Abstract
The capacity of 4G cellular wireless networks like Long Term Evolution Advanced can be increased by larger bandwidth for multicarrier operation, higher number of antennas for more spatial multiplexing, tighter reuse of radio cells using the same frequency spectrum and optimisation of the network configuration in general. The potentially higher capacity will be achieved only if the whole wireless network can be more or less perfectly adapted to the existing real environment at any time. This real environment which includes for example the radio channel, the user traffic, the equipment performance and the network configuration can change, however, within a time scale of a wide range from below 1 ms up to more than 100 s. Appropriate linear or nonlinear adaptive techniques which are able to track these changes are described for wideband linear power amplifier, multiple input multiple output antenna systems, heterogeneous networks and self-organising networks including the corresponding realisation and performance aspects.
Highlights
The theoretical upper limit for the capacity C [bit/s] of radio cells using multiple antenna systems can be estimated by a modified version of Shannon’s channel capacity theorem [1, 2]: C = A · B · log2 + I S + N (1)A larger bandwidth B, a higher number A of spatial streams by using more antennas and higher order modulation by using a better signal power S to the interference plus noise power I + N ratio (SINR) can increase the capacity C of a radio cell
This paper provides a rough estimate on the complexity of the TX model H, which can be written as a timediscrete Volterra series, using the sampling rate fS = 1/TS of the Digital-toanalogue conversion (DAC) as time basis t = nTS: P
6 Conclusions Different adaptive techniques have been presented for different layers of a cellular wireless network based on the Long Term Evolution (LTE)-Advanced standard
Summary
The theoretical upper limit for the capacity C [bit/s] of radio cells using multiple antenna systems can be estimated by a modified version of Shannon’s channel capacity theorem [1, 2]:. Co-existence with other radio technologies is typically achieved by spectral separation, i.e. the operating channel bandwidth is disjunct from the other services. Digital channel filters can be implemented with sufficient stopband attenuation for isolation from other radio technologies. Another condition for co-existence are sufficiently low distortions in the analogue RF part of TX and RX— similar to requirements 2 and 4. Reduce distortions of the TX and the RX Protect the RX from the own TX Calibration of TX and RX paths for multi-antenna systems Within these areas, most computing power is used to reduce the distortions in the TX mainly in the WLPA, when wideband applications like carrier aggregation (CA) or multistandard radio (MSR) need to be supported
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