Showing papers on "Co-channel interference published in 2017"

Kriging-Based Interference Power Constraint: Integrated Design of the Radio Environment Map and Transmission Power

Abstract: This paper proposes a probabilistic interference constraint method with a radio environment map (REM) for spatial spectrum sharing. The REM stores the spatial distribution of the average received signal power. We can optimize the accuracy of the measurement-based REM using the Kriging interpolation. Although several researchers have maintained a continuous interest in improving the accuracy of the REM, sufficient study has not been done to actually explore the interference constraint considering the estimation error. The proposed method uses ordinary Kriging interpolation for the spectrum cartography. According to the predicted distribution of the estimation error, the allowable interference power to the primary user is approximately formulated. Numerical results show that the proposed method can achieve the probabilistic interference constraint asymptotically. Additionally, we compare the performance of the proposed technique with three methods: the perfect estimation, the path loss-based method, and the Kriging-based method without the error prediction. The comparison results show that the proposed method has a higher spectrum sharing opportunity than the path loss-based method, even if only a small amount of measurement data is available. It is also shown that the proposed method dramatically improves the outage probability of the interference power compared to the conventional Kriging-based method.

Theoretical Limits on Multiuser Molecular Communication in Internet of Nano-Bio Things

Abstract: In nano-bio networks, multiple transmitter–receiver pairs will operate in the same medium. Both inter-symbol interference and multi-user interference can cause saturation at the receiver side, and this effect may cause an outage. Thus, we propose a tractable framework to calculate the theoretical operating points for fully absorbing receiver.

Dynamic Spectrum Allocation Scheme for Heterogeneous Network

Abstract: Recently, femtocells (HeNBs) are deployed in heterogeneous network (HetNets) attributable to the addition of coverage, capacity and impeccable spectrum efficiency in private buildings/office complexes surroundings. This unplanned placement of HeNBs creates co-channel interference (CCI) in orthogonal frequency division multiple access (OFDMA). As a result service, disruption occurred at the macrocell user and femtocell user. Therefore, with always expanding interest for frequency spectrum, there is have to make available more resource allocation in order to permit more quantities of unlicensed clients to transmit their signals in the authorized groups. Cognitive-based approaches may increase the spectrum efficiency by sharing resources opportunistically from unlicensed/licensed network. However, spectrum management processes quite difficult, and a lot of chance to occur interference at the cell-edge users. Therefore, a dynamic spectrum allocation scheme is proposed for OFDMA based HetNets. The proposed scheme efficiently reduces the interferences through subchannel detection. To accomplish the CCI mitigation, the proposed scheme is functioning using the energy exposure with group creation algorithm for subchannel detection. Finally, the detected subchannel is allocated through applying power allocation algorithm. The simulation results represent that proposed scheme is able to maximize the spectrum detection and enhanced the spectral efficiency. The improved spectral efficiency recuperates the CCI situation at underlay HetNets.

Retrospective Interference Alignment: Degrees of Freedom Scaling With Distributed Transmitters

Abstract: In this paper, we consider the $K$ -user single-input single-output interference channel with delayed channel state information at the transmitters (CSIT). Our main contribution is to show that even with delayed CSIT and distributed transmitters, the achievable degrees of freedom (DoFs) still scale with the number of users. More specifically, we propose a method that achieves $K/(2\sqrt {K} - 1) \geq \sqrt {K}/2$ DoF. The main idea behind the proposed method is to use interference alignment (IA) at the receiver side in conjunction with repetition coding at the transmitters. Repetition coding repeats the data $R$ times while IA makes the interference generated by a given transmitter identical: 1) at all non-intended receivers and 2) all transmission repetitions. Therefore, one retransmission per transmitter is sufficient to cancel all the interference. This reduces significantly the overhead required for interference removal since the number of interference terms is reduced from $RK(K-1)$ to $K$ .

