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Multicell coordinated beamforming, where multiple base stations (BSs) collaborate with each other in the beam-vectors design to mitigate the intercell interference (ICI), has been a subject of great attention recently. With perfect channel information available at the base stations, we first present a fast converging algorithm that solves the weighted sum rate maximization (WSRM) problem. Then, the...
While in-home and access technologies are located at different places in the end-to-end communication chain, they have been shown to mutually interfere. In this contribution, we quantify the mutual impact of an in-home network and a Digital Subscriber Line access link. Both regular and vectored VDSL2 links are considered. For newer in-home technologies, which are able to use a large bandwidth, the...
High Altitude Platform System (HAPS) is an exceptional technology in aerial communications systems. Some inimitable facets of HAPS compose it as a spectacular service provider. However, interference with other aerial or terrestrial communications systems is a significant issue. With regards to system interference as of other commercial products or systems which perform partially at the same frequency...
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...
Radio interference drastically affects the performance of sensor-net communications, leading to packet loss and reduced energy-efficiency. As an increasing number of wireless devices operates on the same ISM frequencies, there is a strong need for understanding and debugging the performance of existing sensornet protocols under interference. Doing so requires a low-cost flexible testbed infrastructure...
Number of indoor Wireless Sensor Network (WSN) applications are increasing day by day. However, there are many interferers (like 802.11 × and 802.15.4 devices) effecting 2.4 GHz band. Moreover, co-existence is a bigger challenge for WSNs because of their tiny structure and resource constraints. In this paper, a novel method is proposed to predict the near future channel quality using the statistical...
Urban environments are notorious for their high spectrum usage, particularly in their unlicensed radio bands. Wireless sensor network (WSN) nodes incorporate modern transceivers that can measure the background noise/interference and change channels. These combined capabilities suggest the need to better understand urban environments so that nodes can better avoid competing devices. In this paper,...
In this paper, we formulate a joint optimization problem for resource allocation and scheduling in multi-cell orthogonal frequency division multiple access (OFDMA) half-duplex decode-and-forward (DF) relay assisted networks. Our problem formulation takes into account multi-cell interference and heterogeneous data rate requirements. We transform the resulting non-convex and combinatorial optimization...
We consider the performance of underwater acoustic ad-hoc networks in the presence of interference. We assume a uniform distribution of nodes over a finite area. The node-to-node channel is modeled using frequency dependent path loss and Ricean fading. We adopt a communication theoretic approach and study the interdependence of the sustainable number of hops through the network, end-to-end frame error...
Frequency agility is considered as an indispensable feature of next-generation wireless sensor networks (WSNs), which will have to cope with highly interfered environments due to the increasing diffusion of wireless devices operating in unlicensed bands. In this paper we investigate some design aspects related to spectrum sensing in “cognitive” WSNs, relating the duration of sensing time to the probability...
Secondary users (SUs) should have power constraints because primary users (PUs) should not be interfered by SUs in cognitive radio (CR) network. Therefore it is important for SUs to maximize throughput and ensure quality of service (QoS) on the premise of generating no interference to PUs. In this paper, SUs are equipped with multiple antennas. Multiple-input multiple-output (MIMO) wireless communication...
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...
It is known that in a cognitive random wireless network, the aggregate interference from secondary network is not Gaussian. Using Shannon's bound for the capacity of general additive channels, Gaussian interference/noise is the worst case due to its maximum entropy property which leads to minimum capacity. Therefore, it is favorable to have the distribution of interference as far from Gaussian as...
In this paper, we consider a cognitive radio network in which the secondary users are allowed to share the spectrum with the primary users as long as the interference caused by the secondary users to the primary users is below a specified level. Both the primary users and secondary users access the common channel by way of transmission schedules. The channel model includes realistic features such...
This paper presents our design of a cognitive beamforming array that can be used for communications and RF mapping. This novel approach is through joint frequency and spatial scan to establish both spatial and spectral knowledge of the local environment. With this information, we are able to establish the optimal frequencies and beam patterns to exploit the current environmental situation, including...
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...
Spectrum sharing is promising to improve the efficiency of spectrum usage. However, this technology may incur severe narrow band interference (NBI), which seriously complicates the synchronization problem. This paper investigates the timing synchronization problem in the presence of NBI for the OFDM-based spectrum sharing systems. We consider the cross-correlation based timing synchronization and...
Interference can be a major impediment to the operational performance of radar systems. A common source of interference is impulsive noise which may appear due to regional lighting discharges or local man-made noise sources. Impulsive noise is characterized as having a large amplitude and short duration and therefore only affects a small portion of the time series. Unpredictable frequency distortion...
This paper presents an iterative Maximum Likelihood Decoding (MLD) scheme for Multiple Input Multiple Output (MIMO) systems using Space-Time Block Codes (STBC) in strong directional interference scenario. The proposed scheme avoids matrix-inversion computation needed in ordinary reception schemes and estimates noise-subspace-projected channel matrix instead of real channel matrix to perform decoding...
This paper presents an outdoor-to-aircraft measurement campaign conducted inside a long range Airbus A340-300 aircraft in order to evaluate the attenuation induced by the haul of the aircraft. The obtained results can be used to perform an interference study and assess whether the aircraft on-board network interferes to the terrestrial links. The minimum aircraft attenuation was found 15.5 dB. This...
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