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In this paper, a high throughput pipeline HARQ scheme of polar codes is proposed as the throughput of conventional schemes are to be promoted. In this scheme, we use a pipeline structure that the current HARQ process may combine the source bits of the current process and the retransmission bits of the incorrectly decoded previous HARQ processes and the source bits of the current process may be retransmitted...
Licensed-Assisted Access Long-Term Evolution (LAA- LTE) framework can offload excessive data stream to the unlicensed spectrum. Devices from different operators will compete for the same band and have to endure a more complex and congested channel conditions. Therefore a rapid and efficient access mechanism should be introduced in the LAA framework. Based on the Type B LBT channel access scheme, this...
We propose a decentralized multi-cell aware opportunistic random access (MA-ORA) protocol that almost achieves the optimal throughput scaling in a K-cell random access network with one access point (AP) and N users in each cell. Under our MA-ORA protocol, users opportunistically transmit with a predefined physical layer data rate in a decentralized manner if the desired signal power to the serving...
In this paper, throughput of hybrid automatic repeat request (HARQ) schemes with finite blocklength codes is studied for both constant-rate and ON-OFF discrete-time Markov arrivals under statistical queuing constraints and deadline limits. After analyzing the decoding error probability and outage probability, the distribution of transmission period is characterized, and the throughput expressions...
Alice and Bob want to exchange information over an additive interference channel that also contains a malicious eavesdropper-jammer James who aims to disrupt this two-way communication. In the baseline model (motivated by wireless jamming scenarios), Alice and Bob transmit length-n q-arj encodings xA and xB respectively of their own messages. James observes the interference pattern z = xA + xB, and...
This paper presents the first Network-Coded Multiple Access (NCMA) system with multiple users adopting different signal modulations, referred to as rate-diverse NCMA. A distinguishing feature of NCMA is the joint use of physical-layer network coding (PNC) and multiuser decoding (MUD) to boost throughput of multipacket reception systems. In previous NCMA systems, users adopt the same modulation regardless...
Variable-length codes with incremental redundancy controlled by feedback allow a system to approach capacity with short average blocklengths and thus relatively low-complexity decoders. This paper shows how to use those same variable-length codes with incremental redundancy to approach capacity without feedback. The general principle is to provide a common pool of redundancy that can be accessed by...
Sparse code multiple access (SCMA) is a new type of non-orthogonal modulation suggested for 5G systems offering lower bit-error rate and higher spectral efficiency. There are many challenges when designing high throughput SCMA message passing decoders to meet the standards expected from 5G networks. Particularly, the message passing algorithm (MPA) needs many exponential computations to calculate...
This work presents the first integration of a message-passing detector (MPD) and a polar decoder. A soft-output MPD, which is essential to approach the channel capacity, is first proposed. Compared to the state-of-the-art design, the proposed MPD achieves a 6.9x higher throughput with 49% lower energy, despite the soft outputs. The proposed polar decoder achieves a 1.35x higher throughput with comparable...
This paper presents a Non-Binary LDPC decoder with information throughput of 2.267Gbps and power consumption of 212.4mW, yielding an energy efficiency of 93.7pJ/b, implemented in a 40nm CMOS technology. The employed code is long and high-rate without degree-2 variable nodes, resulting in a low error floor. A dual decoding algorithm scheme alleviates the computational complexity of decoding, realized...
Data movement to and from off-chip memory dominates energy consumption in most video decoders, with DRAM accesses consuming 2.8x–6x more energy than the processing itself. We present a H.265/HEVC video decoder with embedded DRAM (eDRAM) as main memory. We propose the following techniques to optimize data movement and reduce the power consumption of eDRAM: 1) lossless compression is used to store reference...
This paper uses a case study of a tail-biting convolutional code (with successful decoding indicated by the reliability output Viterbi algorithm) to present an information density approach for analyzing and optimizing the throughput of systems using incremental redundancy controlled by feedback. Polyan-skiy's normal approximation combined with a linear model for the information gap of a rate-compatible...
This paper investigates the design of secondary access policies which exploit the temporal redundancy of the retransmission protocol employed by primary users (PU) to improve the spectral efficiency of wireless networks. Secondary users (SU) perform selective retransmissions in order to optimize the potential of interference cancellation at the receiver. The corrupted signals are selectively buffered...
Deployed in various distributed storage systems, erasure coding has demonstrated its advantages of low storage overhead and high failure tolerance. Typically in an erasure-coded distributed storage system, systematic maximum distance seperable (MDS) codes are chosen since the optimal storage overhead can be achieved and meanwhile data can be read directly without decoding operations. However, data...
Interference between concurrent transmissions causes severe performance degradation in a wireless network. This paper addresses interference cancellation to enable simultaneous packet receptions at a node with a single radio in Wireless Sensor Networks (WSN). Interference cancellation is particularly important for WSN as most of its applications rely on convergecast where all the traffic in the network...
Uplink grant-free non-orthogonal multiple access (NOMA) is promising for machine-to-machine (M2M) communications to meet the requirement of sporadic short packets transmission of massive devices. In this paper, successive interference cancellation (SIC) and joint decoding (JD), as two well-known decoding techniques for NOMA, are analyzed for M2M random access. Due to the sporadic small packet transmission,...
Covert communication is to achieve a reliable transmission from a transmitter to a receiver while guaranteeing an arbitrarily small probability of this transmission being detected by a warden. In this work, we study the covert communication in AWGN channels with finite blocklength, in which the number of channel uses is finite. Specifically, we analytically prove that the entire block (all available...
Network-coded (NCed) automatic repeat request (ARQ) techniques have been shown to provide significant throughput improvements over basic ARQ systems in two-way wireless systems. Most results derived so far, however, used the assumption of no extra overhead. In practical systems, NCed-ARQ requires more information exchange between base-station and end-nodes, and therefore it is crucial to study the...
We consider a dual-hop wireless network where an energy constrained relay node first harvests energy through the received radio-frequency signal from the source, and then uses the harvested energy to forward the source's information to the destination node. The throughput and delay metrics are investigated for a decode-and-forward relaying mechanism at finite blocklength regime and delay-limited transmission...
Recently, data transmission has become more important in our daily life. The developments of communication component are diverging with electromagnetic (EM) techniques. According to the popularity of wireless communications, the limitations of transmission also appear. Especially, electromagnetic interference (EMI) and frequency spectrum shortage would limit the application of wireless communication...
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