The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The paper discusses the problem of location a mobile cellular terminal within an urban, multipath-rich environment, using available geographical information such as terrain and building maps. The method suggested in the paper is the use of ray tracing in order to characterize the propagation environment. The paper focuses on single antenna location, namely a trilateration — based algorithm and suggests...
Deterministic network calculus (DNC) is not suitable for deriving performance guarantees for wireless networks due to their inherently random behaviors. In this paper, we develop a method for Quality of Service (QoS) analysis of wireless channels subject to Rayleigh fading based on stochastic network calculus. We provide closed-form stochastic service curve for the Rayleigh fading channel. With this...
In coding theory, concatenated codes form a class of error-correcting codes that are derived by combining an inner code with an outer code. This is a solution to the problem of finding a code that has both exponentially decreasing error probability with increasing block length and polynomial-time decoding complexity. The work presented in this paper, provides link level performance analysis of non-line...
This paper presents a novel technique to save the transmitting power of spread-spectrum communication systems based on the application of delay diversity. The core idea of this delay-diversity system is to delay two spreading sequences that carry the same information of a bit with respect to each other in order to statistically separate the influence of fading on the same bit in time domain. The theoretical...
Communication between two neighboring nodes is the most basic operation in wireless networks. Yet very little research has focused on the local delay, defined as the mean time it takes a node to connect to a nearby neighbor. This problem is non-trivial when link distances are random but static, as is the case when the node distribution of a static network is modeled as a stochastic point process....
In this work, we investigate secret key generation from channel states. We point out, by means of a packet-delay-based attack, that observing its own channel states is not the only way an adversary can learn about the channel states of the legitimate communicating parties. The attack suggests that it is not secure to transmit data via the channel whose states generate secret keys. However, not using...
Orthogonal frequency division multiplexing (OFDM) systems have enjoyed widespread adoption in high data rate wired and wireless networks, due to their ability to efficiently cope with slowly varying dispersive channels. This paper considers the information theoretic secrecy rates that are achievable by an OFDM transmitter/receiver pair in the presence of an eavesdropper that might either use an OFDM...
In mobile radio communications there is an ever-increasing demand for high speed and high quality data transmission. Error correction and multi-channel reception are two promising techniques incorporated in the present-day cellular system to attain high-quality and high-speed communication is a multipath fading environment where the rapid variations of the channel gain degrades the transmission quality...
We study the outage diversity of the multiple-input multiple-output (MIMO) Rayleigh block-fading channel when causal channel state information (CSI) is available at the transmitter (CSIT). Within this setting, we consider the optimal power allocation for blocks b = 1, ..., B given perfect CSIT for blocks 1, ..., b-u only, subject to a long-term power constraint. The parameter 0 ≤ u ≤ B is a fixed...
This paper presents a new technique for multipath detection in wideband mobile radio systems. An intelligent search algorithm using Boolean Satisfiability (SAT) techniques is used to search for the multipath delays. The proposed algorithm finds the multipath components with high probability and hence allows the system to utilize the inherent diversity in these components to mitigate channel fading...
We analyze the outage probability of frequency domain minimum mean squared error turbo equalization over frequency-selective Rayleigh fading channels with exponential delay power profile. A correlation chart analysis is used to evaluate the convergence property of the iterative system. Based on the convergence characteristic of the equalizer and decoder, we derive a closed form approximation to the...
In this paper, we develop a method for analyzing time-varying wireless channels in the context of the modern theory of the stochastic network calculus. In particular, our technique is applicable to channels that can be modeled as Markov chains, which is the case of channels subject to Rayleigh fading. Our approach relies on theoretical results on the convergence time of reversible Markov processes...
The error rate performance of a previously developed reduced complexity channel estimator, known as the generalized least mean squares (GLMS) algorithm, is investigated in conjunction with a minimum-mean-square-error (MMSE) decision feedback equalizer (DFE). The channel estimator is based on the theory of polynomial prediction and Taylor series expansion of the underlying channel model in time domain...
In this paper, the performance of phase hop diversity in multiple input multiple output (MIMO) wireless system is researched. We get the diversity order of the phase hop diversity (PHD) according to the definition of diversity order and discuss the diversity order in different cases. Although diversity order is an important parameter to evaluate the performance of a communication system using diversity,...
Slotted Aloha is an effective random access protocol and can also be an important element of more advanced media access protocols. This paper investigates slotted Aloha in a cognitive radio environment where one access point provides services for both primary users and secondary users. Considering packet capture effects in a Rayleigh fading channel, we present the mathematic derivations of system...
A low-complexity hardware implementation method is proposed for discrete-time frequency-selective Rayleigh fading channels. The proposed method first employs the sum-of-sinusoids method to generate multiple independent flat fading channel responses, then utilizes a simple weight-delay-sum filtering method to incorporate the fractionally-delayed multipath rays into inter-tap correlated tap gains. It...
We consider packet transmission policies in the cross-layer perspective that minimize the average power consumed by the transmitter under the average delay constraints. We present a simple packet scheduling policy which is influenced by both the queue and the channel state and that can be utilized to trade-off characteristic between queueing delay and transmission power policy. The near-optimal scheduler...
We propose an optimum power allocation scheme for distributed antenna systems (DAS) in time-varying Rayleigh and Ricean fading channels. In the conventional power allocation schemes for DAS, channel state information (CSI) for feedback includes the fast small-scale fading. This causes two practical problems. First, tracking fast fading requires considerable extra bandwidth and processing, which becomes...
During the last decade, many works were devoted to improving the performance of relaying techniques in ad hoc networks. One promising approach consists in allowing the relay nodes to cooperate, thus using spatial diversity to increase the capacity of the system. However, this approach introduces an overhead in terms of information exchange, increasing the complexity of the receivers. A simpler way...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.