MBMS—IP Multicast/Broadcast in 3G Networks

In this article, the Multimedia Broadcast and Multicast Service (MBMS) as standardized in 3GPP is presented. With MBMS, multicast and broadcast capabilities are introduced into cellular networks. After an introduction into MBMS technology, MBMS radio bearer realizations are presented. Different MBMS bearer services like broadcast mode, enhanced broadcast mode and multicast mode are discussed. Streaming and download services over MBMS are presented and supported media codecs are listed. Service layer components as defined in Open Mobile Alliance (OMA) are introduced. For a Mobile TV use case capacity improvements achieved by MBMS are shown. Finally, evolution of MBMS as part of 3GPP standardization is presented

Spectrum management and radio resource management considering cognitive radio systems

International fora and some national administrations define a cognitive radio (CR) as a pioneering radio communication system that would be capable of altering and adapting its transmitter and receiver parameters based on communication and the exchange of information with related detectable radio communication systems. It is crucial for the acceptance of CR that the CR radio emissions do not impact the performance of incumbent radiocommunication systems. Possible co-existence techniques can be divided into collaborative and non-collaborative methods where the former allow a limited amount of communication between the incumbent systems and the CR, and the latter require autonomous operation of the CR network. In the non-collaborative techniques, the CR has to detect and avoid the transmission channels of the incumbent systems. Since the signal levels can be rather low, in particular when spread spectrum techniques are used, and because errorneous conclusions can be drawn due to shadowing and multi-path fading (the hidden node problem), it is not recommended that CR techniques are deployed in bands where interference sensitive or licensed QoS operations are generally used