The new digital radio system DAB (Digital Audio Broadcasting, nowadays often called Digital Radio) is a very innovative and universal multimedia broadcast system which will replace the existing AM and FM audio broadcast services in many parts of the world in the future. It was developed in the 1990s by the Eureka 147/DAB project. DAB is very well suited for mobile reception and provides very high robustness against multipath reception. It allows use of single frequency networks (SFNs) for high frequency efficiency.
标签： Broadcasting Principles Digital Audio
上传时间： 2020-05-27
上传用户：shancjb
Many wireless communications channels consist of multiple signal paths from the transmitter to receiver. This multiplicity of paths leads to a phenomenon known as multipath fading. The multiple paths are caused by the presence of objects in the physical environment that, through the mechanisms of propagation, alter the path of radiated energy. These objects are referred to as scatterers. In the past, researchers often looked at ways to mitigate multipath scattering, such as in diversity systems. Multiple-input, multiple-output (MIMO) systems, on the other hand, use multipath diversity to their advantage; a MIMO system has the ability to translate increased spatial diversity into increased channel capacity.
标签： Multiple-Output Multiple-Input Channel Models
上传时间： 2020-05-31
上传用户：shancjb
Orthogonal frequency division multiplexing (OFDM) has been shown to be an effective technique to combat multipath fading in wireless channels. It has been and is going to be used in various wireless communication systems. This book gives a comprehensive introduction on the theory and practice of OFDM for wireless communications.
标签： Multiplexing Orthogonal Frequency Division
上传时间： 2020-05-31
上传用户：shancjb
Radio propagation measurements and channel modelling continue to be of fundamental importance to radio system design. As new technology enables dynamic spectrum access and higher data rates, radio propagation effects such as shadowing, the presence of multipath and frequency dispersion are the limiting factors in the design of wireless communication systems. While there are several books covering the topic of radio propagation in various frequency bands, there appears to be no books on radio propagation measurements, which this book addresses at length.
标签： Propagation Measurement Radio
上传时间： 2020-06-01
上传用户：shancjb
Wireless communications has become a field of enormous scientific and economic interest. Recent success stories include 2G and 3G cellular voice and data services (e.g., GSM and UMTS), wireless local area networks (WiFi/IEEE 802.11x), wireless broadband access (WiMAX/IEEE 802.16x), and digital broadcast systems (DVB, DAB, DRM). On the physical layer side, traditional designs typically assume that the radio channel remains constant for the duration of a data block. However, researchers and system designers are increasingly shifting their attention to channels that may vary within a block. In addition to time dispersion caused by multipath propagation, these rapidly time-varying channels feature frequency dispersion resulting from the Doppler effect. They are, thus, often referred to as being “doubly dispersive.”
标签： Time-Varying Channels
上传时间： 2020-06-01
上传用户：shancjb
