Communication complexity

About: Communication complexity is a research topic. Over the lifetime, 3870 publications have been published within this topic receiving 105832 citations.

Coding for interactive computation: Progress and challenges

Abstract: We highlight some recent progress and challenges in the area of interactive coding and information complexity.

Deterministic Communication vs. Partition Number

Abstract: We show that deterministic communication complexity can be superlogarithmic in the partition number of the associated communication matrix. We also obtain near-optimal deterministic lower bounds fo...

Fast Convergence Time Synchronization in Wireless Sensor Networks Based on Average Consensus

Abstract: Average consensus theory is intensely popular for building time synchronization in wireless sensor network (WSN). However, the average consensus-based time synchronization algorithm is based on the iteration that poses challenges for efficiency, as they entail high communication cost and long convergence time in large-scale WSN. Based on the suggestion that the greater the algebraic connectivity the faster the convergence, a novel multihop average consensus time synchronization (MACTS) is developed with innovative implementation in this article. By employing multihop communication model, it shows that virtual communication links among multihop nodes are generated and algebraic connectivity of the network increases. Meanwhile, a multihop controller is developed to balance the convergence time, accuracy, and communication complexity. Moreover, the accurate relative clock offset estimation is yielded by delay compensation. Implementing the MACTS based on the popular one-way broadcast model and taking multihop over short distances, we achieve hundreds of times the MACTS convergence rate compared to average TimeSync (ATS).

Efficient equalizer update algorithms for acoustic communication channels of varying complexity

Abstract: Underwater acoustic communication channels vary from stationary with sparse arrivals to rapidly varying and fully reverberant. A receiver structure capable of operating over this wide range of characteristics has evolved and consists of a fractionally-spaced multi-channel combiner, a sparse DFE, and an embedded PLL. At the computational heart of this receiver is an adaptation algorithm, used to update the various equalizer parameters, The adaptation algorithm may use one of the standard strategies such as adaptive step-size LMS, RLS, adaptive memory RLS, or a hybrid of these. The choice of algorithm involves trade-offs between training time, tracking-rate, operating SNR, and computational requirements of the receiver. To maximize the receiver throughput, we wish to select the least computational algorithm for which the error-rate is still acceptable and, given the volatility of the underwater channel, this choice should be made for each received packet, In this paper, we compare the performance of several LMS and RLS adaptation algorithms over a range of real acoustic data. We show that the computationally-efficient adaptive step-size LMS performs well for many channel classes, but that the faster tracking of RLS is essential for some complex non-stationary channels. The results provide a first step towards the automatic selection of adaptation algorithm, as would be required in a fully autonomous receiver.

Chasing the Weakest System Model for Implementing Ω and Consensus

Abstract: Aguilera et al. and Malkhi et al. presented two system models, which are weaker than all previously proposed models where the eventual leader election oracle Omega can be implemented, and thus, consensus can also be solved. The former model assumes unicast steps and at least one correct process with f outgoing eventually timely links, whereas the latter assumes broadcast steps and at least one correct process with f bidirectional but moving eventually timely links. Consequently, those models are incomparable. In this paper, we show that Omega can also be implemented in a system with at least one process with f outgoing moving eventually timely links, assuming either unicast or broadcast steps. It seems to be the weakest system model that allows to solve consensus via Omega-based algorithms known so far. We also provide matching lower bounds for the communication complexity of Omega in this model, which are based on an interesting ldquostabilization propertyrdquo of infinite runs. Those results reveal a fairly high price to be paid for this further relaxation of synchrony properties.