A new look at AF two-way relaying networks: energy harvesting architecture and impact of co-channel interference

Abstract: In this paper, the performance of dual-hop amplify-and-forward (AF) two-way relaying systems is considered, where the terminals and relay are interfered by a finite number of co-channel interferers. In addition, the derived expressions are evaluated in terms of outage probability and throughput in delay-limited transmission mode. To make the analysis mathematically tractable, the unique expressions of outage probability are adopted to deal with energy harvesting protocols related to time switching and power splitting coefficients and expression of the throughput is also calculated. Based on the analytic results, this paper investigates the impact of system parameters such as energy harvesting time/power fractions, number of interferers and signal-to-noise ratio (SNR) on throughput performance. Monte Carlo simulation results are presented to prove the tightness of the proposed energy harvesting two-way relaying system.

A Taylor Series Approximation of Self-Interference Channel in Full-Duplex Radios

Abstract: The fundamental problem in the design of a full-duplex radio is the cancellation of the self-interference (SI) signal generated by the transmitter. Current techniques for suppressing SI rely on generating a copy of the SI signal and subtracting it partly in the radio frequency (RF) and digital domains. A critical step in replicating the self-interference is the estimation of the multipath channel through which the transmitted signal propagates to the antenna. Since there is no prior model on the number of multipath reflections, current techniques assume a tap delay line filter (in the RF and digital domain) with a large number of taps, and estimate the taps in the analog and the digital domain. In this paper, using a linearization technique, we show that the self-interference channel in an indoor environment can be effectively modeled as $H(f)=C_{0} - C_{1}f$ in the frequency domain. Thus, the effective self-interference channel can be represented by two parameters $C_{0}$ and $C_{1}$ , irrespective of the multipath environment. We also provide experimental evidence to verify the above channel model and propose novel low-complexity designs for self-interference cancellation.

MIMO Full-Duplex Relaying in the Presence of Co-Channel Interference

Abstract: This paper studies the deployment of multiple-input multiple-output (MIMO) full-duplex (FD) relaying systems in a multicell environment, where the source and destination nodes are equipped with a single antenna and communicating via a dual-hop amplify-and-forward (AF) relay station with multiple receive and transmit antennas in the presence of co-channel interference (CCI). This paper addresses the fundamental challenges of loopback self-interference (LI) and CCI when incorporating FD relaying in cellular systems. Due to the higher frequency reuse in FD relaying compared to its half-duplex (HD) relaying counterpart, the CCI is expected to double as the FD relay station simultaneously schedule uplink and downlink transmission on the same channel. The optimal design of relay receive and transmit precoding weight vectors, which maximizes the overall signal-to-interference-plus-noise ratio (SINR) is formulated by a proper optimization problem, and then, a closed-form suboptimal solution based on null space projection is proposed. The proposed precoding vectors are based on the added receive and transmit zero-forcing (ZF) constraints used to suppress the CCI and LI, respectively. To this end, exact closed-form expressions for the outage probability and ergodic capacity are derived, where simpler lower bound expressions are also presented. In addition, the asymptotic high signal-to-noise ratio (SNR) outage probability approximation is also considered, through which the diversity order of the null space projection (ZF/ZF) scheme is found to achieve $\mathrm{min}(N_{R}-M,\, N_{T}-1)$ , where $N_{R}$ and $N_{T}$ are the number of relay receive and transmit antennas, respectively, and $M$ is the number of CCI interferers. Numerical results sustained by Monte Carlo simulations show the exactness of the proposed analytical expressions, as well as the tightness of the proposed lower bound expressions. In addition, simulation results for the minimum mean square error (MMSE)/ZF scheme is also considered for comparison purposes. Our results reveal that MIMO FD relaying could substantially boost the system performance, compared to its conventional MIMO HD relaying counterpart.

