105 research outputs found
Randomized Polar Codes for Anytime Distributed Machine Learning
We present a novel distributed computing framework that is robust to slow
compute nodes, and is capable of both approximate and exact computation of
linear operations. The proposed mechanism integrates the concepts of randomized
sketching and polar codes in the context of coded computation. We propose a
sequential decoding algorithm designed to handle real valued data while
maintaining low computational complexity for recovery. Additionally, we provide
an anytime estimator that can generate provably accurate estimates even when
the set of available node outputs is not decodable. We demonstrate the
potential applications of this framework in various contexts, such as
large-scale matrix multiplication and black-box optimization. We present the
implementation of these methods on a serverless cloud computing system and
provide numerical results to demonstrate their scalability in practice,
including ImageNet scale computations
Rateless Space-Time Block Codes for 5G Wireless Communication Systems
This chapter presents a rateless space-time block code (RSTBC) for massive multiple-input multiple-output (MIMO) wireless communication systems. We discuss the principles of rateless coding compared to the fixed-rate channel codes. A literature review of rateless codes (RCs) is also addressed. Furthermore, the chapter illustrates the basis of RSTBC deployments in massive MIMO transmissions over lossy wireless channels. In such channels, data may be lost or are not decodable at the receiver end due to a variety of factors such as channel losses or pilot contamination. Massive MIMO is a breakthrough wireless transmission technique proposed for future wireless standards due to its spectrum and energy efficiencies. We show that RSTBC guarantees the reliability of the system in such highly lossy channels. Moreover, pilot contamination (PC) constitutes a particularly significant impairment in reciprocity-based multi-cell systems. PC results from the non-orthogonality of the pilot sequences in different cells. In this chapter, RSTBC is also employed in the downlink transmission of a multi-cell massive MIMO system to mitigate the effects of signal-to-interference-and-noise ratio (SINR) degradation resulting from PC. We conclude that RSTBC can effectively mitigate such interference. Hence, RSTBC is a strong candidate for the upcoming 5G wireless communication systems
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