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This paper addresses the robust transceiver optimization in multiple-input and multiple-output cognitive radio network, where primary users (PUs) and secondary users (SUs) coexist in the same spectrum band. In the design of cognitive system, the performance degradation perceived by PU should be strictly restricted even with imperfect channel state information (CSI) at cognitive transmitter and receivers...
The transmission capacity of an ad-hoc network is the maximum density of active transmitters in a unit area, given an outage constraint at each receiver for a fixed rate of transmission. Most prior work on finding the transmission capacity of ad-hoc networks has focused only on one-way communication where a source communicates with destination and no data is sent from destination to the source. In...
In this paper, we first investigate the Degrees Of Freedom (DOF) for the M-user Interference Channel (IC) in static environments with the help of a MIMO relay. The relay stores the received signal during the first time-slot and sends a linearly-transformed version over the next time-slot. Using this scheme, it is shown that Interference Alignment can be done with much less complexity. Having very...
We consider a dense n-user Gaussian interference network formed by paired transmitters and receivers placed independently at random in Euclidean space. Under natural conditions on the node position distributions and signal attenuation, we prove convergence in probability of the average per-user capacity CΣ/n to ½ E log(1 + 2SNR). The achievability result follows directly from results based on an interference...
A new underwater acoustic (UWA) communication system is proposed based on fractional Fourier transform (FRFT) for complex condition of underwater environment. Because of using chirp-basis function in FRFT, this communication mode uses linear frequency modulation (LFM) as carrier signal of transmitted information, which has good anti-jamming capability. The code elements were divided into groups in...
In this paper, we consider the interference caused by a secondary system to the primary system in a cognitive radio network. We consider a secondary system deployed in a field of primary receivers. Primary receivers are assumed to be distributed according to a Poisson point process with a density parameter λp. We assume that the secondary system consists of source, relay, and destination terminals,...
In this paper, we introduced an adaptive cumulative layered multicast scheme, ACLM, to address multicast receivers' heterogeneity in available bandwidth. ACLM uses an optimal layer rate allocation algorithm which can maximally satisfy each receiver's available bandwidth. Through a novel feedback aggregate algorithm, ACLM dynamically determines the number of layers and the rate of each layer. Simulation...
In orthogonal frequency division multiple access (OFDMA) uplink system, orthogonal multiple subcarriers are assigned to different users for parallel high data rate communications. However, carrier frequency offset (CFO), which is mainly due to oscillator mismatches and/or Doppler shift, will destroy the orthogonality among subcarriers and introduce intercarrier interference (ICI) as well as multiple-access...
Dynamic Spectrum Leasing (DSL) is a new paradigm for efficient spectrum sharing in cognitive radio networks that was recently proposed in. Unlike in a hierarchical dynamic spectrum access (DSA) network, DSL allows active participation of both the primary and the secondary users in the spectrum sharing process. In this paper we further generalize the DSL game introduced in by allowing for linear multiuser...
Impulse-radio ultra-wideband (IR-UWB) radios are slated to be the next generation of transceivers that can support power-constrained applications such as wireless sensor and body area networks. However, despite inherent advantages of UWB transmission due its large signal bandwidth, adoption of IR-UWB radios is hampered by relatively complex receiver structures. In this overview paper, we will first...
Maximizing the battery life time of mobile devices and sensor nodes increasingly becomes a challenge, and receiver power consumption tends to become more problematic than delivering adequate transmit power. We address the challenge of achieving the highest possible throughput per Watt of receiver circuit power. Our results show that optimum and adaptive tuning of the front-end parameters of the receiver...
We consider the design of ultra-wideband (UWB) systems that provide high capacity communication for short-range wireless applications. The design configuration is a multiuser pre-rake UWB broadcast communication system in which the base station is equipped with multiple antennas to achieve high data rates while each user is equipped with a simple and cost-efficient single antenna receiver. We assume...
Relays can be used between the source and the destination to improve network coverage or reliability. In the relay based distributed space-time block-coded (DSTBC) single-carrier (SC) transmission scheme, asynchronism in time and frequency causes degradation in system performance because of the interblock interference, non-coherent combining and multiuser interference. The simultaneous presence of...
A two-user uplink interference channel with hybrid automatic retransmission request (HARQ) and base station cooperation is analyzed. Two forms of base station cooperation are studied: wireless and wireline cooperation. In wireless cooperation, the first base station that decodes its desired user's message acts as a relay for the co-channel user via space-time coding during the remaining HARQ rounds...
In this paper, the rate achievable in Multiple-Input-Multiple-Output (MIMO) systems with iterative receivers based on linear front-end (FE) processing is investigated. First, the communication with Gaussian input signal is assumed and the Extrinsic Information Transfer (EXIT) chart is applied to evaluate the achievable sum rate. Then, the method for deriving the EXIT chart for a more practical case...
In this paper, we propose a practical nullspace-based secondary joint transceiver scheme for the coexistence of a secondary system and a primary system in cognitive radio MIMO (CR-MIMO) networks using second-order statistics. First, we propose a secondary transmission frame structure, and briefly describe the periodical nullspace sensing procedure for both the secondary transmitter (ST) and secondary...
This paper analyzes the interference in Direct Sequence Spreading Spectrum (DSSS) systems with Selective RAKE (SRAKE) receivers where channel delay is comparable with spreading sequence length. We build an accurate output model of SRAKE receiver and derive the output Signal to Interference-Noise Ratio (SINR) and Bit Error Rate (BER) of SRAKE receiver, taking multipath effect into consideration. Based...
We propose a b-bit non-coherent receiver based on a Digital Code Matched Filter (DCMF) for a low data rate Time- Hopping Pulse Position Modulation Ultra Wide Band (TH-PPMUWB) system. The DCMF follows after a high-speed but lowresolution (b-bit, 1 ≤ b ≤ 4) Analog-to-Digital Convertor (ADC) and is employed before the non-coherent detection. It is matched to the user-specific sequence and restricts the...
In this paper, a closed-loop wireless communication system employing Quasi-Orthogonal Space-Time Block Codes (QOSTBCs) is presented, where the total available power can be suitably allocated to the four transmit antennas, considering a very low-complexity decoding scheme at the receiver side. After deriving a particular optimization problem concerning the optimal choice of the power weights, we prove...
A novel method is proposed in this paper to cancel the image-band interference for multi-mode/band receivers with baseband AGC. The Hilbert transformer, which plays an important part in heterodyne multi-mode receivers described here, has the imperfection which results in image-band interference in baseband, causing severe deterioration of transmission performance. The method proposed here cancels...
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