1,721,185 research outputs found
On the inverse symbol-error probability for diversity reception
No full textThis paper addresses the problem of finding the inverse symbol-error probability (SEP) expression for coherent detection of M-ary phase-shift keying with multichannel reception and maximal ratio combining in Rayleigh fading. To this aim, we derive upper and lower bounds on SEP that are simply invertible and uniformly tight for all values of signal-to-noise ratio. This enables us to obtain tight bounds on the inverse SEP and on the symbol-error outage (SEO), i.e., SEP-based outage probability. As an example of application to digital mobile radio, the SEO in a log-normal shadowing environment is analyzed
QoS-based outage probability for diversity reception
No full textIn a digital mobile radio system with fast fading superimposed on slow fading, the symbol error probability (SEP) alone is not sufficient to describe the link quality. In this case, a reasonable performance measure related to the slow channel variations is the outage probability (OP). This paper addresses the problem of evaluating SEP-based OP for multichannel reception with maximal ratio combining (MRC). To this end, we derive upper and lower bounds on the OP from upper and lower bounds on the inverse SEP respectively. As an example of application to digital mobile radio, the SEP-based outage probability in a log-normal shadowing environment is analyzed
Multi-channel reception for slow adaptive M-QAM in fading channels
No full textIn this letter we investigate the performance of slow adaptive M -ary quadrature amplitude modu-
lation with coherent multichannel reception. We consider a slow adaptive modulation (SAM) technique
which adapts the constellation size to the slow variation of the channel due, for example, to shadowing.
The proposed SAM technique is more practical than conventional adaptive modulation techniques that
require the adaptation to fast fading variations. Our results show that SAM technique can provide
substantial increase in throughput while maintaining an acceptable low bit error outage
Establishing High-Fidelity Entanglement in Quantum Repeater Chains
No full textEntanglement is crucial for many applications such as quantum computing, quantum sensing, and quantum communication. Establishment of entanglement between remote nodes, referred to as remote entanglement establishment (REE), is a key element of the quantum internet. This paper develops a theoretical framework for establishing high-fidelity entanglement between two remote nodes of a quantum repeater chain via entanglement generation, distillation, and swapping operations. In particular, an upper bound on the optimal REE rate under minimum fidelity requirements is established, and an REE policy that achieves such a bound asymptotically is presented. Results in this paper provide guidelines for protocol design in the quantum internet
On the performance of slow adaptive M-QAM with antenna subset diversity in fading channels
No full textIn this paper, we investigate the performance of adaptive M-ary quadrature amplitude modulation with antenna subset diversity. We consider a slow adaptive modulation (SAM) technique which adapts the constellation size to the slow variation of the channel due, for example, to shadowing. Our results show that the SAM technique can provide substantial increase in throughput with respect to fixed schemes while maintaining an acceptable low bit error outage. We also compare SAM with a fast adaptive modulation (FAM) technique, which tracks fast fading variations, showing that the throughput of SAM is close to that of FAM despite the fact that SAM is less complex and requires a lower feedback rate to the transmitter
AN ASYMPTOTICALLY ACHIEVABLE RATE BOUND FOR ESTABLISHING HIGH-FIDELITY ENTANGLEMENTS IN QUANTUM NETWORKS
No full textSlow adaptive M-QAM with diversity in fast fading and shadowing
No full textThis paper investigates the performance of adaptive M-ary quadrature amplitude modulation (QAM) with antenna subset diversity. We consider a slow adaptive modulation (SAM) technique that adapts the constellation size to the slow variation of the channel due, for example, to shadowing. The proposed SAM technique is more practical than conventional fast adaptive modulation (FAM) techniques that require adaptation to fast-fading variations. Our results show that the SAM technique can provide a substantial increase in throughput with respect to fixed schemes while maintaining an acceptable low bit-error outage. We also compare SAM and FAM techniques, showing that the throughput of SAM can be, in many practical cases, close to that of FAM, despite the fact that SAM is less complex and requires a lower feedback rate. For example, using a set of possible modulations {4,16,64}-QAM with dual-branch maximal ratio combining reception, 5% outage at a bit-error probability of 10-2 and a median signal-to-noise ratio of 22 dB, SAM is capable of improving the mean spectral efficiency of fixed schemes from about 1.9 to 4.7 b/s/Hz, which is close to the 5.5 b/s/Hz achieved by FA
Analysis of the BEP for M-QAM in fading channels
No full textThis work addresses the evaluation of
the bit error probability (BEP) for coherent detection
of M-ary quadrature amplitude modulation (M-
QAM) signals perturbed by additive white Gaussian
noise (AWGN) over Rayleigh fading channels. Exact
evaluation, approximations and a new tight upper
bound for the BEP are proposed
Network navigation with scheduling: Distributed algorithms
No full textNetwork navigation is a promising paradigm for enabling location awareness in dynamic wireless networks. A wireless navigation network consists of agents (mobile with unknown locations) and anchors (possibly mobile with known locations). Agents can estimate their locations based on inter- and intra-node measurements as well as prior knowledge. With limited wireless resources, the key to achieve high navigation accuracy is to maximize the benefits of agents’ channel usage. Therefore, it is critical to design scheduling algorithms that adaptively determine with whom and when an agent should perform inter-node measurements to achieve both high navigation accuracy and efficient channel usage. This paper develops a framework for the design of distributed scheduling algorithms in asynchronous wireless navigation networks, under which the algorithm parameters are optimized based on the evolution of agents’ localization errors. Results show that the proposed algorithms lead to high-accuracy, efficient, and flexible network navigation
mmWave Communications for High Mobility Devices: The Case of Road Side Links
No full textMobile communication at millimeter-waves (mmWaves) is affected by the rapid and random variations of the wireless environment. This requires accurate channel estimation at the receiver to compensate for the channel dynamics. The required channel training overhead has been shown to occupy a considerable fraction of the mmWave transmission bandwidth, especially when the mobile device (MD) moves at high-speed. We cope with the issue of the rapid variation of the channel by introducing a coherent transmission/detection technique, whose mechanism requires that MD has prior knowledge of its position as an alternative to the channel estimate. In particular, we consider the case of road side links with high-speed MDs and derive a closed-form expression for the optimal detector. We show that the proposed approach reduces the training overhead significantly at the expense of a signal-to-noise ratio (SNR) increase for a given bit error rate
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