Among several first mile solutions proposed so far, the key advantage of the IEEE 802.16 standard, widely known as WiMAX, is to ensure large area coverage and rather inexpensive equipment at the subscriber side. Modern requirements to wireless connectivity include mandatory QoS guarantees for a wide set of real-time applications: this is the case of the ever growing trend of VoIP calls. To this aim, WiMAX supports natively real-time traffic. In this paper, we report on the results of measurements performed on a WiMAX Alvarion testbed, located in Turin, Italy. In particular, through synthetic VoIP traffic generation, we obtained the corresponding Emodel figures, thus tracing the system operation intervals.
This chapter describes a set of spectrum sensing algorithms to be employed for the detection of OFDM-based (Ortogonal Frequency Division Multiplexing) transmissions in the TV bands (470-790 MHz) i.e. DVB-T channels. Spectrum sensing techniques take a crucial role to support geo-referenced TV White-Spaces (TVWS) databases and to maintain them up-to-date over time. When considering a single-antenna spectrum sensing unit, very effective methods for detecting OFDM signals are based on DVB-T Cyclic Prefix and pilot pattern feature detection. Starting from these, further improvements can be made using multi-antenna techniques. This Chapter shows performance analysis of feature-based single-antenna and multiantenna techniques in order to derive trade-offs and conclusions.
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