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 Multiplexing (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)
Underwater acoustic channels (UACs) have a large fractional bandwidth and are well modeled by a multiscale–multilag model, which is a generalization of the commonly employed single time-scale model. The path-dependent time scaling introduces significant channel variation, destroying carrier orthogonality and yielding intercarrier interference (ICI) in an(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 from(More)
This paper presents novel data fusion methods that enable teams of vehicles to perform target search tasks without guaranteed communication. Techniques are introduced for merging estimates of a target's position from vehicles that regain contact after long periods of time, and a fully distributed team-planning algorithm is proposed, which utilizes limited(More)
Cooperation between nodes sharing a wireless channel is becoming increasingly necessary to achieve higher throughputs in a wireless network. The problem of determining the feasibility and stability of cooperation between rational nodes in a wireless network is of great importance in understanding cooperative behavior. This paper addresses the stability of(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)
In mobile OFDM systems, such as underwater acoustic and digital video broadcasting (DVB) systems, time variation causes severe inter-carrier interference (ICI) which limits data detection performance. To address this problem, a signal processing strategy using several partial-interval FFTs instead of a conventional full-interval single FFT is proposed.(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)
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 multi-user interference (MUI). In this paper,(More)