Scheduling Algorithms and QoS in HSDPA
Independent thesis Advanced level (degree of Master (Two Years))Student thesisAlternative title
Scheduling Algorithms and QoS in HSDPA (Swedish)
High Speed Downlink Packet Access (HSDPA) is the extension to the Universal Mobile Telecommunication System (UMTS). HSDPA allows for higher data rates due to new adaptive Modulation and Coding (AMC) techniques, Hybrid Automatic Repeat reQuest (H-ARQ) and fast scheduling algorithm. One of the key features of HSDPA technology is to handle UMTS traffic classes with different Quality of Service (QoS) requirements. In order to provide QoS several scheduling algorithms, QoS control constraints, and different other schemes have been proposed in literature. In the thesis, a simple matlab based model for HSDPA is presented in order to simulate various algorithms. The QoS controls in terms of guaranteed bit rate (GBR) have been implemented by means of barrier functions which perform barrier around the feasible region. The results illustrate the trade-off between the cell throughput and the minimum guaranteed bit rate. Traffic classes are prioritized by means of QoS parameters. The priority is given to RT traffic streams over interactive services. Real-Time (RT) algorithms have been simulated to prioritize traffic classes based on delays.
QoS is the ability to provide resources and prioritize different applications. As mentioned before, the 3GPP standard defines four categories of service (Conversation, streaming, interactive and background) for UMTS. Strategies in traffic management, priority GBR allowances and bandwidth are important strategies for traffic differentiation and quality of service (QoS). Providing QoS over HSDPA is one of the challenging tasks for researchers. The significant results and findings of our thesis are as follows • In this thesis various algorithms were implemented with their duties barrier to provide guarantees of quality, in terms of speed guaranteed (GBR). The emphasis was to ensure the flow and priority categories of traffic. First the performance of algorithms were studied alone and then along with the barrier functions. It is concluded that barrier functions play an important role by means of providing QoS guarantee in HSDPA, considering channel conditions. Traffic classes were prioritized on QoS parameters defined for barrier functions. It was found that minimum bit rates were maintained by barrier functions but the cell throughput decreases with their barrier functions depending upon QoS parameters. The streaming aware scheduler has been evaluated by means of simulations in mixed scenarios and it is concluded that this algorithm protects streaming QoS in high overload conditions. It is therefore concluded that barrier functions and streaming aware schedulers are the best option for QoS control. These schedulers are very simple and consider diversity gains as well.
Place, publisher, year, edition, pages
2009. , 73 p.
HSDPA, QoS, Scheduling Algorithms
IdentifiersURN: urn:nbn:se:bth-1181Local ID: oai:bth.se:arkivex623515F9C88E5605C12576C600275EFFOAI: oai:DiVA.org:bth-1181DiVA: diva2:828343