278 results
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2. A New Proof for the DoF Region of the MIMO Networks With No CSIT.
- Author
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Rassouli, Borzoo, Hao, Chenxi, and Clerckx, Bruno
- Abstract
In this paper, a new proof for the degrees of freedom (DoF) region of the $K$-user multiple-input multiple-output (MIMO) broadcast channel (BC) with no channel state information at the transmitter (CSIT) and perfect channel state information at the receivers (CSIR) is provided. Based on this proof, the capacity region of a certain class of MIMO BC with channel distribution information at the transmitter (CDIT) and perfect CSIR is derived. Finally, an outer bound for the DoF region of the $K$-user MIMO interference channel (IC) with no CSIT is provided. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
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3. Distance Estimation Schemes for Diffusion Based Molecular Communication Systems.
- Author
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Wang, Xiayang, Higgins, Matthew D., and Leeson, Mark S.
- Abstract
Molecule concentration is often used as the information carrier to accomplish diffusion-based molecular communications (DMC) among nano-machines. To achieve the optimal functionality, knowing the distance between the transmitter nano-machine (TN) and the receiver nano-machine (RN) is of high importance. In this paper, two distance estimation schemes are proposed based upon the RN-sensed concentration which changes with regards to the time and distance. The RN estimates the distance by means of measuring either the concentration-peak time or received concentration energy. Simulations are performed to compare the accuracy of each scheme and to discover how the diffusion channel and noise may influence the accuracy. Results show that both schemes will provide a beneficial enhancement to molecular communication systems. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
4. A Novel Scrambler Design for Enhancing Secrecy Transmission Based On Polar Code.
- Author
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Sayed, Mostafa Ahmed Mohamed, Liu, Rongke, and Zhang, Chenyu
- Abstract
Scrambling is a way of enhancing physical layer security presented in many papers. However, few of these papers have mentioned the scrambling effect on the polar coding secrecy. In this letter, we introduce a new scrambling module combined with a polar coding system, in which pre-assigned key is unnecessary. The presented scrambling module combines linear and nonlinear structure. The presented linear structure increases the branch number in a low-complexity way to enhance algorithm diffusion power, and the nonlinear part can resist the differential attack and reduces the mutual information between its input and output. With the proposed module, the bit channels, which are good for Bob and Eve, can also be applied to transmit secret message, making transmission rate of the secret massage configurable. Simulation results show that our method can guarantee the secrecy transmission between Alice and Bob. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
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5. Time-Domain Oversampled OFDM Communication in Doubly-Selective Underwater Acoustic Channels.
- Author
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Peng, Bo, Salvo Rossi, Pierluigi, Dong, Hefeng, and Kansanen, Kimmo
- Abstract
This paper investigates the time-domain oversampled cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) system for communication over doubly-selective underwater acoustic channels. Channel estimation is based on two different time-varying channel models. One is the basis expansion model (BEM), the other is the Doppler-rate model (DRM). Exploiting the sparsity of underwater acoustic channels, orthogonal matching pursuit (OMP) is employed to obtain the time-varying channel state information (CSI). The receiver operates without any prior knowledge of the statistics of the CSI, as this information usually is unavailable for underwater acoustic channels. Channel estimation error and bit error rate (BER) performance of the system are demonstrated through numerical simulations. Results show that the oversampled CP-OFDM achieves significant gains over the conventional symbol-rate sampled system. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
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6. A Spectrum Efficient Multi-User Transmission Scheme for 5G Systems With Low Complexity.
- Author
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Jin, Huangping, Peng, Kewu, and Song, Jian
- Abstract
To maximize the system throughput for downlink multi-user transmission considering fairness among the users, superposition coding (SC) with all the users scheduled simultaneously is optimal. But it would also lead to high implementation complexity at receivers. In this paper, a simplified downlink multi-user transmission scheme is proposed via combining SC and time division multiplexing (TDM). All the users are divided into multiple user groups and only the users within each user group are scheduled simultaneously via SC. Closed-form expression for the system throughput by the proposed scheme is derived and numerical results are provided to demonstrate the difference in the system throughputs by the proposed scheme and the optimal SC as well as TDM. With the proposed scheme, a good tradeoff between performance and complexity can be achieved. It is shown that the proposed scheme can reduce the implementation complexity considerably at the cost of a little system throughput loss. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
7. Novel Frequency-Domain Oversampling Receiver for CP MC-CDMA Systems.
- Author
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Yan, Yanxin and Ma, Maode
- Abstract
The multi-carrier code division multiple access (MC-CDMA) technique is a promising technology because it incorporates the benefits of the orthogonal frequency division multiplexing (OFDM) and the direct sequence code division multiple access (DS-CDMA) techniques. The bit error rate (BER) of the MC-CDMA system reduces more quickly than that of the OFDM system when increasing the transmission power. In this paper, we propose a novel frequency-domain oversampling (FDO) minimum mean square error (MMSE) receiver for the cyclic prefix (CP) MC-CDMA. Simulation results show that the proposed FDO based receiver for the CP MC-CDMA systems can outperform the traditional zero forcing (ZF) and MMSE equalizers in terms of BER performance for all the spreading factors (SF). [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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8. An Iterative DFE Receiver for MIMO SC-FDMA Uplink.
- Author
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Dhivagar, B., Kuchi, Kiran, and Giridhar, K.
