Scheduling and Adaptive Transmission for the Downlink in 4G Systems.

Nilo Casimiro Ericsson, UU Sorour Falahati, CTH, Anders Ahlén, UU and Arne Svensson, CTH.

Future Telecommunication Conference Beijing, China, November 2001.

Also presented at the Wireless World Research Forum Workshop, Paris, France, December 2001.

Outline:

The Wireless IP project within the PCC program studies problems that are crucial in the evolution of UMTS towards high data rates, as well as in future 4G technologies aimed at rapidly mobile terminals. The goal is to attain higher througputs for packet data in particular in downlinks, without bandwidth expansion and while providing acceptable quality of service for various classes of traffic.

Abstract:

In this paper, we propose a system suitable for efficient packet data transmission using the Internet Protocols (IP) in wireless 4G systems. It consists of a hybrid type-II Automatic Repeat reQuest (ARQ) scheme combined with an Adaptive Modulation System (AMS) and a time-slot scheduler supplied by channel predictions.

This scheme is referred to as predictive HARQ-II/AMS. The performance of the system in a fast fading downlink channel is investigated through simulations where in particular, BER and throughput performance are studied.

The proposed system is compared to two simpler systems. One has access to channel predictions and uses adaptive modulation but does not employ error correction and retransmission at the link layer (referred to as predictive AMS). The other has no access to the channel prediction but uses HARQ-II/AMS in a blind way (referred to as blind HARQ-II/AMS).

The results show that with perfect channel prediction both predictive AMS and HARQ-II/AMS satisfy the BER requirements, with some advantages to the former in terms of efficient usage of channel capacity. However, with imperfect channel prediction, a retransmission protocol is required to meet the BER requirement, making predictive HARQ-II/AMS the winner.

Related publications:

Earlier VTC00-fall paper on the same topic.

Licenciate Thesis by Nilo C. Ericsson, June 2001.

Licenciate Thesis by Sorour Falahati, Feb. 2000.

VTC01-spring paper on channel prediction over 1-10 ms horizons.

Performance of 4G OFDM System based on these principles (FTC 2001, Beijing)

An overview of the Wireless IP Project, NRS 01.

Source:

Paper in Pdf, 80K