[Show abstract][Hide abstract] ABSTRACT: In this paper, a modified sequential probability ratio test (SPRT) scheme, namely sequential energy detection (SED), is proposed for cooperative spectrum sensing to reduce the average number of required samples. In the scheme, the data samples are first grouped into data blocks and the sequential probability ratio test (SPRT) use the energies of the data blocks as the statistics variables. The resulting detection rule exhibits simplicity in implementation and in analysis and avoid the deterministic knowledge of primary signals. The detection performance in terms of average sample number (ASN) is evaluated theoretically. Numerical results are provided to verify the theoretical analysis.
[Show abstract][Hide abstract] ABSTRACT: Recently, an energy efficient noncoherent receiver scheme, called codeword matching and signal aggregation (CMSA), has been proposed for ultra-wideband (UWB) communications. However, its optimality and analytical error performance have not been studied. This letter shows the CMSA receiver is the optimal receiver in the sense of generalized likelihood ratio test (GLRT) and presents closed-form upper bound expression for bit error probability (BEP).
No preview · Article · Jun 2010 · IEEE Communications Letters
[Show abstract][Hide abstract] ABSTRACT: Noncoherent receivers are attractive for ultra wideband (UWB) impulse radio systems due to the implementation simplicity. Recently, a block differential transmission scheme was proposed to improve the maximum achievable data rate of noncoherent UWB systems. In this paper, based on the generalized likelihood ratio test (GLRT) optimization criterion, we derive a novel multiple symbol differential detection (MSDD) receiver under block differential transmission framework. Compared with the conventional symbol-by-symbol differential detection (DD) receiver, the proposed MSDD receiver has better performance at the cost of increased computational complexity. We thus propose a reduced-complexity implementation of the MSDD by using a two-step search strategy.
[Show abstract][Hide abstract] ABSTRACT: In cognitive radio networks, multiple cognitive radio nodes perform spectrum sensing cooperatively in order to detect the primary user more accurately. Previous works on cooperative spectrum sensing have shown that the detection performance can be improved through increasing either the observation interval or the number of the sensing nodes. However, increasing the observation interval will result in the reduction of transmit efficiency and the agility of cognitive users, and at the same time increasing the number of sensing nodes may lead to the overhead increase of control channel and computational complexity. In this paper, we formulate the tradeoff relation between the observation interval and the number of the sensing nodes under the constraint of required detection performance. The numerical results show the proposed relation.
[Show abstract][Hide abstract] ABSTRACT: Proposed is a novel ultra-wideband energy detection receiver based on multiple symbol differential detection (MSDD), which bypasses explicit channel estimation by using the autocorrelation principle. Simulation results show that the proposed MSDD-based receiver performs considerably better than the conventional energy detection receiver in the medium to large signal-to-noise ratio region.
No preview · Article · Oct 2009 · Electronics Letters
[Show abstract][Hide abstract] ABSTRACT: Non-coherent energy detection receiver is an attractive solution for impulse radio ultra-wideband (IR-UWB) systems due to the low implementation complexity. In this paper, we propose a novel weighted non-coherent energy detection receiver for on-off keying (OOK) UWB systems in multi-path environment. The performance of this receiver is improved by weighting the subinterval integrator output with a function related to the channel energy delay profile. Signal subintervals with larger energy contributions are given larger weights, thus improving the receive signal-to-noise (SNR). The error probability of proposed receiver is analyzed, and its superiority over the conventional one is examined by numerical results using IEEE 802.15.4a channel model.
[Show abstract][Hide abstract] ABSTRACT: In cognitive radio networks, the cognitive radio users can be collaborated to perform spectrum sensing so as to detect the primary user more accurately. However, when the sensing nodes suffer from fading, shadowing, and time-varying nature of wireless channels, it needs to set a long observation time for all of the nodes to make decisions and forward the results to fusion center, which induce the severe degradation of the sensing performance. In this paper, we propose an asynchronous cooperative spectrum sensing method, in which the cognitive radio user with high SNR finishes the detection earlier than the one with low SNR, and the fusion center makes the final decision depending on the earliest local decision. The proposed method can exploit the userpsilas SNR diversity so that the sensing performance can be enhanced. Simulation results show that the detection time is reduced significantly at the expense of a little sensing performance degradation compared to the conventional cooperative spectrum sensing.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we propose a rapid time of arrival (TOA) estimation method, which is suitable for low complexity and low cost UWB systems. We develop an iterative algorithm that applies multi-scale sliding correlation window to reduce the system complexity and speed up the estimation process. In order to improve the accuracy of TOA estimation in the presence of multi-user interference (MUI), the perfectly balanced ternary sequence (PBTS) is employed as spreading code to suppress MUI. Through simulations, we show the MAE (mean absolute error) performance for proposed TOA estimation method in IEEE 802.15.4a channel model.
[Show abstract][Hide abstract] ABSTRACT: This paper investigates the critical connectivity phenomena in the large-scale wireless sensor network with continuum percolation theory. We analyze the critical number of nodes and critical transmit radius that above which the network is fully connected. The impact of node reliability on network connectivity is also studied and discussed. Our results are of practical value for the design and simulation of wireless sensor networks.