- Abstract
Ever since the adoption of the single carrier frequency division multiple access (SC-FDMA) scheme for the uplink in the Long Term Evolution (LTE) standard, there has been much interest in improved receiver algorithms for the same. Successive interference cancelation (SIC) based turbo receivers (Turbo SIC) have been proposed to tackle the multi-stream interference (MSI) for transmission modes such as spatial multiplexing (SM) and multiuser (MU) multiple input multiple output (MIMO). In addition, decision feedback equalizers (DFE) have been discussed as an alternative to the simple linear minimum mean square error (LMMSE) based receivers to suppress intersymbol interference (ISI) caused by the frequency selective multi-path channel. This paper proposes a DFE receiver variant based on parallel interference cancelation (PIC) with maximum likelihood detection (MLD) and ordered SIC (OSIC) principles to suppress ISI and MSI. Simulations show that the proposed receiver performs better than the existing SIC and DFE based receivers and achieves the matched filter bound (MFB) for both coded and uncoded systems. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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9. Resource Allocation for Cooperative LTE-Advanced Uplink.
- Author
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Karimi, Ali and Sabbaghian, Maryam
- Abstract
In this paper, we develop joint power allocation, sub-carrier pairing and relay selection strategies to maximize the capacity of single carrier frequency division multiple access (SC-FDMA) systems. The problem is investigated in the framework of a dual-hop amplify-and-forward network where power allocation is performed only in the relay node. In this work, we prove the optimality of ordered sub-carrier pairing (OSP) and reverse OSP (ROSP) for receivers with frequency domain equalizers based on minimum mean square error (MMSE) and zero forcing (ZF), respectively. We obtain significant improvement by the proposed joint resource allocation strategies. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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10. Frequency-Domain NOMA With Two Sets of Orthogonal Signal Waveforms.
- Author
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Maatouk, Ali, Caliskan, Ersoy, Koca, Mutlu, Assaad, Mohamad, Gui, Guan, and Sari, Hikmet
- Abstract
We present a non-orthogonal multiple access (NOMA) scheme based on combining orthogonal frequency-division multiple access and multi-carrier code-division multiple access. Contrary to other NOMA architectures, the proposed approach does not require any power imbalance between user signals, making it possible to grant all users the same data rate and performance. Another major contribution concerns the receiver operation: Many papers in the recent NOMA literature refer to single-stage successive interference cancellation, where the strong user signal is first detected and subtracted from the received signal before detecting the weak user signal. While this approach may be optimal from information theoretic viewpoint, we show that this type of receiver cannot achieve performance results close to those of interference-free transmission and that, in our framework, an iterative receiver is actually required for this purpose. We investigate both hard-decision and soft-decision iterative receivers and show that a soft-decision receiver significantly improves the performance and increases the number of users. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
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11. A Novel Low Complexity Faster-Than-Nyquist Signaling Detector Based on the Primal-Dual Predictor-Corrector Interior Point Method.
- Author
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Ibrahim, Ahmed, Bedeer, Ebrahim, and Yanikomeroglu, Halim
- Abstract
Faster-than-Nyquist signaling (FTNS) is a promising non-orthogonal physical layer transmission technique to improve the spectral efficiency of next-generation communication systems but at the expense of increased transciever complexity to remove the artificially introduced intersymbol-interference (ISI). In this paper, we investigate the detection problem of FTNS and propose a low-complexity sub-optimal detection algorithm, stemming in operations research, that is based on convex relaxation, primal-dual predictor-corrector interior point method, and quantization. The proposed convex quadratic relax-and-quantize sequence estimation (CQRAQSE) algorithm is suitable for low rates FTNS and demonstrates an excellent trade-off between the detection performance and computational effort. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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12. High Speed WDM VLC System Based on Multi-Band CAP64 With Weighted Pre-Equalization and Modified CMMA Based Post-Equalization.
- Author
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Yiguang Wang, Li Tao, Yuanquan Wang, and Nan Chi
- Abstract
Multi-user access is one of the key problems in the visible light communication (VLC). In this paper, we propose and experimentally demonstrate an approach for multi-user access based on multi-band CAP modulation over a wavelength division multiplexing (WDM) VLC system using a single RGB LED. In this scenario each wavelength will provide 3 sub-bands. Depending on the combination of the different wavelength and the sub-bands, a dynamic capacity can be achieved for up to 9 users access. At the transmitter a weighted pre-equalization method is proposed to overcome frequency attenuation of the LED, while at the receiver a post-equalizer based on modified cascaded multi-modulus algorithm (CMMA) is utilized. The experimental results show that the bit error rate (BER) for an over-all 1.35 Gb/s CAP64 signal over 30-cm transmission can be under the 7% forward error correction (FEC) limit of 3.8 × 10-3. The results clearly demonstrate the benefit and feasibility of the multi-band CAP modulation for the short range multi-user VLC systems. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
13. An OFDM-Based Waveform With High Spectral Efficiency.
- Author
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Conceicao, Filipe, Gomes, Marco, Silva, Vitor, and Dinis, Rui
- Abstract
A new Time Interleaved Block Windowed Burst OFDM (TIBWB-OFDM) transceiver scheme is studied in this paper, where adjacent OFDM sub-blocks are allowed to overlap in time. This leads to a smaller overall block, increasing the spectral efficiency and decreasing the peak-to-average power ratio (PAPR) of the transmitted signals, when compared with standard TIBWB-OFDM. These efficiency gains are obtained at the expense of interference between sub-blocks, which deteriorates the performance. Thus, we propose several receiver embodiments that include frequency domain equalizers and time domain interference cancellation algorithms to cope with channel effects and interference introduced by the overlapping operation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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14. Improving Non-Orthogonal Multiple Access by Forming Relaying Broadcast Channels.
