A rapid prototyping framework for practical OFDMA systems using Software Defined Radios

Abstract

State-of-the-art wireless technologies such as LTE employ OFDMA to enable robust and efficient frequency-division multiple access, which is also promising for other scenarios, such as Wireless Mesh Networks. OFDMA can improve throughput by allocating subchannels to the users which experience the best performance on the corresponding frequencies. This has lead to a large body of work on subchannel allocation schemes which optimize throughput while guaranteeing fairness. However, most solutions are discussed at a purely theoretical and/or simulative level. In this paper, we provide a framework for prototyping such schemes on the WARP Software Defined Radio to obtain practical results with small implementation overhead. We design a mechanism which allows to analyze offline how a certain allocation technique would have performed in a previously measured scenario. Moreover, we show that our approach is stable and robust regarding practical issues. While we focus on Wireless Mesh Networks, our system can easily be adapted to infrastructure-based systems.

Leveraging an Agile RF Transceiver for Rapid Prototyping of Small-Cell Systems

“…The correctly received constellation points are marked green, whereas the erroneous constellation points are shown in red with straight lines connecting them to the transmitted symbol. In general, the constellation scatter plots are quite comparable to other WARPLab OFDM results in the literature [14]. This observation validates the over-the-air transmission capabilities of our SDR platform.…”

Evaluating dynamic OFDMA subchannel allocation for wireless mesh networks on SDRs

“…In order to circumvent this problem, we resort to a technique called Concurrent Measuring of Subchannel Performances (CMSP) [9] which exploits the coherence bandwidth of channels. We briefly introduce how it works, but details can be found in [9]. Essentially, the technique allows to measure all possible subchannel allocations in one single transmission, which eliminates the outdated CSI problem.…”

“…Additionally, we use the Subchannel Avoidance Gain (SAG) [9], which is a metric that uses the BER and the SER to determine if symbol errors become less severe due to a certain allocation s compared to a baseline b. Equation 1 shows how it relates both metrics.…”