Multi-connectivity (MCo) is considered to be a key strategy for enabling reliable transmissions and enhanced data rates in fifth-generation mobile networks, as it provides multiple links from source to destination. In this paper, we quantify the communication performance of MCo in terms of outage probability and throughput. For doing so, we establish a simple, yet accurate analytical framework at high signal-to-noise ratio (SNR), in which the number of links, the spectral efficiency, the path loss, and the SNR are incorporated, giving new insights into the potentials of MCo as compared with the single-connectivity (SCo). These are our main contributions: 1) finding the exact coding gain of the outage probability for parallel block-fading channels; 2) quantifying the performance improvement of MCo over SCo in terms of SNR gain; and 3) comparing optimal and suboptimal combining algorithms for MCo at the receiver side, namely joint decoding, selection combining, and maximal-ratio combining, also in terms of SNR gain. In addition, we apply our analytical framework to real field channel measurements and thereby illustrate the potential of MCo to achieve high reliability and high data rates in real cellular networks.

How Reliable and Capable is Multi-Connectivity?

In this paper, we consider the power splitting relaying (PSR) and time switching relaying (TSR) protocols for decode-and-forward (DF)-based relay networks consisting of a source, a relay, and a destination. For the networks, the relay is assumed to have a rechargeable battery with a certain amount of remaining energy for energy harvesting through the received signal transmitted from the source. Specifically, for the PSR protocol with and without the direct-path, we present the outage probability expression with a given power splitting coefficient, and we obtain the optimum power splitting coefficient to maximize the transmission rate and derive its transmission rate and outage probability, where the optimum coefficient depends on channel conditions and remaining energy. For the TSR protocol with and without the direct-path, we present the outage probability expression with a given time switching coefficient, and we obtain the optimum time switching coefficient to maximize the transmission rate and derive its transmission rate, where the optimum coefficient also depends on channel conditions and remaining energy.

Maximum Transmission Rate of PSR/TSR Protocols in Wireless Energy Harvesting DF-Based Relay Networks

The study of the effects of Nakagami- $m$ fading channels with both integer and non-integer $m$ plays an important role in the design of practical wireless systems. In this paper, we investigate a dual-hop cooperative communication system, where source node communicates with destination node through direct and relaying paths. Partial relay selection (PRS) scheme is used to select the best relay among $N$ relays which are capable of harvesting energy from radio frequency (RF) signals. At the destination, selection combining (SC) technique is employed to combine the signals of the direct path and the relaying path. We consider two relaying protocols, i.e. amplify-and-forward (AF) and decode-and-forward (DF). For both AF and DF protocols, we derive the tight lower-bound closed-form approximate expression and the exact closed-form expression of the outage probability (OP) over Nakagami- $m$ fading channels with both integer and non-integer $m$ . Moreover, the optimal energy harvesting duration which minimizes the OP is also determined. Numerical results show that, the OP of DF protocol and its minimum value is lower than those of AF protocol for the same parameter settings. Moreover, the time switching ratio which gives the smallest OP in the case without direct path is larger than the case with direct path.

Outage Analysis of RF Energy Harvesting Cooperative Communication Systems Over Nakagami- $m$ Fading Channels With Integer and Non-Integer $m$

Convolutional coding and Viterbi decoding, along with binary phase-shift keyed modulation, is presented as an efficient system for reliable communication on power limited satellite and space channels. Performance results, obtained theoretically and through computer simulation, are given for optimum short constraint length codes for a range of code constraint lengths and code rates. System efficiency is compared for hard receiver quantization and 4 and 8 level soft quantization. The effects on performance of varying of certain parameters relevant to decoder complexity and cost is examined. Quantitative performance degradation due to imperfect carrier phase coherence is evaluated and compared to that of an uncoded system. As an example of decoder performance versus complexity, a recently implemented 2-Mbit/s constraint length 7 Viterbi decoder is discussed. Finally a comparison is made between Viterbi and sequential decoding in terms of suitability to various system requirements.

Viterbi Decoding for Satellite and Space Communication

Diversity-multiplexing tradeoff (DMT) was characterized asymptotically (SNR-> infinity) for i.i.d. Rayleigh fading channel by Zheng and Tse [1]. The SNR-asymptotic DMT overestimates the finite-SNR one [2]. This paper outlines a number of additional limitations and difficulties of the DMT framework and discusses their implications. Using the recent results on the size-asymptotic (in the number of antennas) outage capacity distribution, the finite-SNR, size-asymptotic DMT is derived for a broad class of fading distributions. The SNR range over which the finite-SNR DMT is accurately approximated by the SNR-asymptotic one is characterized. The multiplexing gain definition is shown to affect critically this range and thus should be carefully selected, so that the SNR-asymptotic DMT is an accurate approximation at realistic SNR values and thus has operational significance to be used as a design criteria. The finite SNR diversity gain is shown to decrease with correlation and power imbalance in a broad class of fading channels, and such an effect is described in a compact, closed form. Complete characterization of the outage probability (or outage capacity) requires not only the finite-SNR DMT, but also the SNR offset, which is introduced and investigated as well. This offset, which is not accounted for in the DMT framework, is shown to have a significant impact on the outage probability for a broad class of fading channels, especially when the multiplexing gain is small. The analytical results and conclusions are validated via extensive Monte-Carlo simulations. Overall, the size-asymptotic DMT represents a valuable alternative to the SNR-asymptotic one.

