摘要:
A method and apparatus increase a maximum available bit rate on a single data link, in order to gain capacity within single cells. An orthogonal frequency division multiplex signal is filtered by a pulse shaping operation so as to suppress side lobes of the signal. This pulse shaping introduces known inter symbol interference (ISI) and loses orthogonality between subcarriers. However, a receiver utilizes the idea of overcoming ISI by applying equalization to the signal such that the loss of orthogonality is overcome.
摘要:
A random access protocol system and method for communicating between a mobile station and a base station in a multi-access digital radio communication system, including the steps of cyclically repeating a random access sequence and transmitting each cyclically repeated random access sequence in an orthogonal frequency division multiplex format from the mobile station as an uplink transmission.
摘要:
A method of a mobile radio system for synchronization a transmitter and receiver. The system relates to MC/DS-CDMA-system. In the system information is transmitted digitally in frames. For that purpose a data channel, a pilot channel and a synchronization channel are created. In the data channel the data blocks D0, D1, D2 etc are separated by a guard space .DELTA.. In the pilot channel, respective the synchronization channel, the information is arranged in blocks which are synchronous with each other. The repeating distance, A, of the pilot channel, corresponds to the length of one of the data blocks D0, D1, D2 etc. The repeating distance for the synchronization channel is S, corresponding to a number of blocks in the data channel. In the synchronization channel information is introduced into the blocks which indicates their relation to the data channel. The method in this way allows an identification of the position of the pilot channel, which indicates the position of the synchronization channel, at which a decoding of the information of the the synchronization channel appoints the position of the data channel.
摘要:
A multi-user system includes radio channels which are independent and uncorrelated for different users. The system operates with frequencies which, due to multi-path propagation, are more or less attenuated for one user and more or less amplified for another user. Elements are arranged to detect or measure the attenuation/amplification for the different frequencies. The elements also prevent signal or information transmission at frequencies which drop below a predetermined lowest attenuation by disconnecting the frequency or frequencies in question and connecting a corresponding number of frequencies which pass the attenuation value criterion.