- Author
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So, Jungho and Sung, Youngchul
- Abstract
In this letter, the performance of non-orthogonal multiple access (NOMA) with full-duplex relaying is investigated in multi-user single-input single-output downlink systems. Contrary to the original NOMA, in the proposed NOMA scheme, the base station (BS) and two served receivers within a resource block form a relaying broadcast channel (RBC), where one of the two receivers serves as a relay as well as a receiver. To analyze the performance of the proposed scheme, a simple achievable rate region of an RBC with compress-and-forward (CF) relaying is newly derived based on the noisy network coding (NNC). Furthermore, based on this, an achievable rate region of an RBC with NNC relaying when dirty-paper coding (DPC) is applied at the BS is derived. Numerical results show that the NOMA equipped with the proposed combined coding scheme comprised of DPC and NNC relaying yields significant gain over the originally proposed NOMA. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
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15. High-Security Chaotic Cognitive Radio System With Subcarrier Shifting.
- Author
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Lu, Huaiyin, Zhang, Lin, Jiang, Ming, and Wu, Zhiqiang
- Abstract
Chaotic sequences have been applied to cognitive radio (CR) systems to enhance the system security. However, since the chaotic maps are publicly known, attackers may derive the key parameters of chaotic sequences, then finally retrieve the information. In this paper, we present a new subcarrier-shifting based chaotic cognitive radio (SSCCR) scheme for improving the security mechanism of chaotic cognitive radio (CCR) systems. More specifically, we propose to transmit the information with the chaos-subcarrier pair by combining the chaotic sequence with available subcarriers, where the chaos-subcarrier pairs dynamically change with shifted subcarriers. The subcarrier shifting rule is determined by another chaotic sequence for security enhancement. With the developed mathematical model, we analytically derive its bit error rate (BER) formula. Simulation results are compared to verify the effectiveness of our derivations, and the information leakages of SSCCR and CCR systems are studied. It is demonstrated that the proposed SSCCR system offers a high security and the malicious attackers can not retrieve the transmitted information even if they get the key chaos parameters. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
16. Data Enriched SACK: A Novel Acknowledgement Generation Scheme for Secure SCTP.
- Author
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Kumar, V. Anil and Das, Debabrata
- Abstract
The Stream Control Transmission Protocol (SCTP) is inherently vulnerable to optimistic Selective Acknowledgement (SACK) spoofing. We highlight a threat scenario in which this vulnerability is exploited for the generation of sustained and powerful Denial-of-Service attack flood over the Internet. We identify and analyze a fundamental design limitation in SCTP that leads to the above mentioned vulnerability and propose a novel acknowledgement generation scheme, called Data Enriched SACK (DESACK), to make SCTP robust against optimistic SACK spoofing. We present the design and implementation details of DESACK. The proposed scheme is experimentally implemented, tested and integrated into the SCTP framework in the Linux Kernel. We also provide real-world experimental results to demonstrate the feasibility and effectiveness of DESACK on a highly loaded multi-hop production network. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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17. Joint Data and Energy Transmission in a Two-Hop Network With Multiple Relays.
- Author
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Tang, Lan, Zhang, Xinggan, and Wang, Xiaodong
- Abstract
Wireless energy transfer (WET) is a promising technique to prolong the lifetime of an energy-constrained wireless network. In this paper, we consider a two-hop communication system with multiple relay nodes powered by WET. To minimize the transmission time, we propose an optimal transmission scheme, in which the relay nodes adopt a “harvest-then-decode and forward” policy. The optimal transmission time allocation of the source and each relay node is calculated by a linear program under causality constraints on both data and energy arrivals. The analytical and simulation results reveal the relationship between the optimal time allocation and system parameters. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
- View/download PDF
18. Optimal Index Codes for a New Class of Interlinked Cycle Structure.
- Author
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Vaddi, Mahesh Babu and Rajan, B. Sundar
- Abstract
The interlinked cycle (IC) structure that generalizes cycles and cliques was defined by Thapa, Ong, and Johnson. Interlinked-cycle-cover (ICC) scheme that leverages IC structures in digraphs to construct scalar linear index codes was proposed. A class of infinitely many digraphs, where the proposed scalar linear codes based on ICC scheme are optimal were characterized by Thapa et. al. In this paper, we provide an addition to this class by providing optimal length index codes for IC structures with one cycle among non-inner vertex set. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
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19. Joint Wireless Information and Power Transfer for an Autonomous Multiple Antenna Relay System.
- Author
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Huang, Yang and Clerckx, Bruno
- Abstract
Considering a three-node multiple antenna relay system, this letter proposes a two-phase amplify-and-forward (AF) relaying protocol, which enables the autonomous relay to simultaneously harvest wireless power from the source information signal and from an energy signal conveyed by the destination. We first study this energy-flow-assisted (EFA) relaying in a single-input single-output (SISO) relay system and aim at maximizing the rate. By transforming the optimization problem into an equivalent convex form, a global optimum can be found. We then extend the protocol to a multiple antenna relay system. The relay processing matrix is optimized to maximize the rate. The optimization problem can be efficiently solved by eigenvalue decomposition, after linear algebra manipulation. It is observed that the benefits of the energy flow are interestingly shown only in the multiple antenna case, and it is revealed that the received information signal and the energy leakage at the relay can be nearly separated by making use of the signal space, such that the desired signal can be amplified with a larger coefficient. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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20. The Cognitive Interference Channel With a Causal Relay in Very Strong Interference.