Distributed Learning for Energy-Efficient Resource Management in Self-Organizing Heterogeneous Networks

Abstract: In heterogeneous networks, a dense deployment of base stations (BSs) leads to increased total energy consumption, and, consequently, increased cochannel interference (CCI). In this paper, to deal with this problem, self-organizing mechanisms are proposed, for joint channel and power allocation procedures, which are performed in a fully distributed manner. A dynamic channel allocation mechanism is proposed, in which the problem is modeled as a noncooperative game, and a no-regret learning algorithm is applied for solving the game. In order to improve the accuracy and reduce the effect of shadowing, we propose another channel allocation algorithm executed at each user equipment (UE). In this algorithm, each UE reports the channel with minimum CCI to its associated BS. Then, the BS selects its channel based on these received reports. To combat the energy consumption problem, BSs choose their transmission power by employing an on – off switching scheme. Simulation results show that the proposed mechanism, which is based on the second proposed channel allocation algorithm and combined with the on–off switching scheme, balances load among BSs. Furthermore, it yields significant performance gains up to about $40.3\%$ , $44.8\%$ , and $70.6\%$ in terms of average energy consumption, UE's rate, and BS's load, respectively, compared to a benchmark based on an interference-aware dynamic channel allocation algorithm.

Co-channel interference management using eICIC/FeICIC with coordinated scheduling for the coexistence of PS-LTE and LTE-R networks

Abstract: In the Republic of Korea, a Long Term Evolution (LTE)-based public safety (PS)-LTE network is being built using 718~728 MHz for uplink and 773~783 MHz for downlink. However, the same bands are also assigned to the LTE-based high-speed railway (LTE-R) network, so great concerns and practical researches on co-channel interference (CCI) management schemes are urgently required. In this paper, performance is analyzed and evaluated by considering the cases of non-RAN (radio access network) sharing and LTE-R RAN sharing by PS-LTE user equipments (UE). Since a train control signal requires high reliability and low latency in order to fulfill its mission-critical service (MCS) requirements, we give higher priority to LTE-R UE during resource allocation under the LTE-R RAN sharing by PS-LTE UEs. In addition, interference management schemes are more effective for the coexistence of PS-LTE and LTE-R networks under RAN sharing environment. In this paper, we utilize enhanced inter-cell interference coordination (eICIC) and further enhanced ICIC (FeICIC) schemes to mitigate the interference from PS-LTE network to LTE-R network while improving the LTE-R eNodeB (eNB) resource utilization by offloading more PS-LTE UEs to LTE-R network. Moreover, a coordinated multipoint (CoMP) transmission scheme is considered among LTE-R eNBs to enhance LTE-R cell edge user performance. By employing FeICIC along with coordinated scheduling (CS) CoMP, the best throughput performance can be achieved under the case of RAN sharing.

An Efficient Narrowband Interference Suppression Approach in Ultra-Wideband Receiver

Abstract: Ultra-wideband (UWB) radio will be sharing the propagation environment with other pre-existing wireless systems, some possibly creating UWB multiple access interference, and others creating narrowband interference in the UWB radio bands. The Federal Communications Commission regulations have set conditions that limit the interference from the UWB radiators to other wireless systems, however, the issue of eliminating interference to the UWB radios from the pre-narrow band interference existing system is left to the ingenuity of the UWB radio designer. To optimize the performance of UWB wireless communication systems deteriorated by strong narrowband interferences, a high-efficiency interference suppression scheme is proposed in this paper. The closed-form weight coefficient iteration expression of basic adaptive notch filter cell with two constrained zero-pole pairs is derived. For multiple narrowband interferences case, a high-order cascaded adaptive interference suppression scheme is also presented. The simulation result demonstrates that the proposed narrowband interference suppression approach has excellent suppression effects to narrowband interferences in UWB systems, since a significant signal to noise ratio improvement is obtained. In addition, the proposed narrowband interference suppression algorithm is particularly fit for low-cost UWB wireless reception connected with Rake combining techniques.

