Edgar Bolinth

A blockwise loading algorithm for the adaptive modulation technique in OFDM systems

The OFDM transmission technique has the inherent flexibility to adapt the modulation scheme on each subcarrier according to the reception quality, i.e. the signal-to-noise ratio (SNR) on a subcarrier. The allocation of bits to subcarriers is performed by so-called loading algorithms. In this paper, a new and rather simple loading algorithm is introduced which shows comparable performance and lower computational complexity compared to the well-known algorithm of Chow et al. (1995). In the proposed algorithm, subcarriers are clustered in blocks, which are allocated the same modulation scheme. This way, the signalling overhead can be reduced in comparison with standard subcarrier bit loading algorithms.

BRAIN—an architecture for a broadband radio access network of the next generation

The tremendous growth rates of the Internet as well as the area of mobile communications give rise to the chance that the mobile Internet is most promising by combining both the Internet and mobile communications. These prospects are the motivation for the European research project BRAIN (Broadband Radio Access for IP-based Networks), which is developing an open architecture for a broadband wireless mobile access network offering an integrated communication platform across heterogeneous networks and, thus, goes beyond current third generation systems and towards the mobile Internet. The project covers three major technical areas: support of seamless service provision in a mobile environment; the design of an IP-based access network that will support non-cellular technologies such as wireless LANs; and requirements of a broadband air interface suitable for hot spots. BRAIN is going to integrate HIPERLAN/2 with UMTS by means of an IP access network. The work is guided by a user-centric top-down approach ensuring that user functionality is the key driver of the project. This article will focus on that part of the BRAIN work which specifies the main interfaces of the BRAIN architecture and deals with aspects related to the support of Quality of Service and mobility. Copyright

Low-Complexity Finger-Wise Interference Cancellation for Rake Receivers with Receive Diversity

Todays mobile communications systems are usually interference limited in terms of their overall capacity. In the paper we present a novel powerful yet simple interference cancellation algorithm for receive diversity systems. The algorithm for Rake receivers is based on the correlation between the identical multi-path delays occurring on the antennas. The attractive simplicity is due to the separate handling of different Rake fingers yielding a low complexity with the lack of large matrices. Nevertheless, the new algorithm exhibits an excellence performance, which is proven by simulation results.