[show abstract][hide abstract] ABSTRACT: Cooperative communication is a promising technique for future wireless networks, which significantly improves link capacity and reliability by leveraging broadcast nature of wireless medium and exploiting cooperative diversity. However, most of existing works investigate its performance theoretically or by simulation. It has been widely accepted that simulations often fail to faithfully capture many real-world radio signal propagation effects, which can be overcome through developing physical wireless network testbeds. In this work, we build a cooperative testbed based on GNU Radio and Universal Software Radio Peripheral (USRP) platform, which is a promising open-source software-defined radio system. Both single-relay cooperation and multi-relay cooperation can be supported in our testbed. Some key techniques are provided to solve the main challenges during the testbed development: e.g., maximum ratio combine in single-relay transmission and synchronized transmission among multiple relays. Extensive experiments are carried out in the testbed to evaluate performance of various cooperative communication schemes. The results show that cooperative transmission achieves significant performance enhancement in terms of link reliability and end-to-end throughput.
[show abstract][hide abstract] ABSTRACT: Content Distribution is a key application in an infrastructure-based wireless network. Existing works on this area use either pure broadcast transmission or pure unicast transmission. In this paper, we propose a hybrid broadcast-unicast transmission scheme to improve the efficiency of content distribution for wireless networks with multi-rate support. In the proposed scheme, access point broadcast packets to nodes within its transmission range with a deliberately selected broadcast rate. After that, the point-to-point unicast transmissions are exploited for data forwarding. It mitigates the inherit problems that comes from unicast and broadcast transmission respectively, such as severe contention and large amount of redundant re-transmission. Furthermore, cooperative communication is exploited as a physical layer technique to enhance the throughput of the network. A cooperative communication aware routing is designed accordingly, where the contention relationship between wireless links have been taken into consideration. Simulation results show that the proposed scheme outperforms existing schemes dramatically in terms of network throughput and transmission delay.
Global Telecommunications Conference, 2009. GLOBECOM 2009. IEEE; 01/2010