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This paper generalizes the piggybacking constructions for distributed storage systems by considering various protected instances and piggybacked instances. Analysis demonstrates that the proportion of protected instances determines the average repair bandwidth for a systematic node. The generalized codes cost much less repair bandwidth than the previous piggybacking codes by optimizing the proportion...
In this paper, we propose a new downlink non-orthogonal multiuser superposition transmission scheme for future 5G cellular networks, which we refer to as the lattice partition multiple access (LPMA). In this proposed design, the base station transmits multilevel lattice codes for multiple users. Each user's code level corresponds to a distinct prime and is weighted by a product of all distinct primes...
In this work, we examine the secrecy capacity region of the block-fading broadcast channel with confidential messages (BCC) when the transmitter has limited knowledge of the channel. In particular, we consider a two-user communication system where the transmitter has one common message to be transmitted to both users and one confidential message intended to only one of them. The confidential message...
In this work, we study data shaping codes for flash memory. We first review a recently proposed direct shaping code for SLC (one bit per cell) flash memory that reduces wear by minimizing the average fraction of programmed cells. Then we describe an adaptation of this algorithm that provides data shaping for MLC (two bits per cell) flash memory. It makes use of a page- dependent cost model and is...
In this paper, we study the power-efficient resource allocation for multicarrier non-orthogonal multiple access (MC-NOMA) systems. The resource allocation algorithm design is formulated as a non-convex optimization problem which takes into account the statistical channel state information at transmitter and quality of service (QoS) constraints. To strike a balance between system performance and computational...
We investigate the outage and decoding-delay performances for full-duplex (FD) decode-forward (DF) relaying with backward and sliding window decoding. In our analysis, we consider a block fading channel with full channel state information (CSI) availability at receivers and with limited CSI at transmitters. For backward decoding where the destination starts decoding from the last transmission block,...
We propose a novel approach to modulation coding using the Generalized Belief Propagation (GBP) algorithm. The idea is to completely eliminate a constrained encoder and, instead, embed a constraint into an error correction codeword by deliberately flipping the bits that violate the constraint. The GBP algorithm is used to keep the number of flipped bits small in order not to overburden the decoder...
The most popular methods for the analysis of LDPC codes, e.g. density evolution and EXIT charts, apply to infinite length ensembles. Finite length analysis is less common, among the notable examples are scaling law analysis and the EXIT band chart. The scaling law is limited to the waterfall region and furthermore is limited to the final error rates and does not give insight into the progression and...
Abstract-We consider the problem of designing constellation sets for multistage systems for high spectral efficiencies. In particular we will focus on two-stage systems where the cascaded decoding stages are associated to three types of receivers with different complexities and performances. The optimal receiver (S) processes the symbol LLR and delivers the maximum possible throughput, the simpler...
Due to their lack of assessment mechanisms of link quality in VANET environments, routing protocols do not deal efficiently with highly volatile links. One way to fill this gap would be to anticipate links breakages with new route computation. Currently available link quality indicators are not sufficiently responsive to consider forecasting. In this paper we present a novel predictive link quality...
In this paper, an underlay based cognitive radio network (CRN) consisting of a secondary base station (SBS), a secondary receiver (SR), an energy harvesting node (EHN), and a primary transmitter-receiver (PT-PR) pair, is considered. The EHN is assumed to have a power splitter (PS) at the receiver to decode information and harvest energy simultaneously from the SBS transmission, thus reducing the secrecy...
Many aspects of lattice coding and decoding under time-varying multiple-antenna systems remain unexplored. This paper studies the achievable rates using lattice codes for the multiple-input- multiple-output (MIMO) point-to-point channel with ergodic fading and channel state information at the receiver. The proposed lattice coding scheme involves the use of decision regions that are universal for almost...
In this paper, we analyze the performance of a single-relay network in which the reliability is provided by means of Random Linear Network Coding (RLNC). We consider a scenario when both source and relay nodes can encode packets. Unlike the traditional approach to relay networks, we introduce a passive relay mode, in which the relay node simply retransmits collected packets in case it cannot decode...
This paper presents initial results for a novel 128-antenna massive Multiple-Input, Multiple- Output (MIMO) testbed developed through Bristol Is Open in collaboration with National Instruments and Lund University. We believe that the results presented here validate the adoption of massive MIMO as a key enabling technology for 5G and pave the way for further pragmatic research by the massive MIMO community...
We propose and design a lattice coded physical- layer network coding (PNC) over a finite complex number field Z[ω]/ξZ[ω] in a two-way relay channel (TWRC). In our design, we construct the lattice codes from an irregular repeat- accumulate (IRA) code over GF(q). A randomly generated coset is employed to our scheme to ensure that the codes exhibit permutation invariance and...
In this paper, we develop a joint channel estimation and decoding method for faster-than-Nyquist signaling (FTNS) transmitting over (quasi-static) time-varying frequency-selective fading channels based on the variational Bayesian (VB) framework. In contrast to existing methods, ours is capable of performing explicit frequency-domain channel estimation and decoding in a turbo mode without requiring...
Caching of popular multimedia content at small-cell base stations (BSs) is a promising solution to reduce the traffic load of macro-BSs without relying on a high-speed backhaul architecture. While most prior work analyzed the effect of smallcell caching, or femto-caching, under the assumption of negligible interference between macro-BS and small-cell BS, this paper contributes to a more recent line...
Cloud radio access network (CRAN) is a promising candidate for the next-generation wireless communication systems. In CRAN, remote radio heads (RRHs) are deployed to serve users in a target area, which are connected to a central processor (CP) via limited-capacity links termed the fronthaul. In practice, the large amount of information transferred between each RRH and the CP for centralized processing...
Wireless communication systems use adaptive modulation and coding (AMC) as well as hybrid ARQ (HARQ) to mitigate the effects of time-varying and error-prone channels. In this work, we analyze the benefits of combining HARQ and AMC adopting the throughput as a unique performance measure. The analysis of block-fading channels and error-prone decoders allows us to conclude that i) adding HARQ on top...
Partially overlapped channels (POCs) have been studied recently to improve network performance. However, the current OFDM-based 802.11 system is designed for co-channel communication, and does not support communication over POCs. Thus the coordination between POCs imposes a new challenge to WLANs. In this paper, we present DSN (Data Symbol Nulling), a novel communication strategy that leverages the...
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