Mitigation Techniques to Reduce the Vulnerability of Railway Signaling to Radiated Intentional EMI Emitted From a Train

Abstract: This paper evaluates several techniques capable of mitigating the impact of low-power radio frequency jammers that interfere with ground-to-train communications. These radio communications are used for railway signaling, and interfering with these signals can have a negative impact on the train operation. Although the commercialization, detention, and use of radiofrequency jammers is strictly forbidden in most countries, they can be easily found on the internet at low cost and unexpectedly switched on by a passenger in a moving train. In this paper, we evaluate and compare the ground-to-train radio communication and intentional electromagnetic interference (IEMI) received signal powers delivered by roof train antennas to the train control command receiver. This comparison is used to deduce the potential zones of interference along the train trajectory and its consequences. Operating at the physical layer, we then propose and evaluate three mitigations techniques that can be used separately or combined to reduce the impact of this type of interference. We show that they can significantly reduce the jamming capability and help us in maintaining railway full operation.

Side Lobe Suppression in NC-OFDM Systems Using Variable Cancellation Basis Function

Abstract: In non-continuous orthogonal frequency division multiplexing (NC-OFDM)-based cognitive radio system, the sidelobe suppression methods use the fixed length rectangular windowing functions for canceling carriers (CCs) like the extended active interference cancellation (EAIC) and active interference cancellation (AIC) methods. The AIC and its EAIC methods reduce the interference a lot, but the CCs in different frequency have a non-uniform assignment for sidelobe suppression. To overcome this problem a novel variable basis function proposed in which the CCs are grouped by frequency positions and modeled with different waveforms of different length to suppress NC-OFDM side lobes effectively while reducing inter carrier interference (ICI) at the same time. Simulation results show that using variable basis functions of the proposed method, −60-dB sidelobe suppression depth is reached even with higher order 64-QAM symbol mapping and the ICI caused by the subcarriers is almost negligible.

Enabling Technologies toward Fully LTE-Compatible Full-Duplex Radio

Abstract: Full-duplex radio has potential to double spectral efficiency by simultaneously transmitting and receiving signals in the same frequency band, but at the expense of additional hardware and power consumption for self-interference cancellation. Hence, the deployment of a full-duplex cellular network can be realized by employing full-duplex functionality only at an eNodeB, which is supposed to have sufficient computation and power resources, and by scheduling pairs of half-duplex UEs that are in either downlink or uplink. By doing so, fast and smooth full-duplex deployment is possible while minimally affecting the legacy UEs and the rest of the network entities. In this article, we provide technical challenges and solutions for an LTE-compatible full-duplex cellular network, featuring wideband and wide dynamic range support for RF self-interference cancellation, and robust and efficient self-interference channel estimation for digital self-interference cancellation. Based on a realistic LTE-based cellular model, our full-duplex radio design is evaluated through system-level simulations and real-world testbed experiments. Simulation results show that a significant throughput gain can be achieved by the full-duplex technique despite the existence of physical limiting factors such as path loss, fading, and other-cell interference. Testbed measurements reveal that at a bandwidth of 20 MHz, self-interference cancellation up to 37 dB is achieved in the RF domain, and most of the residual self-interference is further cancelled down to the noise floor in the subsequent digital domain.

Analytical Framework for Space Shift Keying MIMO Systems With Hardware Impairments and Co-Channel Interference

Abstract: This letter provides a general analytical framework for multiple-input multiple-output space shift keying systems considering hardware impairments, at the transmitter and receiver sides, and co-channel interference. Specifically, a closed-form expression for the average bit error probability (ABEP) in the case of two transmit antennas and arbitrary number of receive antennas is derived. As well, a tight upper bound ABEP expression in the general case of arbitrary number of transmit and receive antennas is obtained. Besides, an asymptotic simple expression is found over Rayleigh fading channels. Analytical results, which are validated via simulation ones, explicitly demonstrate that non-zero bounds of the ABEP exist in the high power region, which is in contrast to the case of ideal hardware, where the ABEP asymptotically goes to zero.

