1. |
|
|
2. |
|
|
3. |
|
|
4. |
|
|
5. |
|
|
6. |
|
|
7. |
|
|
8. |
- Folke, Mats, et al.
(author)
-
On the TCP minimum retransmission timeout in a high-speed cellular network
- 2005
-
In: Proceedings of the Eleventh European Wireless Conference.
-
Conference paper (peer-reviewed)abstract
- HS-DSCH is a high-speed shared radio channel extension for WCDMA which is used for cellular mobile telephony. The algorithm for distributing the channel resources together with the characteristics of the radio medium result in delay variations. The TCP minimum retransmission timeout interval has effectively alleviated delay variations in its range from deteriorating TCP performance. But recently, this bound has been shortened in modern widely spread TCP implementations. The aim of our study is to find out how a shorter minimum retransmission timeout affects TCP performance over HS-DSCH. We have implemented a model of HS-DSCH in the network simulator ns-2. Our simulations cover a wide range of different minimum retransmission timeout settings and loads, two types of schedulers (Round-Robin and Signalto-Interference-Ratio (SIR) scheduling) and two versions of TCP (SACK and NewReno). Our results show that the number of spurious timeouts increase with the load. The SIR scheduler causes fewer spurious timeouts than the RR scheduler for shorter minimum retransmission timeout settings, however, for longer settings the RR scheduler causes fewer spurious timeouts compared to the SIR scheduler. The minimum retransmission timeout has consequences for goodput fairness, but it does not affect the total system throughput. Both TCP versions produced similar results.
|
|
9. |
- Folke, Mats, et al.
(author)
-
Scheduling support for mixed VoIP and web traffic over HSDPA
- 2007
-
In: 2007 IEEE 65th Vehicular Technology Conference. - Piscataway, NJ : IEEE Communications Society. - 1424402662 ; , s. 814-818
-
Conference paper (peer-reviewed)abstract
- HSDPA (high-speed downlink packet access), introduced in WCDMA release 5, provides a high-bandwidth shared channel with short transmission time interval (TTI). The short TTI together with appropriate scheduling enable HSDPA to support efficient multiplexing of traffic. We explain the performance of four scheduling algorithms when transmitting a traffic mix consisting of both conversational (VoIP) traffic and background (Web) traffic over the high-speed downlink shared channel (HS-DSCH) of HSDPA. We consider both cell throughput and user satisfaction. The proportional fair (PF), the maximum rate (MR) scheduler and two extended versions of MR, are tested for different VoIP scheduling delay budgets and varying load. To understand the behaviour of the schedulers, we use the ns-2 simulator extended with a model of HS-DSCH to simulate a mixed traffic scenario. Our results show that a scheduler that gradually increases the VoIP priority and considers the user's current possible rate, performs well. A more drastic increase in VoIP priority is however needed when the delay budget is short. Furthermore, attempting to uphold quality for both VoIP and Web traffic makes the system sensitive to overload situations.
|
|
10. |
|
|