- Author
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Reategui, Fernando, Imran, Muhammad Ali, and Tafazolli, Rahim
- Abstract
We study the cognitive interference channel where an additional node (a relay) is present. In our model the relay's operation is causal rather than strictly causal, i.e., the relay's transmit symbol depends not only on its past but also on its current received symbol. We derive outer bounds for the discrete and Gaussian cases in very strong interference. A scheme for achievability based on instantaneous amplify-and-forward relaying is proposed for this model. The inner and outer bounds coincide for a special case of very strong interference. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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21. Secrecy Rate Maximization With Artificial-Noise-Aided Beamforming for MISO Wiretap Channels Under Secrecy Outage Constraint.
- Author
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Wang, Bo, Mu, Pengcheng, and Li, Zongze
- Abstract
The secrecy rate maximization with the artificial noise (AN) aided beamforming for the multipel-input-single-output (MISO) wiretap channel is addressed in this paper under the constraint of secrecy outage probability. The channel state information (CSI) of the main channel is assumed to be perfectly known while the CSI of the eavesdropper is modeled as a complex Gaussian random vector. The generalized AN scheme where the AN is not constrained to be orthogonal to the information-bearing signal is considered. The complete solution to the maximum achievable secrecy rate and the corresponding optimal power allocation between the information-bearing signal and the AN is obtained without making any approximation of the secrecy outage probability constraint. The result shows that the optimal AN is always orthogonal to the information-bearing signal. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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22. Robust Transceiver Design Based on Joint Signal and Interference Alignment for MIMO Interference Channels With Imperfect Channel Knowledge.
- Author
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Kim, Myeong-Jin, Lee, Hyun-Ho, and Ko, Young-Chai
- Abstract
In this letter, we propose a new transceiver design based on joint signal and interference alignment, which provides the robustness against imperfect channel knowledge in multiple-input multiple-output (MIMO) interference channels. Under the assumption of norm-bounded channel uncertainties, the proposed robust transceiver design minimizes the interference signals that leak outside the interference subspace and makes the desired signal fall into the orthogonal complement of the interference subspace. From simulation results, we demonstrate that our proposed robust transceiver design offers not only better sum rate performance but also higher robustness against imperfect channel knowledge than the conventional scheme. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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23. Generalized Reduced-State Vector Sequence Detection.
- Author
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Satchidanandan, Bharadwaj, Kuchi, Kiran, and Koilpillai, R. David
- Abstract
A multi-dimensional set-partitioning scheme is proposed for joint reduced-state sequence detection (JRSSD) of vector sequences corrupted by intersymbol interference (ISI) and additive white Gaussian noise (AWGN). The existing multi-dimensional set-partitioning schemes result in complexity exponential in the dimensionality of the vectors in the vector sequence. The proposed set-partitioning scheme allows the construction of reduced-state trellises with very few states even when the vectors are of high dimensionality. One of the key requirements of the JRSSD algorithm is an efficient algorithm for spatial multi-symbol detection, for which we propose the reduced-state tree (RST) detection algorithm. In addition to performance improvement, the inclusion of RST algorithm for spatial multi-symbol detection provides a common framework for designing receivers for both flat-fading and frequency-selective fading MIMO channels. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
- Full Text
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24. Timing Estimation Based on Higher Order Cyclostationarity for Faster-Than-Nyquist Signals.
- Author
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Lopez Morales, Manuel Jose, Roque, Damien, and Benammar, Meryem
- Abstract
Faster-than-Nyquist (FTN) transmission is a promising technique to increase the spectral efficiency at a fixed constellation size. However, traditional timing synchronization algorithms mostly rely on the eye diagram opening after matched-filtering (e.g., Gardner and zero-crossing). Such approaches are, thus, unsuitable in the presence of the FTN-induced intersymbol interference. In this letter, we first show that FTN signals exhibit cyclostationarity at the $l$ th order ($l > 2$) according to their bandwidth and symbol period. Then, we derive non-data-aided timing offset estimators from the cyclic temporal cumulant function. Besides its relevance for strong FTN scenarios, the proposed solution is also robust to frequency and phase offsets. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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25. Beam Tracking Under Highly Nonlinear Mobile Millimeter-Wave Channel.
- Author
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Lim, Jaechan, Park, Hyung-Min, and Hong, Daehyoung
- Abstract
We propose approaches to the problem of multi-paths beam tracking in millimeter-wave (mmWave) mobile communications. Precise angle tracking is necessary to take advantage of beamforming technology in this mmWave band. The mobile channel is a highly nonlinear function with respect to the state that comprises the beam angle and the channel path gain. Therefore, the beam angle tracking is challenging and crucial. We propose a couple of particle filtering frameworks for beam tracking and show outperforming result of an auxiliary particle filtering approach over recently proposed tracking approaches. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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26. Novel OFDM System Using Data-Nulling Superimposed Pilots With Subcarrier Index Modulation.
