John M. Shea

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We propose a new hybrid ARQ scheme that utilizes reliability estimates generated by soft-input, soft-output (SISO) decoders. The ARQ scheme that we propose transmits additional information for the unreliable bits, and this information is used to do additional decoding. We present results that show this ARQ technique can provide performance close to the(More)
Secret sharing over the fast-fading MIMO wiretap channel is considered. A source and a destination try to share secret information over a fast-fading MIMO channel in the presence of a wiretapper who also makes channel observations that are different from but correlated to those made by the destination. An interactive authenticated unrestricted public(More)
In wireless ad hoc networks (WANets), multihop routing may result in a radio knowing the content of transmissions of nearby radios. This knowledge can be used to improve spatial reuse in the network, thereby enhancing network throughput. Consider two radios, Alice and Bob, that are neighbors in a WANet not employing spread-spectrum multiple access. Suppose(More)
A coding scheme based on irregular low-density parity-check (LDPC) codes is proposed to send secret messages from a source over the Gaussian wiretap channel to a destination in the presence of a wiretapper, with the restriction that the source can send only binary phase-shift keyed (BPSK) symbols. The secrecy performance of the proposed coding scheme is(More)
Multi-packet reception (MPR) has recently received attention for use in military wireless ad hoc networks because of the potential to greatly improve spatial reuse. However, MPR typically requires complicated hardware that makes it prohibitive to implement in many current military platforms. An alternative, cross-layer approach is to use an overlapped(More)
In previous studies we showed that a Cryptococcus neoformans mutant lacking glucosylceramide (Deltagcs1) is avirulent and unable to reach the brain when it is administered intranasally into an immunocompetent mouse and is contained in a lung granuloma. To determine whether granuloma formation is key for containment of C. neoformans Deltagcs1, we studied the(More)
One of the most promising approaches to improving communication efficiency in wireless communication systems is the use of multiuser diversity. Although it has been widely investigated and shown feasible and efficient in cellular networks, there is little work for the ad hoc networks, especially in real protocol and algorithm design. In this paper, we(More)