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The recording performance of a new magnetic tape based on ultra-fine, perpendicularly-oriented BaFe particles was investigated. Specifically, using a low lateral tape motion demonstration platform, a new servo pattern written on the advanced perpendicularly oriented BaFe medium, a new low friction head technology, a novel synchronous servo channel design, and advanced servo control concepts, we were able to demonstrate a record closed-loop track-follow performance with a 23.4 nm standard deviation of position-error signal, roughly one order of magnitude better than in current tape products. In addition, using read back waveforms captured on the same advanced perpendicularly oriented BaFe medium with a 0.2-m-wide data reader, we demonstrated write/read performance at 518 kbpi using advanced noise-predictive maximum likelihood (NPML) detection schemes. Combining these two results, we estimate that the new medium can support an areal recording density of up to 29.5 Gb/in 2 . This result demonstrates the scalability and extendability of tape technology using low-cost particulate media.

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In this paper a novel link adaptation algorithm is proposed that is capable of adjusting the transmit power level and the data rate jointly to the radio channel conditions. The proposed method relies solely on link quality information available at the transmitter by employing the reception or non-reception of the acknowledgment frames as a measure of the channel quality with respect to the power level and data rate. The method is fully compatible with the 802.11 wireless LAN standard. In contrast to many other proposals, it neither relies on the RTS/CTS protocol nor requires a feedback channel to transmit link-quality estimates from the receiver to the transmitter. Different strategies for optimizing the data rate and power level are given. These depend on the scenarios considered, the number of active stations, and the service requirements. The two main strategies are either to drive the system towards the highest possible data rate and adjust the rate and power levels accordingly (''high-performance'' mode) or to focus on power saving, possibly trading this for other performance criteria such as throughput or delay performance (''low-power'' mode). Other special cases, such as power or rate only adaptation, are also discussed. It can be shown that in most cases the best choice for achieving low transfer times, maximizing throughput, and alleviating the hidden terminal problem is to transmit at the highest possible rates and with high power levels. This ''highperformance'' mode of operation also minimizes the transmission times, which in turn maximizes the time for putting idling components into a sleep mode, thereby minimizing the overall power consumption.

Space-time receivers for wireless communication systemsoffer the possibility to have both TIX-and RX-antennas.For a realistic simulation of such systems, a multiple input multiple output (MIMO) spatial channel model is required which reasonably characterizes the space-and time-variant effects of the mobile radio channel. This paper describes a space-time vector channel model with realistic fading simulation for different scenarios. Mutual correlation between the fading coefficients is considered. This allows an estimation of the diversity gain, that can be achieved with spacetime receivers in direrent scenarios.tors in the far-field. For each dominant reflector one significant multipath is assumed. This path consists of a large number of incoming waves which result from the structure of local scatterers in vinicity of the transmitter and receiver. Since the relative delays of these waves are small, they cannot be resolved by the receiver. In case of any movement in the scenario the superposition of the waves results in a space-time fading process. Independent fading is assumed for each significant multipath p with a specific time delay TP.After the introduction a MIMO-signal model in Section 2 including a discrete time matrix formulation, the MIMOchannel characteristics and their modeling are described in Section 3 in more detail. In Section 4 the results of the space-time fading models are compared with theoretical assumptions.