- Author
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Wang, Qingbo, Dou, Gaoqi, He, Xianwen, Deng, Ran, and Gao, Jun
- Abstract
A novel orthogonal frequency-division multiplexing system using data-nulling superimposed pilots with subcarrier index modulation (SIM) is proposed, where the constellation modulation vector is first spread over all subcarriers using a precoding matrix, then the subcarriers activated by SIM are nulled and inserted by the superimposed pilots (SPs). As the nonzero subcarriers index of the SP is exploited to convey additional information using SIM, the SP not only completes channel estimation without a loss of bandwidth, but also transmits additional information. Two different blind pilot-detection techniques (BPDTs) (which detects the nonzero subcarriers index of the SP without any prior knowledge at the receiver) are designed to demodulate the information conveyed by the SP using SIM and extract the SP from the received signal to estimate channel state information. Monte Carlo simulation results show that the proposed BPDTs achieve good pilot detection performances, and the nonzero subcarrier index of the SP is effectively exploited to convey additional information. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
27. Multistatic Radar Placement Optimization for Cooperative Radar-Communication Systems.
- Author
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Ben Kilani, Moez, Gagnon, Ghyslain, and Gagnon, Francois
- Abstract
In this letter, we investigate a scenario where both multistatic radar and point-to-point communication systems are present with a partial or total spectrum-sharing constraint. We propose a new adaptive radar receivers placement mechanism that jointly maximizes the signal-to-interference-plus noise ratio of each communication transmitter–radar receiver channel while minimizing the geometric dilution of precision. The proposed joint approach performs well in the presence of communication interference on the radar side. In fact, the proposed approach helps to increase the capability to properly demodulate the communication data at each radar receiver resulting in the less radar measurement errors due to communication interference while enhancing the target positioning accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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28. Blind CFO Estimation in OFDMA Uplink Transmission With General Carrier Assignment Scheme.
- Author
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Wang, Yen-Chin and Phoong, See-May
- Abstract
Carrier frequency offset (CFO) estimation is a challenging issue in uplink orthogonal frequency division multiple access (OFDMA) systems. Most existing blind estimation methods for these systems are derived under certain types of carrier assignment scheme (CAS). In this letter, we propose a new blind CFO estimation algorithm for uplink OFDMA systems with constant modulus constellation. The proposed estimator can estimate CFO under any type of CAS, with only one antenna at the receiver. Moreover, the proposed method can be applied to OFDMA with or without virtual/null subcarriers. Simulation results show that the proposed estimator performs well under arbitrary CAS. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
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29. MIMO Techniques for Carrierless Amplitude and Phase Modulation in Visible Light Communication.
- Author
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Akande, Kabiru O. and Popoola, Wasiu O.
- Abstract
In this letter, multiple-input multiple-output (MIMO) techniques are proposed to improve the spectral efficiency and bit error rate (BER) performance of the conventional carrierless amplitude and phase modulation (CAP) in visible light communication. Analytic frameworks for both multiplexing and diversity MIMO techniques are developed for CAP. The analytical expressions in line-of-sight (LOS) propagation are validated via simulation. A precoding technique is further applied to improve the power efficiency of the multiplexing scheme resulting in a signal-to-noise ratio (SNR) gain of 28.5 dB. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
30. Impact of LoRa Imperfect Orthogonality: Analysis of Link-Level Performance.
- Author
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Croce, Daniele, Gucciardo, Michele, Mangione, Stefano, Santaromita, Giuseppe, and Tinnirello, Ilenia
- Abstract
In this letter, we focus on the evaluation of link-level performance of LoRa technology, in the usual network scenario with a central gateway and high-density deployment of end-devices. LoRa technology achieves wide coverage areas, low power consumption and robustness to interference thanks to a chirp spread-spectrum modulation, in which chirps modulated with different spreading factors (SFs) are quasi-orthogonal. We focus on the performance analysis of a single receiver in presence of collisions. First, we analyze LoRa modulation numerically and show that collisions between packets modulated with different SFs can indeed cause packet loss if the interference power received is strong enough. Second, we validate such findings in experiments based on commercial devices and software-defined radios. Contradicting the common belief that SFs can be considered orthogonal, our results demonstrate that inter-SF collisions are indeed an issue in LoRa networks and, thus, allocating higher SFs to users far from the gateway might not necessarily improve their link capacity, in case of congested networks. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
31. Throughput Analysis of Power-Beacon-Assisted Energy Harvesting Wireless Systems Over Non-Identical Nakagami- m Fading Channels.
- Author
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Le, Ngoc Phuc
- Abstract
We consider a distributed power-beacon (PB)-assisted wireless powered communication network that consists of multiple PBs, multiple transmitters, and one receiver. The transmitters harvest energy from the PBs, and then transmit their individual data to the receiver via time division multiple access. Fading coefficients of channels between nodes are assumed independent but not necessarily identically distributed Nakagami- m random variables. We derive an exact expression for the achievable throughput. A closed-form approximated expression of the throughput in the high signal-to-noise ratio regime is obtained. Moreover, we proposed the optimal time allocation method to maximizing the sum throughput of the whole system. Our analysis is corroborated by Monte Carlo simulations. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
