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3G High Speed Downlink Packet Access performance in Mobile Internet connections
UMTS, the Universal Mobile Telecommunication System, allows for packet based Internet connections. The first two releases provides with so-called dedicated channels with data rates up to 384 kbps for wide-area coverage. However, the actual throughput of these dedicated channels will be poor if the radio block error rate is allowed to be high. The problem is that the Internet¿s Transmission Control Protocol (TCP) is optimised for reliable wired links, and performs with dissatisfaction when there are high delays, delay variations, packet reordering or packet losses. Moreover, the investment required to build a UMTS network with high capacity and that supports high bit rate Internet services using radio bearers with low error rates is very high. Hence, a reduction of the error rate should only be a temporary solution when the number of users is low, i.e., during a low capacity requirement.
HSDPA, High Speed Downlink Packet Access, is a concept that has been developed to enhance UMTS packet data performance. It consists of a new High Speed Downlink Shared Channel (HS-DSCH), which is shared between many users. The aim is to increase the performance of packet data services by increasing bit rates, reducing delay and efficiently scheduling users. Peak data rates more than 8 Mbps can be achieved. Because of faster and less retransmissions, shorter delay and the possibility of scheduling, we believe that with HS-DSCH it should be possible to mitigate many of the problems that TCP introduce on dedicated channels.
This Masters Thesis Work will investigate and evaluate the performance of TCP traffic over HS-DSCH. The main objectives of the work are:
· Construct a model of the HS-DSCH. This is an important part of the thesis work and good programming skills are therefore required.
· Evaluate TCP¿s performance over HS-DSCH by traffic flow simulations.
· Analyse the results and compare them with the dedicated channels performance. Identify any throughput problems that may arise and suggest solutions that improve performance.
Anders Dahlén, 08-713 51 37, [email protected]
Per Ernström, 08-713 81 34, [email protected]
Ulf Nilsson, 08-713 82 64, [email protected]
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