Srinivas Yerramalli

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The quest for higher data rates in WiFi is leading to the development of standards that make use of wide channels (e.g., 40MHz in 802.11n and 80MHz in 802.11ac). In this paper, we argue against this trend of using wider channels, and instead advocate that radios should communicate over multiple narrow channels for efficient and fair spectrum utilization. We(More)
—Employing Orthogonal Frequency Division Multi-plexing (OFDM) signaling over time-varying channels results in inter-carrier interference (ICI) and degraded detection error probability due to the loss of orthogonality among the subcarriers. This problem is particularly exacerbated for systems operating in highly mobile scenarios such as underwater acoustic(More)
— This paper presents coordination and data fusion methods for teams of vehicles performing target search tasks without guaranteed communication. A fully distributed team planning algorithm is proposed that utilizes limited shared information as it becomes available, and data fusion techniques are introduced for merging estimates of the target's position(More)
— We address the effects of the aquatic communication channel constraints on the control performances of marine robot teams. The aquatic acoustic channels suffer from significant frequency and distance dependent attenuation, extensive time-varying multipath, motion-induced Doppler distortion and extreme channel latency due to the low speed of sound.(More)
—Cooperation between rational users has emerged as a new networking paradigm to improve the performance of wireless networks. In this paper, transmitter cooperation between wireless nodes in a Gaussian multiple access channel is studied under the framework of coalitional game theory. The stability of the grand coalition, the coalition of all users, is(More)
Signal scaling due to Doppler in underwater acoustic communications results in inter-carrier interference (ICI) and severely degraded detection performance in OFDM based systems in the absence of interference mitigation. Using a recently proposed partial FFT demodulation technique [5], where several FFT demodulators operate over parallel non-overlapping(More)
Channel estimation algorithms for Orthogonal Frequency Division Multiplexing (OFDM) employed in underwater acoustic (UWA) channels are investigated. Due to the slow propagation speed of acoustic waves, the compression and dilation effect on the time domain waveform warrant explicit time-varying Doppler scale estimation and compensation. In UWA channels, the(More)
—Fast and accurate Carrier Frequency Offset (CFO) estimation is a problem of significance in many multi-carrier modulation based systems, especially in uplink Orthogonal Frequency Division Multiple Access (OFDMA) where the presence of multiple users exacerbates the inter-carrier interference (ICI) and results in multiuser interference (MUI). In this paper,(More)