept namely forward interference avoidance (FIA) using adaptive array antennas (AAAs) for wireless mobile ad hoc networks (MANETs). It enables nodes to avoid interfering with other nodes so that it results in increasing the number of co-existent wireless links. The performance improvement of MANET in terms of the increase of the number of co-existent communication...
In this paper, we focus on the cognitive radio, which reconfigures the radio transceiver according to the surrounding radio environment. We introduce a development to an ad-hoc cognitive radio that can realize a frequency sharing system under existing communication systems using a multi-hop small power communication. Here, we discuss the surrounding radio environment recognition methods in the distributed...
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