Blind Analog Interference Cancellation

Abstract: A blind solution to analog interference cancellation is proposed for scenarios where the interference source is known at the receiver. Beyond conventional solutions, the proposed interference cancellation scheme has two merits: 1) it is implemented with analog signal processing, which is suitable for the systems with extremely strong interference and 2) it does not need any training process for adjusting parameters of analog devices, which reduces the computational complexity and time delay. For the purpose of performance evaluation, the power spectral density expressions are formulated in closed form for the desired signal and the interference components after the proposed blind interference cancellation. Furthermore, illustrative numerical results not only substantiate the outstanding performance of the proposed scheme, specifically in the case of strong interference, but also provide useful principles for the pulse shaping filter design in the transceiver.

SAS PAL GAA co-channel interference mitigation

Abstract: A shared spectrum network device in a higher-tier network may include one or more processors configured to receive information provided from a lower-tier network, estimate, based on the information, interference to the higher-tier network from one or more transmitters of the lower-tier network, compare the estimated interference to a threshold value, and identify a geographic zone in which transmission by one or more transmitters of the lower-tier network is limited based on the comparison.

Empowering Device-to-Device Networks with Cross-Link Interference Management

Abstract: Device-to-device (D2D) communications is an emerging service model that is currently under standardization by 3GPP. While D2D offloading has a great potential to relieve increasingly congested cellular networks, its benefits, however, come at a cost, namely interference. Most of the prevailing D2D designs conservatively avoid interference via either spectrum resource allocation or power control. These designs, however, do not exploit spatial degrees of freedom (DoF), which are inherently supported by multi-antenna devices. In this work, we present $\sf {MD2D}$ , a multiuser D2D system that embraces concurrent D2D transmissions, while leveraging MIMO techniques to actively eliminate interference across D2D pairs. $\sf{MD2D}$ has a systematic methodology that checks whether the antenna combination in a D2D network is capable of eliminating cross-pair interference and, thereby, ensuring interference-free concurrent transmissions. If the interference can be eliminated, then $\sf{MD2D}$ applies a bucket-based DoF assignment algorithm to determine an effective antenna usage configuration that handles the interference. We evaluate our design via testbed experiments and large-scale simulations. The results show that, as compared to the traditional interference avoidance scheme, $\sf{MD2D}$ improves the throughput by 87.39 and 218.84 percent in a three-pair testbed and in large-scale simulations, respectively.

Performance analysis of ant colony based optimization algorithm in MIMO systems

Abstract: In a multi MIMO system, various signals are transmitted concurrently within the identical frequency band. It can effect on considerable enhancements in spectral efficiency as well as system capacity. This paper employs MIMO system to overcome the challenges for receiver design. The signal obtained at the base station or access point, faces co channel interference and inter-symbol interference. In this paper an ant colony optimization method supported by soft iterative detection mechanism for BPSK modulated signals is presented. It uses basic MAP conditions to select the most likely signals from the search space. This process results in configuration of the receiver is such a way that it can remain functioning under overloaded and critically loaded situations. The experimental outcome outperforms the existing methods in terms of iterations, Bit Error Rate, Signal to Noise Ratio and capacity.

An Experimental-Based Analysis of Inter-BAN Co-Channel Interference Using the $\kappa$ - $\mu$ Fading Model

Abstract: In this communication, we empirically study and model the impact of co-channel interference and background noise (BN) on a body area network (BAN) operating at 2.48 GHz using the extremely generalized κ-μ fading model. The BAN measurements considered three nodes with the signal-of-interest (SoI) forming the link between two wearable devices located on the front-central-chest and front-centralwaist of an adult male, while an interfering signal emanated from a third wearable device that was located on the front-central-waist of an adult female. Three environments were considered which are indicative of different environmental multipath conditions likely to be encountered by everyday BAN users, namely, an anechoic chamber, a reverberation chamber and an indoor laboratory. As well as this, the influence of different human mobility scenarios was studied. Utilizing the κ and μ parameter estimates, we then provide some useful insights into the outage performance of BAN systems in the presence of BN when both the SoI and the interferer undergo κ-μ fading.

