In this paper, we extend the well-known model for the Gaussian Cellular Multiple Access Channel originally presented by Wyner. The first extension to the model incorporates the distance-dependent path loss (maintaining a close relevance to path loss values in real world cellular systems) experienced by the users distributed in a planar cellular array. The density of base stations and hence the cell sizes are variable. In the context of a Hyper-receiver joint decoder, an expression for the information theoretic capacity is obtained assuming a large number of users in each cell. The model is further extended to incorporate the log-normal shadow fading variations, ensuring that the shadowing models are fairly comparable to the free space model. Using these fair models the effect of the shadow fading standard deviation on the information theoretic capacity of the cellular system is quantified. It is observed that a higher standard deviation results in lower capacity if the mean path loss is appropriately adjusted in order to model the mean loss due to the physical obstacles causing the shadow fading. The results validate that larger cell sizes and a higher standard deviation of shadowing (with appropriately adjusted mean path loss) results in lower spectral efficiency.

Higher spectral efficiency can be achieved by exploiting the space dimension inherent to any wireless communication system using multiple receiver and multiple transmitter antennas (MIMO). There are several results that provide closed form solutions for acellular system with a single antenna at each base station and each user terminal. Results are also available for the single cell case with MIMO. A cellular system with multiple antennas at the transmitter and the receiver nodes has not been investigated to obtain a closed form solution for the capacity limit. The main information theoretic theorems are not directly applicable to this system because of the form of the channel matrix of such a system. In this paper we extend the well known Wyner's model to a MIMO cellular system. It is observed that the achievable rate is bound by an upper limit and lower limit corresponding to two extreme fading conditions: channel with Rayleigh fading and with no fading. The analytical results are verified using Monte Carlo simulations. The analysis provides the insight that for a cellular system, increasing the number of transmitting antennas is not beneficial to increase the achievable rate, and this is reflected in the results obtained.

In this work we investigate the information theoretic capacity of the uplink of a cellular system. Assuming centralised processing for all base stations, we consider a power-law path loss model along with variable cell size (variable density of Base Stations) and we formulate an average path-loss approximation. Considering a realistic Rician flat fading environment, the analytical result for the per-cell capacity is derived for a large number of users distributed over each cell. We extend this general approach to model the uplink of sectorized cellular system. To this end, we assume that the user terminals are served by perfectly directional receiver antennas, dividing the cell coverage area into perfectly non-interfering sectors. We show how the capacity is increased (due to degrees of freedom gain) in comparison to the single receiving antenna system and we investigate the asymptotic behaviour when the number of sectors grows large. We further extend the analysis to find the capacity when the multiple antennas used for each Base Station are omnidirectional and uncorrelated (power gain on top of degrees of freedom gain). We validate the numerical solutions with Monte Carlo simulations for random fading realizations and we interpret the results for the real-world systems.

In the information-theoretic literature, multicell joint processing has been shown to produce high spectral efficiencies. However, the majority of existing results employ simplified models and normalized variables and in addition they consider only the sum-rate capacity, neglecting the individual user rates. In this paper, we investigate a realistic cellular model which incorporates flat fading, path loss and distributed users. Furthermore, the presented results are produced by varying the cell density of the cellular system, while practical values are used for system parameters, such as users per cell, transmitted power, path loss exponent. What is more, we study the effect of sum-rate maximization on the fairness of user rate distribution by comparing channel-dependent and random user orderings within the joint encoding/decoding process.

In this paper, we extend the well-known model for Gaussian Cellular Multiple Access Channel originally presented by Wyner and later extended by Somekh et al. with fading. The extension to the model, incorporates the distance dependent path loss (maintaining a close relevance to path loss values in real world cellular systems) experienced by the users distributed in a planar cellular array. The density of base stations and hence the cell sizes are variable. In the context of Hyper-receiver joint decoder, a closed form expression for the information theoretic capacity is obtained assuming large number of users in each cell. The effect of the path loss factor, on the information theoretic capacity of the cellular system, is quantified and it is observed that higher path loss factor results in lower capacity. The results validate that larger cell sizes result in lower spectral efficiency. The closed form formula derived by the mathematical analysis is also validated by Monte Carlo simulations.

In this paper we derive the information theoretic capacity of the uplink of a cellular system with variable inter site distance and a generalised fading environment. The capacity is shown to be a direct function of the ratio of total received signal power (from within and outside of a cell) to the AWGN noise power, at any BS. This ratio is defined as the rise over thermal (RoT). It is shown that the variation in system parameters like the path loss exponent, number of users, transmit power constraint and the inter site distance, changes the region of operation on a capacity-versus-RoT curve. Results are interpreted for practical channel models and it is shown that RoT provides a useful framework to compare various practical systems.

Applying relaying concept to a universal mobile telecommunications system (UMTS) mobile network is not a new idea, and many systems employing relaying capabilities have been suggested. The power control (PC), which is an important aspect of UMTS, can be applied in such a mobile system, either in a centralised or a distributed fashion. An increase in the system capacity is expected, when utilised in all system links, single-hop (SH) and multi-hop. This is because the PC allocates, to the transmitters, the minimum powers which satisfy the link quality criteria. In this paper we formulate the transmit powers of a relaying system. We then compare, in an example, the power convergence of an iterative PC to the solution provided by the suggested equations. The assumptions, which facilitate rendering the formulations to a linear set of equations, are analysed.

The time-domain (TD) solutions for the reflection and transmission through a dielectric slab case are presented. In contrast to other existing solutions, the proposed ones can incorporate correctly the multiple internal reflections inside the slab in simple and easy-to-use closed forms. The comparison of the proposed solutions against the numerical inverse Fourier transform of the received waveforms as these were calculated in the frequency domain reveals an extremely good agreement and validates the correctness of our TD forms.

In this paper we propose an empirical radio propagation model for the relaying system with low height terminals. The model differentiates line-of-sight (LOS) and non-line-of-sight (NLOS) propagation paths for increased accuracy by employing an easy-to-use expression. It takes into account the effect of transmitter height, receiver height, receiver location and environmental parameters and it is also complemented by shadow fading statistics, namely the distribution and autocorrelation function estimation. Finally, cell coverage for mobile-to-mobile systems is also discussed.

The relaying concept utilises the non-linear character of the radio propagation at the expense of engaging additional resources. This paper investigates the benefits from employing relaying in multiple frequencies, as opposed to a single band. Rearrangement of the communication links among the resources can convey the interference from the user terminals to the base station receiver at the operator's choice. Applying relaying on alternate sites and using concurrent uplink connection throughout the system is shown to perform substantially better than other frequency relay options.