Location-based services (LBS) are an integral part of the mobile ecosystem today, relying on the Global Positioning System (GPS) and other technologies. However, while these technologies have been highly successful at positioning outdoors, they either fail to obtain a fix or do not provide the necessary accuracy indoors. In this paper, we will describe a low-cost high-accuracy indoor positioning system that can run on mobile devices. The system has high-accuracy because it combines several sources of information, thus improving accuracy over using any one of them alone. The cost is low because the sources of information used by the system such as WiFi measurements, inertial sensor data and building maps are readily available for use on a mobile device.

The wide choices of deployment parameters in next generation wireless communication systems, such as flexible bandwidth allocation, synchronous/asynchronous modes, FDD/TDD, full/half duplex, and configurable cyclic prefix duration, etc., present significant challenges in preamble and system acquisition design. This paper addresses these challenges, as well as the solutions provided by the 3GPP2 Ultra Mobile Broadband (UMB) standard. The proposed preamble design facilitates the maximal flexibility of the system configuration and yet has low overhead, low acquisition latency, and low complexity. Although the design is discussed under the UMB context, it also serves as a preamble design paradigm for an OFDMA communication system in general.

We investigate the performance of iterative decoding algorithms for multistep majority logic decodable (MSMLD) codes of intermediate length. We introduce a new bit-flipping algorithm that is able to decode these codes nearly as well as a maximum-likelihood decoder on the binary-symmetric channel. We show that MSMLD codes decoded using bit-flipping algorithms can outperform comparable Bose-Chaudhuri-Hocquenghem (BCH) codes decoded using standard algebraic decoding algorithms, at least for high bit-flip rates (or low and moderate signal-to-noise ratios (SNRs)).

In this paper, a special class of wireless networks, called wireless erasure networks, is considered. In these networks, each node is connected to a set of nodes by possibly correlated erasure channels. The network model incorporates the broadcast nature of the wireless environment by requiring each node to send the same signal on all outgoing channels. However, we assume there is no interference in reception. Such models are therefore appropriate for wireless networks where all information transmission is packetized and where some mechanism for interference avoidance is already built in. This paper looks at multicast problems over these networks. The capacity under the assumption that erasure locations on all the links of the network are provided to the destinations is obtained. It turns out that the capacity region has a nice max-flow min-cut interpretation. The definition of cut-capacity in these networks incorporates the broadcast property of the wireless medium. It is further shown that linear coding at nodes in the network suffices to achieve the capacity region. Finally, the performance of different coding schemes in these networks when no side information is available to the destinations is analyzed

We determine the capacity of a certain class of wireless erasure relay networks. We first find a suitable definition for the "cut-capacity" of erasure networks with broadcast at transmission and no interference at reception. With this definition, a maxflow mincut capacity result holds for the capacity of these networks.

This paper studies the performance of two classes of rateless codes (LTand Raptor codes) on noisy channels such as the BSC and the AWGNC. We find that Raptor codes outperform LT codes, and have good performance on a wide variety of noisy channels.