In this paper, we present real-time broadband multi-user multi-antenna measurements in typical indoor and outdoor scenarios. For the first time, essential frequency-selective functions of a new medium access control (MAC) layer, namely fair resource assignment to multiple users, spatial mode selection and adaptive modulation, have been implemented in real-time on standard digital signal processing hardware. The new MAC layer is steered over wireless feedback and control channels in a closed loop manner. Our implementation uses parameters close to the forthcoming long-term evolution (LTE) of the 3G air interface, thus illustrating the feasibility of the new functions in next-generation cellular radio systems. The paper describes our real-time implementation and reports several test results. Benefits of the frequency-selective multi-user MIMO MAC are validated in realistic mobile propagation environments.

In this paper we report the first real-time measurements of a 3GPP-LTE multiple antenna system in typical indoor and outdoor scenarios. In a single cell, single user scenario we demonstrate throughput exceeding 100 Mbit/s with a 2times2 MIMO configuration. This throughput gain is significant as compared to existing single antenna systems. We describe the basic LTE system design and prototype ingredients which were implemented to achieve these results. The highlight of our MIMO-OFDM system design is frequency dependent link adaptation. In principle, we show that this parallel link adaptation provides robust gains in a cellular broadband system. The robustness is seen in both our indoor and outdoor measurement results. The key feature of our work is implementation of multiple antenna concepts in such a broadband system.

We demonstrate how virtual MIMO techniques can be implemented in a next-generation mobile communication system. In order to test basic principles, joint spatiotemporal processing of two users has been implemented in an uplink scenario. A prerequisite of virtual MIMO is accurate synchronization. It is shown that the carrier frequency offset can be reduced to a few Hz only at small signal-to-noise ratios. Based on remote synchronization via the downlink, a technique called frequency advance is applied in the uplink, i.e. the terminals correct their frequency offsets in the digital baseband prior to data transmission. The principle has been implemented and tested in real-time using system parameters of the long term evolution (LTE) of the 3 generation (3G) of cellular systems. Two user’s signals have been successfully detected on the same radio resource.

This article provides an overview of ongoing research within the framework ScaleNet. Considering IP as the basis transport scheme, the wireless and the wireline world have just started to move towards each other. ScaleNet is pushing this development by evolving a new system concept and by developing technologies for Fixed & Mobile Convergence.

Broadband networks using wireless transmission techniques are a quick and flexible means of implementing subscriber access. Unoccupied frequency bands with sufficient bandwidth to allow the transmission of digital signals at very high bit rates are found only in the microwave bands. Because the path loss is fairly high at these frequencies, the diameter of radio cells is limited to a maximum of a few kilometres. This results in a microcellular system, which is best implemented in the form of a point‐to‐multipoint system, where one radio‐base station serves all subscribers registered in that radio cell. An interactive, broadband, ATM‐based radio local loop has undergone successful trials in Munich. Copyright © 2001 John Wiley & Sons, Ltd.

The BMBF founded project COVERAGE investigates broadband access to the IP core-net in public or semipublic hot spot scenarios for mobile users. The basis for our investigations are OFDM-systems (Orthogonal Frequency Division Multiplex) like H/2 (HiperLAN/2) or IEEE802.11a which provide data-rates up to 54 Mbit/s. Main topic of COVERAGE are multihop networks as a means to increase the access area of H/2 radio cells. Unfortunately the performance of multihop networks with respect to throughput decreases rapidly with the number of so called EPs (Extension Point) as intermediate hop devices. One reason is the protocol overhead of H/2. For single APs this protocol overhead can be accepted, while in a multihop network this overhead is required once for each additional EP. Here we propose a suitable combination of a DLC protocol with sector antennas and SFN (Single Frequency Network) concepts, which reduces the overall protocol overhead.

This paper focuses on a CDMA radio link with a 'turbo-decoding' (TD) scheme. The radio link concept is based on the requirements for third generation mobile radio communications. The performance of the CDMA link is evaluated for ATM service scenarios with 32 kbit/s low-delay speech and 64 kbit/s data transmission. For this reason, Monte-Carlo simulations based on measured mobile radio impulse responses are performed. As a reference to which TD can be compared, a one-dimensional convolutional code with soft-decision Viterbi decoding (VD) is alternatively used. The simulation results show that a single coding scheme with TD may be advantageously applied for data as well as for low-delay speech services.