capacity and performance evaluation of LTE networks

OData support
Dr. Fazekas Péter
Department of Networked Systems and Services

The next generation wireless network system of the 3GPP standards-developing organization is the LTE (Long Term Evolution). At the phase of designing LTE, the primary goal was to multiply the throughput of the system. Since current technologies and the networks do not allow that, the main keystones of the new system are the new architecture and a more effective physical radio access technology, the OFDMA (Orthogonal Frequency Division Multiple Access). The requirement of the radio transmission is about 100 Mbit/s peak data-rate, when operating in 20 MHz spectrum allocation.

However the achieveable data-rate is affected by some disturbing factors. These are important in the planning of system performance. In my analysis, the path loss is considered by estimating urban propagation with the Hata-model. The transmission is also influenced by inter-cell interference, resulted from the transmission of other base stations; thermal noise is also taken into account. Given the signal-to-noise ratio, the useful data-rate can be calculated with taking forward error correction and adaptive modulation. The achieved data-rate in the physical layer does not tell us exact informations about the performance, the overhead caused by several control channels (which are to manage the network) and reference signals have to be subtracted. After that calculation we get a more suggestive data-rate.

The energy consumption of the network is also of utmost importance. The new network achieves higher performance, but the amount of the energy consumed might also grow. Determining the number, range and transmit power of base stations is a complex task, if energy efficiency is also considered, even in the case when all traffic characteristic of the area are known. In my analysis, the total energy consumption of the network is calculated as the sum of the fix power of base stations and the consumption depending on the emitted power.

In my thesis I have analyzed the relation of real data-rate and energy consumption. These calculations can help in the designing of energy-efficient, high speed networks, and can also be guidelines to make the existing cells more efficient.


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