The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A new censoring cooperative spectrum sensing scheme in cognitive radio (CR) network is proposed in this paper, which is based on stochastic resonance (SR) technique and optimal censoring interval. The selection strategy for the optimal censoring interval is derived. The observations of the cooperative secondary users (SUs) whose statistics fall into the censoring interval are processed by SR system...
A cooperative spectrum sensing technique in cognitive radio (CR) networks is proposed in this paper, which is based on the data fusion of different stochastic resonance (SR) energy detectors. Due to the noisy uncertainty in the unpredictable wireless communication channel, the detection performance of the traditional energy detector cannot be guaranteed. By introducing the SR system with different...
The advantage of using channel feedback information to determine the optimal pilot placement is examined for amplify-and-forward OFDM relay links. This work extends upon the previously proposed feedback-aided pilot placement scheme to systems that employ subcarrier pairing at the relay. With channel feedback, the pilot subcarriers can be properly chosen to reduce the channel estimation error and increase...
In this paper, we propose a dynamic power allocation scheme for a single-relay network based on orthogonal frequency division multiplexing (OFDM) modulation with limited feedback.We consider an Amplify-and-Forward (AF) cooperative diversity model, where one source node communicates with one destination node assisted by one half duplex relay. The power allocation scheme employs a codebook of quantized...
Transaction management for mobile and ubiquitous computing aims at providing mobile users with reliable services in a transparent way anytime anywhere. To make such a vision a reality, transaction processing for the mobile and ubiquitous computing needs to adapt to the runtime environments dynamically. However, most existing mobile transaction models do not consider the context-based transaction management...
This paper addresses bounds on the transmission capacities of two coexisting wireless networks (a primary and a secondary network), where each with multiple antennas shares the same spectrum and operates in the same geographic region. In the two coexisting network, the secondary (SR) network limits its interference to the primary (PR) network by carefully controlling its active transmitter density...
This paper proposes multiple-input multiple-output (MIMO) transmission in fixed gain amplify-and-forward relaying to allow for high data rate coverage in wireless distributed networks. We consider a hierarchical network architecture in which the relay is a multiple antenna static node assisting single antenna mobile nodes. We derive new exact closed-form expressions for the outage probability and...
In this paper we propose a general model to estimate the maximum allowed transmit power of a secondary node based on the measured signal from the primary transmitter that is willing to share its downlink spectrum. The transmit power should satisfy primary constraints related to the minimum required Signal to Interference and Noise Ratio (SINR) of its users. The model can be used by secondary nodes...
Initial works on cooperative vehicular communications build upon the assumption of frequency-flat and quasi-static fading channels. This can be justified only for narrowband systems in very slow traffic flows such as in rush-hours. In this paper, we consider doubly-selective (i.e., time- and frequency-selective) vehicular channels and investigate multipath-Doppler diversity for a cooperative vehicular...
In this paper, we propose power budget allocation algorithms for bidding of auctions in cooperation-based spectrum leasing. The cooperation-based spectrum leasing allows secondary users to dynamically access licensed bands while providing the benefit of cooperative diversity to primary users as a reward. For efficient allocation of the licensed bands to the secondary users, a second-price based multiple...
Regular LDPC codes tend to have better error-floor behavior than irregular LDPC codes. However, for moderate block lengths and high rates, the error floor remains a concern even for regular LDPC codes. This is especially the case for applications such as memory media that require very low frame error rates (FERs). This paper focuses on a class of regular LDPC codes: separable, circulant-based (SCB)...
We propose a distributed spectrum access algorithm for cognitive radio relay networks with multiple primary users (PU) and multiple secondary users (SU). The key idea behind the proposed algorithm is that the PUs negotiate with the SUs on the amount of time the SUs are either (i) allowed spectrum access, or (ii) cooperatively relaying the PU's data, such that both the PUs' and the SUs' minimum sum-rate...
A complete evaluation of the benefits of cooperative diversity schemes should not only include the outage and error rate performance but also the second-order statistics of the achievable information-theoretic capacity. In a non-ergodic fading channel, the system is said to be in outage when the destination cannot decode the fixed-rate transmitted signal with negligible error probability. Because...
Rapidly repeating the original packet multiple times has been found to improve the probability of successful reception of a packet in error-prone vehicular communication environment. However, since each repetition increases channel load, performance of repetition-based loss recovery starts to deteriorate with increasing number of vehicles on the road. This paper explores the benefit of Network Coding...
In this paper, we investigate the range of the achievable diversity order of opportunistic relay selection with M amplify-and-forward (AF) relays and N users. We show that the opportunistic selection of the relay-user pair with the best end-to-end signal-to-noise ratio (SNR) achieves a diversity order between M+N and MN+N. Our analysis reveals that the achievable diversity order depends on the SNR...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.