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.
This work is inspired by the question "Can 100 speakers talk for 30 minutes each in one room within one hour and with zero interference to each other's audience?" posed by Cadambe and Jafar at the 45th Allerton conference 2007. We consider the problem of how many transmitter-receiver pairs can be placed such that each desired link may use half of the channel time free of interference from...
The problem of network coding over a multiple-access channel (MAC) is considered in this paper. Lattice strategies of encoding indexes of messages are proposed, ensuring that if the sum of any two lattice points is another point over a finite field, then the sum of the two indexes mapped to these two points is equal to the index mapped to another point. In this way, the interference caused by other...
Switching transients generated by a selection diversity combiner corrupt receiver filters and increase the system outage as well as corrupting channel estimation. In order to produce an accurate (transient-free) channel estimate and reduce the internal outage, one prefers small switching rates. Therefore, knowledge of the switching rate provides useful information for system engineers in the design...
An efficient encoder circuit for a systematic Reed-Solomon code with arbitrary parity positions is presented. In contrast to the Reed-Solomon encoder circuits widely available today, the parity symbols produced by this encoder are not restricted to form a block of consecutive parity symbols at the beginning or end of the codeword, but may be spread arbitrarily within the codeword. A general structure...
In this paper, a novel general small-scale fading model for wireless communications, that describes the nonhomogeneous nature of the propagation medium, is introduced. Its probability density function (PDF) is given by a simple, exact, and closed-form expression. Namely, the η - λ - μ includes the λ - μ, the η - μ, the gamma, the exponential, the Hoyt, the Nakagami-m, the Rayleigh, and the one-sided...
In this paper, we derive the maximum likelihood (ML) channel estimate in the presence of phase noise (PHN) and I/Q imbalance for OFDM systems. Since it is estimated jointly with I/Q and PHN, the channel estimate is more robust to these RF impairments compared to the conventional schemes. The complexity of the joint estimator is reduced using an approximate cost functions for both PHN and I/Q imbalance...
This paper proposes the distributed space-time block code (D-STBC) over frequency selective fading channel that achieves both spatial diversity gain and low decoding complexity with decoupling property in amplify-and-forward (AF) relay networks. These two goals are simultaneously achieved by our proposed code design, where the source permutates and conjugates the transmitted data before sending to...
Unlike most IEEE 802.11-based ad hoc networks, in which only a single channel is used, wireless mesh networks allow the simultaneous use of multiple channels to increase the aggregated capacity. Many efforts have been taken to better exploit multiple non-overlapped channels. Although the IEEE 802.11 b/g standards, which govern the unlicensed 2.4 GHz industrial, scientific and medical (ISM) band, provide...
This paper deals with the problem of estimating the average signal-to-noise ratio (SNR) for a communication system employing non-coherent binary frequency shift keying (NCBFSK) over fading channels with white Gaussian noise (AWGN). The maximum likelihood (ML) estimator and one using data statistics have been derived and simulated for various scenarios including data-aided (DA), non-data aided (NDA)...
In wireless MIMO ad-hoc networks, channel reciprocity is assumed to optimize transmit and receive beamformers in conventional beamforming algorithms. But, when channels between nodes are not reciprocal, it is a huge burden to the feedback channel to inform a transmitting node of the channel state information. In this paper, we propose a distributed beamforming scheme with limited feedback for non-reciprocal...
A novel distribution referred to as N*generalized K, constructed as the product of N statistically independent, but not necessarily identically distributed, generalized K random variables (RVs) is introduced. Statistical characterization of the proposed distribution is carried out via the derivation of closed-form expressions for its moment generating, probability density, cumulative distribution...
In this paper we consider an interference-free multi-beamforming protocol for multi-source multi-destination relay networks. The new protocol adopts the amplify and forward policy as its cooperative transmission strategy and adjusts the weights of relays to realize an improved multi-pair source-destination data transfer. We in particular investigate the issue how to choose the weights of relays to...
The IMP distortion occurring with the amplification of OFDM signals through a nonlinear RF power amplifier (PA) is analysed with a view to establishing internal relations and impairment significance of different types and combinations - composition categories- of IMPS. Through this, a novel estimation method was deduced to calculate power spectral densities (PSD) of nonlinear distortion. This method...
High peak-to-average power ratio (PAPR) of the transmitted signals is a major drawback of orthogonal frequency division multiple access (OFDMA) systems. The selected mapping (SLM) method is one of the major schemes employed for PAPR reduction. Unfortunately, the computational complexity of traditional SLM scheme is relatively high since a number of inverse fast Fourier transforms (IFFTs) are required...
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.