Relay-Aided Successive Aligned Interference Cancellation for Wireless $X$ Networks With Full-Duplex Relays

Abstract: This paper proposes a novel relay-aided successive aligned interference cancellation (RaSAIC) method for a $\text{2}\times K$ $X$ channel with $L$ full-duplex relays, each of which is fully connected to the channel. The core idea of the RaSAIC is to apply a cooperative relays' precoding technique that aligns interference signals at unintended receivers while creating an Alamouti structure for the desired signals. With the proposed cooperative relay transmission technique, it is shown that both the optimal sum degree of freedom (sum-DoF) gain of $\text{2}K/(K+\text{1})$ and the diversity gain of two are achievable for both constant and time-varying channels when the numbers of relays' antennas are enough to meet the derived conditions, without requiring channel state information (CSI) at transmitters, but with global CSI at relays. Furthermore, it is demonstrated that the same sum-DoF and diversity gain are attainable, even in the presence of interrelay interference due to a full-duplex relaying operation if the memory at the relay nodes is exploited in the proposed manner.

Random cognitive radio network performance in Rayleigh-lognormal environment

Abstract: Recently, considerable research has been focused on the design of random cognitive radio networks because base stations are randomly located in modern cellular networks and also because of an anticipated shortage of spectrum. This study investigates the performance of cognitive radio networks using a stochastic geometry approach in Rayleigh-lognormal fading. We present a geometric model of cognitive radio networks where primary transmitters, primary receivers, secondary transmitters, and secondary receivers are distributed as a Poisson point process. We analytically derive the coverage probability and transmission rate of that network. Moreover, we obtain closed-form expressions of coverage probability and transmission rate. We then numerically evaluate coverage probability and transmission rate performance. It is shown that for the coverage probability and transmission rate, the results are better for lower densities of primary transmitters and secondary transmitters.

Co-channel interference cancellation using constraint field of view ADR in VLC channel

Abstract: A constraint field of view angular diversity receiver (CFOV-ADR) is proposed in VLC systems which can completely eliminate the co-channel interference (CCI) from neighborer transmitters and significantly reduce the inter-symbol interference (ISI) from multipath reflections The results show the superior performance over conventional ADR

Outage analysis in two-way communication with RF energy harvesting relay and co-channel interference

Abstract: The study of relays with the scope of energy harvesting (EH) looks interesting as a means of enabling sustainable, wireless communication without the need to recharge or replace the battery driving the relays. However, the reliability of such communication systems becomes an important design challenge when such relays scavenge energy from the information bearing radio-frequency signals received from the source, using the technique of simultaneous wireless information and power transfer (SWIPT). To this aim, this work studies bidirectional communication in a decode-and-forward (DF) relay–assisted cooperative wireless network in the presence of co-channel interference (CCI). In order to quantify the reliability of the bidirectional communication systems, a closed-form expression for the outage probability of the system is derived for both power splitting (PS) and time switching (TS) modes of operation of the relay. Simulation results are used to validate the accuracy of our analytical results and illustrate the dependence of the outage probability on various system parameters, like PS factor, TS factor and distance of the relay from both of the users. The results of performance comparison between PS relaying (PSR) and TS relaying (TSR) schemes are also presented. Besides, simulation results are also used to illustrate the spectral efficiency and the energy efficiency of the proposed system. The results show that, in terms of both spectral efficiency and energy efficiency, the two-way communication system in the presence of moderate CCI power, performs better than the similar system without CCI. Additionally, it is also found that PSR is superior to TSR protocol in terms of peak energy efficiency.