32. Impulse Noise Mitigation in IR-UWB Communication Using Signal Cluster Sparsity.
- Author
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Sharma, Sanjeev, Gupta, Anubha, and Bhatia, Vimal
- Abstract
In this letter, we propose a novel robust impulse radio-ultra-wide band (IR-UWB) receiver design that utilizes the received UWB signal cluster sparsity characteristics to mitigate impulse noise (IN). The IN samples are easily detected and removed in the proposed receiver. Furthermore, multiple UWB signal clusters (due to multipath channel), in the proposed receiver design, reduce UWB signal blanking loss as compared with the single cluster (single path channel). The proposed receiver’s bit error rate (BER) performance is theoretically analyzed and compared with six popular existing non-linear receivers in the presence of IN over standardized IEEE 802.15.4a channel models. Unlike the existing receivers, the proposed receiver does not require a priori knowledge of the amplitude, the probability of occurrence of IN, or channel estimation. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
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33. A Novel Quasi Orthogonal Space Frequency Code For Cooperative Communication.
- Author
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Zeng, Rong and Liu, Tianjing
- Abstract
A novel quasi orthogonal space-frequency block coding (QOSFBC) orthogonal frequency division multiplexing (QOSFBC-OFDM) scheme for doubly selective channels is proposed, which adopts the time difference of arrival (TDOA) parameter to calculate the complex phase rotation factor utilized in the pre-coding matrix. The novel QOSFBC employed in centralized cooperative scheme can obtain 3.056 diversity gain and full transmission rate at 15 dB SNR. Furthermore, the impact of TDOA on the performance of QOSFBC-OFDM system is investigated in the Rayleigh fading channels. Simulation results show that the proposed quasi-orthogonal recovering QOSFBC (QOR-QOSFBC) can achieve at most 12 dB more SNR gain after demodulation than the conventional QOSFBC. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
34. Aggregation-Assisted Combining for MIMO Multiple ARQ Systems.
- Author
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Park, Sangjoon
- Abstract
This letter proposes an aggregation-assisted combining (AAC) for multiple-input multiple-output multiple automatic repeat request systems. The proposed AAC can be considered as a hybrid scheme of the symbol-level combining (SLC) and bit-level combining (BLC), which consists of the aggregation-assisted log-likelihood ratio (LLR) calculation and subsequent LLR combining stages. The aggregation-assisted LLR calculation stage is performed in a similar manner on the SLC except that the interference-to-noise reformulation is performed instead of the terminated-packet elimination; thus, the remaining interference from the terminated packets is regarded as additional noise. This additional noise can degrade the LLR quality from the aggregation-assisted LLR calculation stage. Therefore, the proposed AAC combines the currently calculated LLRs with the previously calculated LLRs similar to the BLC when the previously calculated LLRs have less LLR contaminations, i.e., they experience fewer numbers of terminated packets. The simulation results verify that the proposed AAC outperforms the BLC and even achieves a performance comparable with the SLC with simplified reception procedures. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
35. Complete Targets Coverage in Wireless Sensor Networks With Energy Transfer.
- Author
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Yang, Changlin, Chin, Kwan-Wu, Liu, Ying, Zhang, Junbao, and Liu, Jizhao
- Abstract
This letter considers energy harvesting sensor nodes monitoring multiple fixed targets. The goal is to monitor these targets for the longest time period. A key challenge, however, is that sensor nodes have varying energy harvesting rates, meaning that the coverage lifetime of targets is limited by sensor nodes with low energy. To this end, we consider energy sharing between sensor nodes. We model the problem as a mixed integer linear program (MILP). Advantageously, our MILP models non-linear energy conversion rates. We also outline a heuristic for large-scale networks. Our results show energy sharing and non-linear energy conversion rates prolong coverage lifetime. Finally, our heuristic achieves 90% of the optimal coverage lifetime. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
36. Antenna Selection for Energy Efficient MISO Systems.
- Author
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Wang, Zijian and Vandendorpe, Luc
- Abstract
This letter studies the mathematical property of the energy-efficiency (EE) function for multiple-input single-output systems with transmit antenna selection. We prove that the monotonicity of the function is guaranteed if the system signal-to-noise ratio satisfies a sufficient condition, which is quite feasible in practice. Based on this property, an algorithm with low complexity is proposed to find the maximum EE. The monotonicity of the function and the advantage of the proposed algorithm are confirmed by numerical results. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
37. Interference Analysis in Wireless Power Transfer.
- Author
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Chen, Yunfei, da Costa, Daniel B., and Ding, Haiyang
- Abstract
This letter studies the effect of co-channel interference (CCI) generated by wireless power transfer on information delivery for three widely used setups, i.e., power beacon (PB), hybrid access point (HAP), and simultaneous wireless information and power transfer (SWIPT). It focuses on the comparison of CCI from these three schemes in terms of the average interference power, the ergodic capacity, and the bit error rate. Numerical results show that the extra interference caused by wireless power transfer indeed degrades the system performance. Moreover, SWIPT has the largest degradation, while PB and HAP have the same degradation when proper parameters are chosen. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
38. Theoretical Analysis of the Dynamic Decode Ordering SIC Receiver for Uplink NOMA Systems.
- Author
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Gao, Yichen, Xia, Bin, Xiao, Kexin, Chen, Zhiyong, Li, Xiaofan, and Zhang, Sha
- Abstract
Instead of successive interference cancellation (SIC) for uplink non-orthogonal multiple access systems with fixed decoding order based on the statistical channel state information (CSI), we focus on decoding with the dynamic order according to the instantaneous CSI. After modeling the channel fluctuation of all the users with different transmit powers and different path losses, a dynamic SIC receiver is proposed based on the instantaneous received power of different users. The outage probability of the proposed system is theoretically analyzed and the closed-form expressions for a three-user system are derived. Simulations are performed to validate the accuracy of the theoretical results. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
