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This paper studies feedback stabilization of a linear time-invariant (LTI) discrete-time system with information constraints in the input channels, described by additive white Gaussian noise (AWGN). A signal-to-noise ratio (SNR) constraint model is adopted in studying its communication capacity limits. Upper and lower bounds of the least capacity are derived for feedback stabilization in both state...
We present an analytical approach for determining the signal-to-noise-ratio (SNR) of m multiple antennas in the line-of-sight case. The antennas are placed at random positions within a disc of given diameter d. We characterize the angular signal strength with three sectors: the main beam, the side beams and an area of white Gaussian noise. The SNR and the sector angles depend on d, m, and the wavelength...
Multiple input multiple output (MIMO) communication architecture has spectral efficiencies far beyond those offered by conventional techniques, and is greatly to increase the channel capacity. In this paper, we investigate the MIMO channel capacity in correlated channels using the uniform angular distribution, numerical simulations are performed with Matlab to verify the proposed formula. We prove...
Closed-form expressions for the channel capacity of an L-branch equal gain combining diversity receiver over Hoyt (Nakagami-q) fading channels is derived for adaptive transmission schemes. To obtain capacity expressions, probability density function of the combiner out put signal-to-noise ratio (SNR) is used. The capacity expressions are given in terms of Yacoub's integral, a general solution for...
A method to approach the capacity of Multiple Access Channel by means of power allocation was studied. By applying PAM modulation to each individual signal and superimposing the weighted signal together, we treated MAC channel as single user multiple level coding and modulation system. We found that the searched power profile was more powerful in terms of approaching MAC capacity than that obtained...
A multiple-input multiple-output two-way relay channel consisting of two communication nodes and a full-duplex relay node is considered, assuming that no direct link exists between the two communication nodes. We propose an achievable scheme using lattice codes combined with generalized singular value decomposition-based precoding for the first phase and vertically encoded structural bining for the...
In this paper, we study the problem of stabilizability of LTI systems over both the forward (from the controller to the plant) and feedback (from the sensor to the controller) channel. We adopt the additive white noise (AWN) channel with a prescribed power constraint as our channel model. For first order systems, we derive explicitly the necessary and sufficient conditions for stabilizability and...
This paper studies the inter-vehicular communication (IVC) system where a vehicle transmits information to another vehicle assisted by an access point (AP), which may be mounted along a street or on a rooftop. The paper first presents the double-Rayleigh fading vehicle-to-vehicle (V2V) channel model and the amplify-and-forward (AF) relaying system. And then the optimal power allocation (OPA) solutions...
In this paper, we investigate decode-and-forward (DF) cooperative diversity over independent and identically distributed (i.i.d) Weibull fading channel using selection combining (SC) technique, derive a closed form expression for the probability density function (PDF) of the signal-to-noise ratio (SNR) for the Weibull fading distribution, and obtain closed form expressions for the average symbol error...
Upper bounds on link spectral efficiency of amplify-and-forward cooperative diversity networks with independent but non-identically distributed wireless fading statistics are studied by deriving the Shannon capacity of three distinct adaptive source transmission techniques: (i) constant power with optimal rate adaptation (ORA); (ii) optimal joint power and rate adaptation (OPRA); and (iii) fixed rate...
The paper introduces an asymptotic series expansion for the mutual information of Multiple-Input Multiple-Output (MIMO) channels. For low signal to noise ratio (SNR) the first term of expansion approaches mutual information from below. Using the low SNR approximation a new water filling power allocation at the transmitter is derived when the receiver and the transmitter have perfect channel state...
This paper studies the relay-assisted inter-vehicular communications (IVCs) with double Rayleigh fading vehicle-to-vehicle links. The OPA (optimal power allocation) solution is derived through maximizing source-to-destination channel capacity assuming amplify-and-forward relaying. The outage performance is discussed and the lower bound on outage probability at medium to high SNR (signal-to-noise ratio)...
The presence of line-of-sight (LoS) components is usually regarded as a limiting factor for multiple-input multiple-output (MIMO) systems due to the lower multiplexing gains compared to the prevalent independent and identically (i.i.d.) Rayleigh fading model. In this paper, we present a versatile methodology for maximizing LoS-MIMO capacity at any operating signal-to-noise ratio (SNR) by capitalizing...
A multiple-antenna Gaussian wiretap channel in which the number of antennas at the source is not larger than that at the eavesdropper is considered. Without feedback, the secrecy capacity over such a channel generally converges to a constant at high signal-to-noise ratio (SNR). A half-duplex secure protocol allowing the destination to actively broadcast random keys over insecure channels is proposed...
Cooperative-diversity networks have recently been proposed as an effective technique to form virtual antenna arrays without using collocated multiple antennas. In this paper, we consider the adaptive decode-and-forward (DF) cooperative-diversity system with the Nth best-relay selection scheme. In the best-relay selection scheme, from the set of M relays the best relay only forwards the source signal...
Cognitive radio with spectrum sharing feature is a promising technique to address the spectrum under-utilization problem in dynamically changing environments. In this paper, achievable capacity gain of spectrum sharing systems over dynamic fading environments is studied. For the analysis, a theoretical fading model called hyper fading model that is suitable to the dynamic nature of cognitive radio...
In this paper, we investigate cooperative diversity using amplify-and-forward (AF) relaying over independent and identically distributed (i.i.d.) Weibull fading channels with selection combining (SC) and derive a approximate closed form expression for the probability density function (PDF) of the signal-to-noise ratio (SNR) for the Weibull fading distribution, Then closed form expression for the average...
Unequal error protection (UEP) and rateless coding are both methods used to combat channel uncertainty. With a rateless code, the code rate automatically adapts to the channel quality through the use of incremental redundancy. However, a rateless code lacks the ability to differentiate priorities and all bits suffer the same long delay in poor channel conditions. In contrast, UEP ensures reliable...
The paper reports on investigations into the relationship between the channel estimation and the channel effective degree of freedom (EDOF) for a Multiple Input Multiple Output (MIMO) wireless communication system. It is pointed out that both the channel estimation and EDOF, in conjunction with an assumed signal to noise ratio (SNR), affect the MIMO channel capacity. Therefore the two have to be taken...
This paper offers a study on Rayleigh channel capacity of opportunistic cooperative networks in conjunction with adaptive transmission where the source adapts its rate and/or power level according to the changing channel conditions while the best relay simply amplifies and forwards the signals. To this end, the upper and lower bound of the end-to-end effective signal-to-noise ratio (SNR) for an arbitrary...
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