Combined Queue Management and Scheduling Mechanism to Improve Intra-User Multi-Flow QoS in a Beyond 3,5G Network

Combined Queue Management and Scheduling Mechanism to Improve Intra-User Multi-Flow QoS in a Beyond 3,5G Network

Amine Berqia (University of Algarve, Portugal), Mohamed Hanini (Hassan I University, Morocco) and Abdelkrim Haqiq (Hassan I University, Morocco)
DOI: 10.4018/jmcmc.2012010105
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Packet scheduling and buffer management are the two important functions adopted in networks design to ensure the Quality of Service (QoS) when different types of packets with different needs of quality share the same network resources. The Packet scheduling policy determines packet service priorities at the output link, it can reduce packet delay and delay jitter for high-priority traffic. The buffer management involves packet dropping and buffer allocation. The overall goal of such schemes proposed in High Speed Downlink Packet Access (HSDPA) is to take advantage of the channel variations between users and preferably schedule transmissions to a user when the channel conditions are advantageous; it does not take in consideration the characteristics of the flows composing the transmitted traffic to the user. This paper compares two queue management mechanisms with thresholds applied for packets transmitted to an end user in HSDPA network. Those mechanisms are used to manage access packets in the queue giving priority to the Real Time (RT) packets and avoiding the Non Real Time (NRT) packets loss. The authors show that the performance parameters of RT packets are similar in the two mechanisms, where as the second mechanism improves the performance parameters of the NRT packets.
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2. Packet Scheduling In Hsdpa

The High Speed Downlink Packet Access (HSDPA) was introduced in release 5 of UMTS in order to support the increasing demand for the multimedia applications that require high data rates (Zigmun & Marc, 2007). HSDPA defines a new physical channel, the High Speed Downlink Shared Channel (HS-DSCH) on which data traffic is transmitted. To improve system capacity, HSDPA adopts the advanced technologies, such as Adaptive Modulation and Coding (AMC), Hybrid Automatic Request (HARQ), fast Packet Scheduling, and an advanced receiver design. These features are tightly coupled and enable the transmission parameters to be adapted to the instantaneous variations of radio channel quality as discussed in Dottling et al. (2002) and Jo et al. (2008).

In addition to the physical layer features introduced in the HSDPA, another change is implemented to support fast packet transfer, the packet scheduling functionality is relocated from the Radio Network Controller (RNC) to the Medium Access Control (MAC) layer in the NodeB. This allows advanced packet scheduling techniques.

The wireless packet scheduler is a key element of HSDPA that determines the overall behavior of the system.

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