We show that measurements of time-varying mobile radio channels obtained with uncalibrated correlative channel sounders are affected by four different types of systematic errors (commutation, pulse-compression, aliasing, and misinterpretation error). We analyze these errors and provide upper error bounds that are formulated in terms of channel and sounder parameters. Based on these error bounds, we provide guidelines for a judicious choice of important sounder parameters. Computer simulations using a simple two-path channel illustrate our theoretical results. Finally, we show how our results can be used to assess the accuracy of measured channel data.

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Abstract. Broadband IP-based multimedia services are rapidly growing and there is the trend to use these services everywhere. Due to the fact that passengers in long distance high speed trains have a very comfortable environment to use their own terminal equipment, e.g. laptops with IEEE802.11×WLAN capability, it seems to be very promising to deliver broadband internet into trains. The challenge is the land-train connection where a high bit data rate link, e.g. 1 Mbps in average in up-and downlink, has to be provided to enable several users within the train broadband internet access at the same time even at high speeds of the train. This paper describes a systematic approach starting at basic propagation measurements in a typical train environment and ending up with lab investigations by means of hardware channel simulation for different existing radio technologies which are candidates for the land-train connection.

Future mobile radio networks are expected to witness an increase in capacity demand. Since the spectrum suited for mobile radio application is scarce, the spectrum efficiency of future mobile radio networks has to be increased in order to be able to meet the capacity demand. In networks applying adaptive modulation and coding, both, transmit power and bandwidth can be considered as resources. In order to achieve high spectrum efficiency, the adaptation of the allocation of transmit power and bandwidth to the time-varying capacity demand is an important topic. In this paper, an approach that adjusts the allocation of transmit power to the cells in order to adapt the network to changing capacity demands is proposed. A mathematical model that relates transmit power and the probability of outage in the cells is presented and used in an approach for the minimsation of the outage probability in the cells using convex optimisation techniques. The performance of the presented approach is evaluated and its suitability for the adaptation of the network to capacity hotspots is shown. Due to the use of a mathematical model and convex optimisation techniques, the presented approach is suited for self-organising optimisation.