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The exact outage probability (OP) of cognitive dual-hop relay networks equipped with a single amplify-and-forward (AF) relay and a selection combining receiver at the destination is derived under spectrum sharing constraint on a primary user. The tractable closed-form OP readily enables evaluation of system performance, which indicates the significance of using a relay in cognitive radio networks with a spectrum sharing approach. The proposed analysis is validated by numerical examples. [ABSTRACT FROM AUTHOR]

Proposed is a novel ergodic capacity formula for decode-and-forward (DF) relaying over a very general fast fading channel model, i.e. the channel gains of the links follow independent but non-necessarily identically distributed Nakagami-m distributions. The proposed formula is validated by Monte Carlo simulations and can be computed efficiently. Since the considered channel model is very general, the proposed formula is appropriate for evaluating the performance of DF relaying in a wide variety of realistic wireless channel environments. [ABSTRACT FROM AUTHOR]

The overall outage probability of a two-way amplify-and-forward relaying system with opportunistic relay selection is investigated over Nakagami-m fading channels, and a tight closed-form approximation is derived. Further, closed-form expressions for the overall diversity and coding gains are obtained. Simulation results are presented to verify the analysis. Using these expressions, one can evaluate the outage performance, diversity and coding gains of a two-way relaying system easily and fast. [ABSTRACT FROM AUTHOR]

A decode-and-forward two-hop relay network exploiting spatial diversity is considered. By considering transmission overheads in detail to exploit spatial diversity, an explicit expression is derived for the average transmission capacity of the relay network, which is a function of the transmission time and coding rate by the source. Some numerical examples based on analysis are provided to demonstrate performance behaviour. [ABSTRACT FROM AUTHOR]

The outage probability (OP) of multiple-input multiple-output (MIMO) amplify-and-forward (AF) relay networks using orthogonal space-time block code is investigated. In particular, a closed-form tight lower bound expression for the OP over independently but not necessarily identically distributed Nakagami-m fading channels is derived. Moreover, an asymptotic approximation for OP which reveals the coding and diversity gains is presented. The analytical expressions are validated by Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

The outage performance of a multiple-input multiple-output (MIMO) relay system over slow frequency-nonselective fading channels, where maximal ratio transmission is adopted at both the source and relay transmitters whereas maximal ratio combining is used at relay and destination receivers, is investigated. A closed-form expression for the outage probability is presented. Numerical results are presented to verify the analysis. [ABSTRACT FROM AUTHOR]

A modified meander line monopole antenna is presented for broadband operation. The impedance and radiation characteristics of the antenna are investigated. The proposed antenna achieved a bandwidth of approximately 845 MHz with S11<-10 dB, which covered the GPS, DCS, PCS, UMTS and WiBro bands. The electrical characteristics of the proposed antenna appear to be attractive for mobile terminals and repeater applications. [ABSTRACT FROM AUTHOR]

2.5 Tbit/s transmission of 12.5 GHz-spaced 256 ultra-dense wavelength-division-multiplexing (WDM) channels over a standard singlemode fibre of 2000 km with a repeater spacing of 100 km is presented. A non-return-to-zero modulation format and C-band erbium-doped fibre amplifiers are exclusively used. The results demonstrate the upgradability of conventional WDM transmission networks towards UD-WDM transmission networks. [ABSTRACT FROM AUTHOR]

Formation of virtual antenna arrays among neighbouring nodes and their co-operative transmission have attracted increasing interest. The exact outage probability of co-operative communication with multiple amplify-and-forward relays is given. The analysis covers general relay topologies and is verified by Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

A 40 W gallium-nitride microwave Doherty power amplifier for WCDMA repeater applications is presented. The main amplifier and peaking amplifier are implemented using two 20 W PEP GaN HEMTs. Performance is evaluated for broadband gain, power efficiency and adjacent-channel-power-ratio (ACPR). Experimental results of the GaN Doherty amplifier yielded a power gain of over 11 dB from 1.8 to 2.5 GHz, 68% power added efficiency at 40 W peak power. Good linearity performance of -48 dBc ACPR is obtained at a peak-to-average ratio of 9.8 dB. [ABSTRACT FROM AUTHOR]