Carrier Sensing for OFDMA-Based D2D Group-Casting Systems

Abstract: Device-to-device (D2D) communications refer to direct communications between two or more devices without transferring data through the base station or other infrastructure. For synchronous D2D communication systems in most recent researches and development, orthogonal frequency-division multiple access (OFDMA) or single-carrier frequency-division multiple access (SC-FDMA) is considered to increase the communication coverage and to maintain the similarity with the cellular communication systems. One important design consideration for OFDMA-based (or SC-FDMA-based) D2D communication systems, particularly in an ad-hoc network mode, is the in-band emission effect, which corresponds to the mutual interference between different signals over other subchannels in the same time slot. To avoid interference from other transmitters or to other receivers, a transmitter may perform carrier sensing, which allows for transmission only when the measured interference is below the given threshold. Since the characteristics of the performance degradation due to other-channel interference (OCI) can be quite different from those by cochannel interference (CCI), the interference measurement must be carefully considered for carrier sensing in OFDMA-based D2D communication systems. This paper discusses physical carrier sensing for interference management in D2D group-casting or broadcasting systems and proposes a mechanism that efficiently avoids the interference from other subchannels. More specifically, outage probability is derived by taking both OCI and CCI into account and is then employed as a reference for the carrier sensing level in the course of selecting the resource blocks (RBs) for D2D communication. We demonstrate that our proposed carrier sensing scheme can significantly increase the areal capacity subject to the given target outage performance.

Software defined radios as cognitive relays for satellite ground stations incurring terrestrial interference

Abstract: Satellite to ground links are extremely vulnerable to any type of terrestrial interference due to the relatively weak satellite signal at the ground stations. This can cause connection failures or degradation in performance at the ground station, which could in some cases be significant or even catastrophic. The great flexibility of software defined radio (SDR) systems facilitates the implementation of cognitive relays as a complementary entity that can help reduce the effects of interference. In this paper, we describe a cognitive SDR testbed that has been developed based on the Universal Software Radio Peripheral (USRP) and the GNU radio software platform. One of our testbed's aims is to evaluate error performance improvements of satellite signal relays in the presence of interference. We report on performance evaluation in terms of bit error ratio (BER) as a function of carrier-to-noise ratio (CNR) and in the presence of interference, for our detect and relay algorithms in an example frequency band, using an emulated desired (satellite-relay-ground station) signal. Our testbed contains four separate segments: satellite (emulated), relay, interferer, and ground receiver. At each segment, we transmit and/or receive signals via SDRs or standard communication laboratory equipment. We consider two relaying protocols in our work, amplify-and-forward (AF), and decode-and-forward (DF). Initial experiments were indoors, although outdoor testing with small unmanned aircraft systems is planned for future work. Our experiments explore the effects of different relaying techniques, and provide some quantitative results on performance improvements via our software defined radio approach.

Capacity Results for the Multicast Cognitive Interference Channel

Abstract: The capacity region of the multicast Cognitive Inter-Ference Channel (CIFC) is investigated. This channel consists of two independent transmitters that wish to multicast two different messages, each to a different set of users. In addition, one of the transmitters—commonly referred to as the cognitive transmitter—has prior non-causal knowledge of both messages to be transmitted. This scenario subsumes some long-standing open problems, such as the interference channel , the broadcast channel , and multicast communications . The aim of this paper is the derivation of optimal interference mitigation techniques under different interference regimes. To this end, two settings, namely the multi-primary CIFC , i.e., $M=1$ and $N \geq 1$ , and its complementary, the multi-secondary CIFC , i.e., $N=1$ and $M \geq 1$ , are investigated as an attempt to build a thorough understanding for the more general multicast CIFC setting. It is shown that, for some interference regimes, well-known coding techniques for the standard CIFC remain still optimal under the constraint of multicasting to multiple users. However, in other interference regimes, capacity achieving coding and decoding schemes prove to be more involved. A careful combination of these coding schemes and new outer bounding techniques allows to characterize the capacity region for several classes of discrete memoryless and Gaussian multicast CIFC under different interference regimes.

