Multitone modulations are today frequently used modulation techniques that enable optimum utilization of the frequency band provided on non-ideal transmission carrier channel (Bingham, 2000). These modulations are used with especially in data transmission systems in access networks of telephone exchanges in ADSL (asymmetric Digital Subscriber Lines) and VDSL (Very high-speed Digital Subscriber ...

Priority-based model of subchannel allocation in WiMAX downlink is presented, which is based on solution of the optimization problem associated with maximizing the lower weighted bound of allocated bandwidth for each subscriber station according to its quality of service requirements for access rate and priority. Numerical research of model showed that increasing of the bandwidth requirements o...

| Multicarrier modulation possesses several properties which make it an attractive approach for high speed copper wire communications networks. Among these properties are the ability to eeciently access and distribute multiplexed data streams, and a reduced susceptibility to impulsive, as well as to narrowband channel disturbances. In digital implementations of multicarrier modulation, subcarri...

Abstract— The fading wire-tap channel is investigated, where the source-to-destination channel and the source-to-wire-tapper channel are corrupted by multiplicative fading gain coefficients in addition to additive Gaussian noise terms. The channel state information is assumed to be known at both the transmitter and the receiver. The parallel wire-tap channel with independent subchannels is firs...

Device-to-Device (D2D) communication, which enables direct communication between nearby mobile devices, is an attractive add-on component to improve spectrum efficiency and user experience by reusing licensed cellular spectrum. Nowadays, LTE-unlicensed (LTE-U) emerges to extend the cellular network to the unlicensed spectrum to alleviate the spectrum scarcity issue. In this paper, we propose to...

Multi-input multi-output (MIMO) channels have been shown in the literature to present a significant capacity increase over single-input single-output ones in some situations. To achieve this theoretical capacity, the constituent parallel subchannels arising from the MIMO channel have to be properly used. Many practical schemes are being currently developed to achieve this goal. In this paper, w...

In a discrete multitone receiver, a time-domain equalizer (TEQ) reduces intersymbol interference (ISI) by shortening the effective duration of the channel impulse response. Current TEQ design methods such as minimum mean-squared error (MMSE), maximum shortening SNR (MSSNR), and maximum geometric SNR (MGSNR) do not directly maximize bit rate. In this paper, we develop two TEQ design methods to m...

Frequency-selective channels can be converted into a set of flat fading subchannels by employing Orthogonal Frequency Division Multiplexing (OFDM). Conventional differential encoding on each subchannel, however, suffers from loss of multipath diversity, and yields non-constant modulus transmissions, which causes undesirable non-linear effects. To mitigate these effects, we design a block differ...

We propose using punctured convolutional code for a Discrete Multitone (DMT) Asymmetric Digital Subscriber Line (ADSL) system to improve the data rate performance of ADSL. The theoretical performance of the systems with single coding rate for all subchannels, and with adaptive coding rate for each subchannel are presented respectively. It is found that the data rate performance of the proposed ...