/pdf/finite-snr-diversity-multiplexing-tradeoff-via-asymptotic-4gacrwhtx7.pdf

Finite-SNR Diversity-Multiplexing Tradeoff via Asymptotic Analysis of Large MIMO Systems

The primary disadvantage of orthogonal frequency-division multiplexing (OFDM) is the high time-domain peak-to-average power ratio (PAR) that severely limits the transmitter power efficiency. The PAR can be globally minimized by distorting the OFDM constellation subject to a constraint on the error vector magnitude (EVM). In this paper, we demonstrate that an optimal amount of EVM exists for minimizing the transmitter power consumption while maintaining a constant bit error rate (BER) at the receiver. Alternatively, the EVM value may be chosen to maximize the channel capacity while maintaining a constant power consumption at the transmitter. Both EVM levels are only a function of the required signal-to-noise ratio at the OFDM receiver.

Computing the Optimal Amount of Constellation Distortion in OFDM Systems

Multiple antenna systems can be used to increase system reliability or to increase system capacity. Initially, space-time codes were designed to achieve one of these two types of gain. Recently, though, a tradeoff between these two system resources has been characterized by the diversity-multiplexing tradeoff. Achieving this optimal performance frontier requires proper coding. For diversity optimality, the signal transmitted from each antenna must redundantly describe the message bits. This redundancy has been quantified by the rate of a space-time code, which relates space-time codebook size to constituent single-input-single-output (SISO) constellation size. Achievable diversity has also been shown to decrease with increasing rates, which establishes the diversity-rate tradeoff. In this work, we consider a generalized notion of the rate of the space-time code, which we refer to as the code rate Rc, and the associated diversity-code rate tradeoff. We then generalize the diversity-multiplexing and diversity-code rate tradeoffs and find that a new diversity-multiplexing tradeoff exists as a function of the code rate.

Code Rate-Diversity-Multiplexing Tradeoff

MIMO wireless systems have been a focus of research for several years, mainly because of the promise of increased channel capacity, extended range, and increased reliability. An aspect of this ongoing research has been concerned with transmit precoding given partial information of the channel. This work focuses on designing a transmit covariance to minimize the probability of outage for a given target data rate over a fading MIMO channel whose distribution is known to the transmitter. This problem is addressed by formulating a convex problem via a heuristic relaxation. Structure of the problem is utilized to simplify the numerical implementation. Finally, the performance of this technique relative to other simpler techniques is considered, therefore showing the utility of this computational technique in evaluating other heuristics.

Minimizing outage probability for arbitrary channel distributions

Recently, there has been a great deal of interest on the performance of MIMO wireless systems as the MIMO fading channel offers an increase in capacity and reliability over that of a SISO channel. When channel state information is not known at the transmitter, the level of performance obtained depends on the degree of cooperation between the transmit antennas. With no cooperation between the antennas, horizontally coded spatial multiplexing is diversity suboptimal since each message bit is encoded and transmitted by only one antenna. An optimal scheme, on the other hand, codes message bits across all transmit antennas. This work generalizes and quantifies the level of cooperation between transmit antennas with the cooperation parameter R c and then finds upper and lower bounds for the achievable data rates for such a system using a scaled identity transmit covariance matrix. These bounds are found to be tight for certain values of Rc and the data rate Rt. Finally, these bounds are useful in computing the outage probability and diversity order of partially cooperative MIMO systems when channel state information is not known at the transmitter

Partially Cooperative MIMO Channels with Scaled Identity Transmit Covariance

MIMO wireless systems have been studied over the past few years due to the promise of increased capacity and reliability. Additional performance gains are possible when channel state information is available at the transmitter (CSI-T). In this work, we consider the case of partial CSI-T (channel transmit covariance) and revisit precoder design for high rate space-time codes which do not have a unique minimum error matrix. Using a set of minimum error matrices combined with traditional MIMO precoder design results in improved performance over that of previous design techniques based a single minimum error matrix.

On Precoding for High Spatial Rate Space-Time Codes

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

E. Stauffer

Author Tools

Chat about Author