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This paper examines a type of linear beamforming for communications in interference networks. First, a receiver beamformer design is derived from a Maximum Likelihood (ML) framework with Automatic Gain Control (AGC) constraints. The studied beamformer keeps the complexity of the receiver low and it is able either to remove full coherent arrivals or to enhance them when required when different AGC...
The general two-user memoryless multiple-access channel, with common channel state information known to the encoders, has no single-letter solution which explicitly characterizes its capacity region. In this paper a binary “dirty” multiple-access channel (MAC) with “common interference”, when the interference sequence is known to both encoders, is considered. We determine its sum-capacity, which equals...
The spectrum sharing game and the quality of its equilibria have been widely studied in a variety of contexts. In this paper we consider two pairs of communicating users that share two bands of spectrum. Through the analysis of the Nash equilibria, we provide the conditions, with respect to the normalized signal and interference strengths, for the set of equilibria power allocations to coincide with...
Secrecy on the physical layer receives increased research interest. Especially in the wireless communication scenarios, the interest in confidentiality of messages increases. In this paper, we discuss the effectiveness of the beamforming strategies maximum ratio transmission (MRT), zero forcing (ZF), and an optimized beamforming (BF) strategy for the transmission under secrecy constraints. The applied...
Treating the interference as noise, the paper studies the first derivative of the frontiers which trace the achievable rates region of the 2-user interference channel. The achievable rates region in this case was found to be the convex hull of the union of two regions, each is bounded by a log-defined line. Those log-defined lines are characterized by holding one of the transmitters at full power,...
We consider a two-user symmetric gaussian interference channel (IC), in which one encoder is connected to the other by a unidirectional orthogonal cooperative link with specific capacity. In this setup, we employ a simplified Han-Kobayashi scheme along with cooperative communication. We characterize the generalized degrees of freedom of the channel for interference-limited regimes by comparing the...
It is known that the capacity of parallel (multi-carrier) Gaussian point-to-point, multiple access and broadcast channels can be achieved by separate encoding for each subchannel (carrier) subject to a power allocation across carriers. In this paper we show that such a separation does not apply to parallel Gaussian interference channels in general. A counter-example is provided in the form of a 3...
The spectrum sharing problem between heterogeneous networks that are not interoperable is considered. Two strategies for interference management are studied. First, by treating the possible interference from adjacent transmitters as noise, each transmitter can achieve a certain information rate which merely depends upon the channel quality, but does not depend upon the burstiness of packets arrival...
This paper studies interference channels with security constraints. The existence of an external eavesdropper in a two-user interference channel is assumed, where the network users would like to secure their messages from the external eavesdropper. The cooperative binning and channel prefixing scheme is proposed for this system model which allows users to cooperatively add randomness to the channel...
In most communication system, multiple users need to be supported. In OFDM systems, multiple access is achieved through combining TDMA and FDMA. OFDM supports multiusers with popular multiple access schemes, these schemes are MC - CDMA and OFDMA. In this paper we propose a precoding based approach to multiple access in OFDM systems using singular value decomposition (SVD). The scheme is like a CDMA...
In this paper we discuss performance results of a novel real-time closed-loop power amplifier (PA) linearization technique that has originally been proposed by Ahmed and Li. The novel approach performs on-the-fly prediction and measurement of the PA AM/AM and AM/PM non-linearity, stores such non-linear characteristics and calculates their inverse functions in order to pre-distort the base-band amplitude...
Ultra-wideband (UWB) systems possess several distinct features such as very high data rate, large multipath or frequency diversity and improved ranging precision while requiring low-power low-complexity transceivers. Among the different modulation schemes, differential PSK is an attractive option because it does not require channel estimation, and hence reduces implementation complexity. This paper...
This paper discusses the performance of the wavelet based filtered multi-tone (WFMT) modulation. The novel WFMT modulation was proposed in 2003 for improving characteristics of wireless and DSL multicarrier systems. In this paper we describe a main idea of WFMT and discuss the advantages of this novel modulation. The WFMT modulation in comparison with OFDM and DMT has low level of out-of-band side...
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