Effects of relay position and power allocation in space-time coded cooperative wireless systems

n/

Cooperative UWB-Based Positioning Systems: CDAP Algorithm and Experimental Results

The need for accurate positioning has attracted significant interest in recent years, especially in cluttered environments where signals from satellite navigation systems are not reliable. Positioning systems based on ultrawide bandwidth (UWB) technology have been considered due to the property of UWB signals to resolve multipath and penetrate obstacles. However, range-based localization techniques typically lack accuracy in dense cluttered environments, due to line-of-sight blockage and excess propagation delay through material. In this paper, we consider positioning in a real indoor environment scenario, where anchor nodes are deployed in known locations, and one or more target nodes wish to determine the own position. A range measurement error models based on measured data from real ranging devices is considered and we propose a multilateration cooperative algorithm that, without the need of measurements between targets, exploit the estimated position of cooperative nodes to increase localization performance. We examine the case where multiple targets are present in the same environment and how the position accuracy is affected by the cooperative nodes positions and by the availability of priori information about the environment and network geometry. Using numerical results based on experimental data, we demonstrate the impact of cooperation on the positioning accuracy. It is shown that, depending on the geometric configuration of the nodes, cooperation is not always advantageous

Effects of Power Allocation and Reuse Distance in Relay-Assisted Wireless Communications with Mutual Interference

Cooperative communication techniques effectively improve performance and coverage of wireless networks. This requires to find proper methods to allocate power among source and relay nodes. When others cells with sources, destinations, and relays are present, the mutual interference can be a limiting factor which needs to be characterized. In this paper we investi- gate the effects of relay position and power allocation strategy for cooperative communications employing space-time codes (STCs) under interference constraints due to a second cell with relay that reuse the resources. We characterize links between each source, relay, and destination to analyze power allocation methods with interference in realistic scenarios. The frame error rate at the destination for various channel conditions, available diversity, relays positions, power allocation, and amount of interference is then obtained. Results are shown for cooperative pragmatic STC in block fading channel (BFC) and provide insights on how to allocate the power based on links geometry and mutual interference considerations

Cooperative UWB based positioning systems: CDAP algorithm and experimental results

The need for accurate positioning has attracted significant interest in recent years, especially in cluttered environments where signals from satellite navigation systems are not reliable. Positioning systems based on ultrawide bandwidth (UWB) technology have been considered for these environments due to the property of UWB signals to resolve multipath and penetrate obstacles. However, localization techniques based solely on ranging typically lack accuracy and reliability in dense cluttered environments, due to line-of-sight (LOS) blockage and excess propagation delay through material. In this paper, we consider positioning in a typical indoor environment scenario, where ranging is subject to estimation error and excess delay. Beacons are deployed in known locations, and one or more target nodes wish to determine their positions. We consider a range measurement error models based on measured data from real ranging devices. These models are used in a multilateration cooperative algorithm we propose to determine the target position. So we examine the case where multiple targets are present in the same environment and how the position accuracy is affected by the cooperative nodes positions and by the availability of priori information about the environment and network geometry. Using numerical results, we demonstrate the impact of cooperation on the positioning accuracy. It is shown that, depending on the geometric configuration of the nodes, cooperation is not always advantageous

Effects of relay position and power allocation in space-time coded cooperative wireless systems

Cooperative communications are effective in improving the performance and extend the coverage of wireless networks. One issue is to find proper methods to allocate cooperative nodes. In this paper we investigate the effects of relay position and power allocation strategy in cooperative communications employing STC. We consider non-ideal links between source, relay, and destination enabling the analysis of relay allocation problem based on the performance of each link in realistic scenarios. The frame error rate for various channel conditions, available diversity, relays position, and transmitted power levels is obtained. Both the situation of balanced and unbalanced transmit power levels for source, relay, and destination are compared. Cooperative pragmatic STC in BFC are considered for our analysis. The results provide insights on how to allocate relay nodes based on geometry, link quality, and transmitted power considerations