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Abstract-This paper details a new orthogonal-frequency-division-multiplexing (OFDM) modulator based on the use of a pseudorandom postfix (PRP)-OFDM and discusses low-complexity equalization and channel estimation/tracking architectures. The main property of this new modulation scheme is the ability to estimate and track the channel variations semi-blindly using order-one statistics of the received signal. Compared with known cyclic prefix OFDM (CP-OFDM) pilot-symbol-assisted modulation (PSAM) schemes, the pilot overhead is avoided: The channel estimation is performed based on the exploitation of pseudorandomly weighted postfix sequences replacing the guard interval contents of CP-OFDM. PRP-OFDM is shown to be of advantage if the target application requires 1) a minimum pilot overhead, 2) low-complexity channel tracking (e.g., high mobility context), and 3) adjustable receiver complexity/performance trade-offs (available due to the similarities of PRP-OFDM to the zero-padded OFDM (ZP-OFDM) modulation scheme) without requiring any feedback loop to the transmitter.

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Abstract-This contribution presents spectrum occupancy measurements which have been performed during the 2006 Football World Cup in Germany, in the cities of Kaiserslautern and Dortmund. The measurements investigate the time-variation of powers in 2G bands (900MHz and 1800MHz), a spectrum bandwidth including 3G bands and an ISM band (2000-2600MHz), and a global band (400-2600MHz), on the day prior to a match, the day of the match, and during the match. The first intention is to study changes in power levels and subsequently relate this to specific events, such as (i) the start of the match, (ii) half-time, and (iii) the end of the match. A next intention is to investigate the autocorrelation structure of changes in power levels, and relate this to the ease with which dynamic spectrum allocation might be performed. The results that ensue are used to inspire a discussion as to how dynamic spectrum allocation and short-range localized solutions such as IEEE 802.11 basestations might be leveraged to bolster capacity at large-scale events.