Martin Döttling

Hybrid ARQ and adaptive modulation and coding schemes for high speed downlink packet access

A major evolution of the UMTS standard is the so-called high speed downlink packet access (HSDPA) mode, which provides peak data rates of 10.8 Mbps. Key enabling technologies include fast scheduling, adaptive modulation and coding (AMC), as well as hybrid automatic repeat request (HARQ). The paper gives a general overview of the current HSDPA standard. Special focus is put on the implementation and performance of the AMC and HARQ functions, as well as on their interworking. The performance of different HARQ schemes are compared for QPSK and 16-QAM and varying code rates. Subsequently, link-level throughput is simulated. It is shown that the throughput gains offered by advanced HARQ schemes depend on the performance of the AMC function. In particular, the gain offered by incremental redundancy techniques increases with increasing errors in selecting the appropriate modulation and code rate.

Incremental redundancy and bit-mapping techniques for high speed downlink packet access

A major evolution of the UMTS standard is high speed downlink packet access (HSDPA), which provides higher cell throughput and peak data rates of 10.8 Mbps. Key enabling technologies include fast scheduling, adaptive modulation and coding (AMC), as well as hybrid automatic repeat request (HARQ). To ease the implementation of HSDPA all coding elements are identical to standard WCDMA. In particular, the rate 1/3 turbo code is reused and no trellis coded modulation scheme has been introduced. The resulting drawbacks are analyzed and it is shown how they are efficiently counteracted by bit-mapping techniques accounting for the different bit reliabilities within a 16-QAM symbol. This paper focuses on the implementation and performance of HARQ and bit-to-symbol mapping functions. The performance of different HARQ schemes is compared for QPSK and 16-QAM and varying code rates. It is shown that depending on the code rate and the user terminal capabilities different HARQ types are favorable.

Efficient channel quality feedback schemes for adaptive modulation and coding of packet data

Adaptive modulation and coding (AMC) is a powerful technique to improve throughput especially of wireless packet-oriented channels. In general such link adaptation schemes rely on feedback from the receiver, which allows selecting the appropriate modulation and coding. In this paper we evaluate the performance of different channel quality feedback schemes and propose a general performance metric, that considers data throughput, energy efficiency, channel resource consumption, as well as control overhead. At the example of the high speed downlink packet access (HSDPA) channel for UMTS FDD, we show that channel quality feedback schemes that consider the burstiness of packet data are able to provide notably higher efficiency than the cyclic feedback currently standardized.

Integration of Spatial Processing in the WINNER B3G Air Interface Design

Numerous investigations of spatial processing algorithms are available in literature showing the benefit of MIMO systems in particular situations. From a system perspective, however, spatial processing has to provide adaptivity and scalability to a wide range of scenarios and has also to be seen in the context of its impact on other system services and functions, its enabling requirements, overhead, and robustness. This paper summarizes recent work towards integrated spatial processing services and functions for an OFDM-based B3G air interface, developed in the European IST research project WINNER. The current status of the air interface and the multi-user spatial domain link adaptation concept is summarized. A baseline spatial scheme selection process is developed as part of the overall MAC radio resource control

WINNER - Towards Ubiquitous Wireless Access

The huge growth in wireless communication has led to a wide range of technologies each addressing a particular scenario or need. The goal of the WINNER project is to develop a single new ubiquitous radio access system concept to address the whole spectrum of mobile communications scenarios. This paper surveys the challenge of providing ubiquitous operation and introduces the key technologies investigated in WINNER to meet these needs

A multi-user spatial domain link adaptation concept for beyond 3G systems

This paper summarizes current work within the IST-Project WINNER (Wireless World Initiative New Radio) towards a spatial processing solution as an integral part of the overall system concept. Major requirements for the WINNER multi-antenna concept include high performance, robustness, and adaptation to a wide range of scenarios and terminal classes, as well as efficient interworking with the basic transmission and network concept. Based on these guidelines, a first proposal for the WINNER multi-antenna concept is elaborated upon and presented in the form of a generic downlink transmitter that will serve as baseline for further investigation and system integration