Current spectral simulations of Einstein’s equations require writing the equations in first-order form, potentially introducing instabilities and inefficiencies. We present a new penalty method for pseudospectral evolutions of second order in space wave equations. The penalties are constructed as functions of Legendre polynomials and are added to the equations of motion everywhere, not only on ...

The spectral efficiency of a hybrid cellular direct-sequence/frequency hopping code-division multiple-access (DS/FH-CDMA) system operating in a Rayleigh-fading environment is examined. In this work, spectral efficiency is evaluated in terms of the theoretically achievable channel capacity (in the Shannon sense) per user, on the condition that this is estimated in an average sense. The analysis ...

Adaptive modulation exploits the time-variant channel capacity uctuation of fading channels using a range of di erent modem modes according to Equation 1 and Table1. This is achieved at the cost of some latency penalty, which is quanti ed in this treatise and mitigated by frequency hopping.

there are many different ways to subdivide the spectrum of a bounded linear operator; some of them aremotivated by applications to physics (in particular, quantum mechanics). in this study, the relationship betweenthe subdivisions of spectrum which are not required to be disjoint and goldberg's classification are given.moreover, these subdivisions for some summability methods are studied.

The effect of wall and indoor scatterers on the indoor multiple input multiple output (MIMO) communication system is investigated by using the hybrid technique of finite difference time domain (FDTD) method and method of moments (MoM). MIMO channel capacity with the wall reflection is investigated with consideration of the eigenvalue of channel covariance matrix, the received power and the effe...

Parallel rendezvous multi-channel MAC mechanisms are regarded as an efficient method for media access control in cognitive radio networks since they do not need a control channel and use only one transceiver. However, existing parallel rendezvous MAC mechanisms assume that all channels have the same maximum capacity and channel availability for secondary users. In this paper, we propose a dynam...

Using the enhanced data rates for GSM evolution (EDGE) system with cyclic frequency hopping as an example, we apply a Kalman-filter power control method based on interference tracking to packet voice service in wireless networks. Our results show that the power-control method significantly improves the spectral efficiency by enabling the 1/3 frequency reuse while maintaining a stringent require...

| In this paper we study the system capacity of cellular systems with time-division multiple access and slow time-frequency hopping (F-TDMA). System capacity is deened as the number of users/cell bit/s/Hz, for a given maximum outage probability. Outage is deened as the event that the mutual information of the interference channel falls below the actual code rate. We develop a general framework ...

The optimization between the average received power and the theoretically achievable average channel capacity per user (in the Shannon sense) of a hybrid direct-sequence/fast frequency hopping codedivision multiple-access (DS/FFH-CDMA) cellular system, when operating in a Rayleigh fading environment, is presented. The analysis leads to a novel-closed form expression for the optimal average rece...

The channel capacity of the indoor multiple input multiple output (MIMO) system is investigated with consideration of the effects of the wall by using a hybrid method of the finite difference time domain (FDTD) method and the method of moments (MoM). Firstly, the effects of wall material on indoor MIMO channel capacity are investigated according to the physical parameters of the wall, i.e. the ...