39. GFDM BER Under Synchronization Errors.
- Author
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Gaspar, Danilo, Mendes, Luciano, and Pimenta, Tales
- Abstract
Generalized frequency division multiplexing (GFDM) is a candidate waveform for the air interface of the fifth generation mobile network. In one of the foreseen scenarios for this future network, known as massive machine type communication, the demand for a low power consumption and a loose synchronization scheme might result in residual symbol-time and carrier-frequency offsets. The overall system performance under time and frequency misalignments is crucial in this application scenario. The main aim of this letter is to present an analytical model to evaluate the performance degradation in terms of bit error rate for GFDM when synchronization is not perfect. The analytical results are corroborated with computational simulation BPSK mapping. The agreement between simulation and theoretical curves shows that the model presented in this letter can be used to predict the GFDM bit error rate performance under the presence of synchronization errors. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
40. Molecular Channel Fading Due to Diffusivity Fluctuations.
- Author
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Qiu, Song, Asyhari, Taufiq, Guo, Weisi, Wang, Siyi, Li, Bin, Zhao, Chenglin, and Leeson, Mark
- Abstract
Molecular communications via diffusion is sensitive to environmental changes, such as the diffusion coefficient (mass diffusivity). The diffusivity is directly related to a number of parameters, including the ambient temperature, which varies slowly over time. While molecular noise models have received significant attention, channel fading has not been extensively considered. Using experimental data, we show that the ambient temperature varies approximately according to a normal distribution. As a result, we analytically derive the fading distribution and validate it using numerical simulations. We further derive the joint distribution of the channel gain and the additive noise, and examine the impact of such interactions on the ISI distribution, which is shown to conform to a generalized extreme value distribution. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
41. Joint Dimming Control and Transceiver Design for MIMO-Aided Visible Light Communication.
- Author
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Li, Baolong, Zhang, Rong, Xu, Wei, Zhao, Chunming, and Hanzo, Lajos
- Abstract
The multiple-input multiple-output (MIMO) concept has been readily invoked in visible light communication (VLC) for increasing data rate. In this letter, we conceive a general solution of dimming control and MIMO transceiver design for VLC, which is capable of minimizing the mean-squared error between the transmitted and received signals, while at the same time, maintaining a specific indoor illumination level. We take into consideration practical optical constraints in the design, including the LED non-linearity and the specific dimming requirements. An efficient solution of our design problem is derived by conceiving a projected gradient algorithm. Our numerical results show that the proposed scheme achieves better bit error rate performance as well as significantly higher convergence speed than its benchmarker conceived in 2015. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
42. A Novel Calibration Method of DC-Offsets in Direct-Conversion Transmitter.
- Author
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Zhang, Shengyi, Tian, Yu, Ye, Peng, Guo, Lianping, Zeng, Hao, and Li, Hao
- Abstract
Direct-conversion transmitter based on the zero intermediate frequency architecture has been widely used. However, the direct current offsets (DC-offsets) introduced by the modulator affect the system performance and severely limit the calibration of IQ imbalance errors. This letter focuses on estimating and calibrating DC-offsets of modulators in the transmitter. Based on the frequency difference between the transmitted local oscillator (LO) signal and the received LO signal, the parameters of DC-offsets can be estimated by exploiting a training sequence and a self-closed loop system to achieve digital pre-compensation. The frequency response of the feedback loop and the interference introduced by the receiving channel can be ignored. There is no need to add additional hardware circuits, and the algorithm’s complexity is lower than other methods. In addition, the frequency-independent IQ imbalance errors in the transmit channel are accurately estimated. Finally, the effectiveness of the proposed algorithm is verified by simulation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
43. A New Family of Time-Limited Nyquist Pulses for OFDM Systems.
- Author
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Sharique, Mohd and Chaturvedi, A. K.
- Abstract
We first provide the motivation for a new family of time-limited Nyquist pulses for Orthogonal Frequency Division Multiplexing (OFDM) systems by multiplying existing Nyquist pulses in the frequency domain. The condition required for the resultant pulses to have a roll-off factor less than or equal to unity is then established. The roll-off factor is found to be a function of two design parameters. Thus, once the roll-off factor is fixed, there is an opportunity to optimize the two design parameters, such that the signal-to-interference ratio (SIR) in the presence of carrier frequency offset is maximized. As an illustration, a new pulse is designed by multiplying the time-limited Better Than Raised Cosine and RC pulses in the frequency domain, followed by optimization for SIR maximization. The obtained pulse is compared with a pulse, which is known to provide the best out-of-band (OOB) power performance among the known pulses for OFDM systems. From the comparison, it is clear that the obtained pulse provides better SIR performance while maintaining the same OOB power performance. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
