In this paper, we investigate the capacity problem of Gaussian fading multiple access relay channel with orthogonal components from the senders to the relay receiver and from the senders and relay to the receiver. This model is motivated by the practical constraint that a node cannot send and receive at the same time or in the same frequency band. We derive a capacity region for the model where...

In energy-constrained cognitive radio networks (CRNs), the choice on single channel access versus switched multichannel access is critical for energy saving and sustainable network operation. In this paper, we study and compare the energy efficiency of switched (probabilistic) multichannel access (pMCA) and fixed single-channel access (SCA) in CRNs. In pMCA, a secondary user (SU) switches chann...

Existing channel allocation methods are usually implemented for voice oriented services where the aim is to reduce the call blocking and call dropping rate. In this paper, we will investigate channel allocation schemes appropriate for data oriented services in a Broadband Fixed Wireless Access network where the aim is to reduce interference and improve overall packet throughput. A Fixed Channel...

This paper reports on MATLAB Channel Access (MCA) Toolbox – MATLAB [1] interface to EPICS Channel Access (CA) client library. We are developing the toolbox for SPEAR3 accelerator controls, but it is of general use for accelerator and experimental physics applications programming. It is packaged as a MATLAB toolbox to allow easy development of complex CA client applications entirely in MATLAB. T...

Open Spectrum systems allow fast deployment of wireless technologies by reusing under-utilized pre-allocated spectrum channels, all with minimal impact on existing primary users. However, existing proposals take a reactive sense-andavoid approach to impulsively reconfigure spectrum usage based solely on the latest observations. This can result in frequent disruptions to operations of both prima...

We propose a topology-dependent transmission scheduling algorithm that automatically schedules collision-free channel access at each node without repetitious contention phase(s) once all nodes know who are their two-hop neighbors. The bandwidth of the channel is completely devoted for data traffic, except for synchronization and occasional neighbor updates. Unique qualitative features of the pr...

We consider a wireless control architecture where multiple sensors independently and randomly access a shared wireless medium to communicate with corresponding actuators, and we develop a decentralized channel access mechanism. Each sensor iteratively adapts the rate at which it accesses the medium in order to mitigate the effect of packet collisions from simultaneously transmitting sensors on ...

In this paper, we define a two-parameter family of protocols designed for multihop packet radio networks. We call these protocols rude-CSMA because under certain circumstances, maximum throughput is obtained when nodes, even after sensing a busy channel, transmit packets anyway with a nonzero rate. The performance of these protocols is analyzed for various special and random topologies.

To support wireless-oriented services, a new generation of Web services called Mobile services (M-services) has emerged. M-services provide mobile users access to services through wireless networks. One of the important issues in M-service environment is how to discover and access M-services efficiently. In this dissertation, we propose time and power efficient access methods for M-services. We...

This paper considers the problem of power allocation between the two senders in the multiple access channel. Two power allocation criteria are developed. In particular, in the first criterion, the total available power is allocated between the two users such that the two users have the same achievable rate. In addition, the second criterion allocates the total available power such that the sum ...