Relay Selection Scheme Based on Quantum Differential Evolution Algorithm in Relay Networks

Abstract: It is a classical integer optimization difficulty to design an optimal selection scheme in cooperative relay networks considering co-channel interference (CCI). In this paper, we solve single-objective and multi-objective relay selection problem. For the single-objective relay selection problem, in order to attain optimal system performance of cooperative relay network, a novel quantum differential evolutionary algorithm (QDEA) is proposed to resolve the optimization difficulty of optimal relay selection, and the proposed optimal relay selection scheme is called as optimal relay selection based on quantum differential evolutionary algorithm (QDEA). The proposed QDEA combines the advantages of quantum computing theory and differential evolutionary algorithm (DEA) to improve exploring and exploiting potency of DEA. So QDEA has the capability to find the optimal relay selection scheme in cooperative relay networks. For the multi-objective relay selection problem, we propose a novel non-dominated sorting quantum differential evolutionary algorithm (NSQDEA) to solve the relay selection problem which considers two objectives. Simulation results indicate that the proposed relay selection scheme based on QDEA is superior to other intelligent relay selection schemes based on differential evolutionary algorithm, artificial bee colony optimization and quantum bee colony optimization in terms of convergence speed and accuracy for the single-objective relay selection problem. Meanwhile, the simulation results also show that the proposed relay selection scheme based on NSQDEA has a good performance on multi-objective relay selection.

Frequency-Domain Intergroup Interference Coordination for V2V Communications

Abstract: With the development of vehicle-to-vehicle (V2V) communications, the interference among different V2V communication groups will become the limitation for high-rate transmissions. Two intergroup interference coordination schemes are proposed for the V2V communication. The first proposed scheme is a Doppler-shift-based frequency-domain interference alignment scheme. Through pre- and postprocessing, we guarantee that one V2V group is free from interference, and the other V2V group is partially interfered. The second proposed scheme is a frequency-domain precoding scheme. Through frequency-domain precoding, the intergroup interference between the two V2V groups can be mitigated completely.

GNSS interference monitoring and characterisation station

Abstract: An interference monitoring station is presented which detects, characterises and logs interference events. The system operates autonomously and continuously over multiple global navigation satellite system (GNSS) bands. With a bandwidth of up to 80 MHz, input resolution of 8 bit an overall data rate of approximately 1.3 Gbit/s can be supported. The interference detection is carried out in real-time, while the interference characterisation is executed in post-processing. The characterisation is separated in temporal and signal contents, as this allows both continuous wave (CW) and pulsed signals to be analysed independently of their frequency dynamics. This approach of characterisation has also proven to allow a broader spectrum of interferences to be classified. Examples of real-world events are presented.

Performance analysis of multiantenna two-way relay network with co-channel interference

Abstract: This paper presents the performance analysis of the multiple antenna two-way amplify and-forward (AF) relay network in an interference-limited environment. Multiple antenna system is considered to overcome the fading effect. To avoid the high feedback overhead and fully exploit multiple antenna diversity, we employ transmit antenna selection (TAS) at the user node and analog network coding (ANC) at relaying node. We are assuming the presence of multiple co-channel interference (CCI) at the AF relay and noisy sources, an approximate closed-form expression for the overall outage probability (OOP) is derived. To gain more insight into system performance high SNR analysis is done and asymptotic expression for OOP is obtained. Furthermore, upper bound on ergodic capacity (EC) and approximate expression for symbol error probability(SEP) are derived. The tightness of our analysis is attested through Monte Carlo simulation and provides the insight into the impact of CCI under the general operating conditions and the key system parameters on overall system performance.