44. Adaptive Relaying Protocol for Wireless Power Transfer and Information Processing.
- Author
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Tao, Ran, Salem, Abdelhamid, and Hamdi, Khairi Ashour
- Abstract
In this letter, an amplify-and-forward (AF) relaying system is considered, where an energy constrained relay node harvests energy from the received radio frequency signal and uses this harvested energy to AF the source signal to the destination. Based on the time switching (TS) and power splitting (PS) receiver architectures, an adaptive receiving architecture for energy harvesting and information processing is proposed and an adaptive relaying (AR) protocol based on it is developed to enable energy harvesting and information processing at the relay. In light of this, analytical expressions of throughput are derived for both delay-limited transmission and delay-tolerant transmission modes, when the AR protocol is implemented at the relay. Monte Carlo simulations are provided throughout to validate our analysis and the impact of some important system parameters on the adopted performance metric are investigated. In addition, we compare the system performance in terms of the throughput of AR protocol with PS relaying and TS relaying protocols proposed by Nasir et al. Results show that, the AR protocol has a better system performance around the point in which there is a throughput crossover for both PS relaying and TS relaying protocols. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
45. On Network Coding for Funnel Networks.
- Author
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Karimian, Pourya, Borujeny, Reza Rafie, and Ardakani, Masoud
- Abstract
Network coding for non-multicast problems has been the subject of many recent studies. In this letter, we consider networks in which the total capacity of the incoming links to each intermediate node is not less than the total capacity of its outgoing links. We call these networks funnel networks and prove that any feasible non-multicast problem on funnel networks is solvable by routing (hence, by linear network coding, too). The desirability of network coding in funnel networks may be justified by the other benefits that coding offers. However, we see that in funnel networks, the conventional random approach to linear coding fails with high probability. Hence, we provide a new random linear network coding solution for these non-multicast problems. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
46. A Low Complexity Two-Stage LLR Detector for Downlink OFDM-IM NOMA.
- Author
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Sabud, Subham and Kumar, Preetam
- Abstract
OFDM-IM based Non-Orthogonal Multiple Access is a recently developed scheme, where flexibility is provided by both NOMA and OFDM-IM with an adjustable power allocation coefficient and an adjustable subcarrier activation ratio, respectively. However, the computational complexity of the Maximum Likelihood (ML) detector, used in the OFDM-IM NOMA scheme is very high. In this letter, a low complexity “two-stage Log-Likelihood Ratio (LLR)” detector is proposed for the OFDM-IM NOMA scheme. Computer simulation results and complexity analysis verify that the proposed detector performs almost the same as the ML-based detector in all the various conditions, with much reduced computational complexity. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
47. NOMA Joint Channel Estimation and Signal Detection Using Rotational Invariant Codes and GMM-Based Clustering.
- Author
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Salari, Ayoob, Shirvanimoghaddam, Mahyar, Shahab, Muhammad Basit, Li, Yonghui, and Johnson, Sarah
- Abstract
This letter studies the joint channel estimation and signal detection for the uplink power-domain non-orthogonal multiple access. The proposed technique performs both detection and estimation without the need of pilot symbols by using a clustering technique. We apply rotational-invariant coding to assist signal detection at the receiver without sending pilot symbols. We utilize Gaussian mixture model (GMM) to automatically cluster the received signals without supervision and optimize decision boundaries to improve the bit error rate (BER) performance. Simulation results show that the proposed scheme without using any pilot symbol achieves almost the same BER performance as that for the conventional maximum likelihood receiver with full channel state information. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
48. Performance Analysis of Cooperative Wireless Networks With Unreliable Backhaul Links.
- Author
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Khan, Talha Ahmed, Orlik, Philip, Kim, Kyeong Jin, and Heath, Robert W.
- Abstract
A cooperative wireless network, where a cluster of $K$ single-antenna transmitters jointly serve a single-antenna receiver, is considered. Each transmitter is connected to the control unit (CU) via independent but unreliable backhaul links. The CU sends a common message to each transmitter over backhaul links, which upon successful reception, jointly transmit this message to the intended receiver. To facilitate analysis, a general expression is derived for the complementary cumulative distribution function of a sum of $K$ independent random variables, where each random variable is a product of an exponential and a Bernoulli random variable. This result is applied to find a simple closed-form expression that characterizes the system outage performance as a function of network parameters and node geometry. The analytical model is validated using numerical simulations. As an application, the derived expression is also used for investigating the impact of backhaul assignment on the system performance. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
49. Secure GDoF of $K$-User Gaussian Interference Channels: When Secrecy Incurs No Penalty.
- Author
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Geng, Chunhua and Jafar, Syed A.
- Abstract
Recently, Geng et al. have shown that from the perspective of generalized degrees of freedom (GDoF), power control and treating interference as noise (TIN) is optimal for a broad class of Gaussian interference channels. In this work, we show that for TIN-optimal interference channels identified by Geng et al., secrecy constraints on unintended messages incur no GDoF penalty, which leads us to a secure capacity region characterization within a constant gap. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
50. Efficient Receiver Architecture for LDPC Coded BICM-ID System.
- Author
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Cheng, Tao, Peng, Kewu, Liu, Zaishuang, and Yang, Zhixing
- Abstract
The low-density parity-check (LDPC) coded bit-interleaved coded modulation with iterative demapping (BICM-ID) has excellent bit error rate (BER) performance, but with extremely high receiver complexity. This letter proposes a three-stage full-parallel receiver architecture in which each component decoder is separately but simultaneously iteratively decoded. This architecture can make full use of the computing resources and improve the system performance without sacrificing the throughput. Three-dimensional (3-D) extrinsic information transfer (EXIT) analysis and BER simulations are carried out to demonstrate the superiority of the proposed new receiver architecture. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
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