| 摘要 |
In a cellular communications system (10) in which a plurality of mobile subscriber units (100) attempt to access at least one BTS (140), which is controlled by a controller (150), a method of controlling system congestion is provided. The subscriber units (100) record a number of failed access attempt transmissions (210). The failed attempt data (122, 124) is transmitted (220) to the BTS (140) in subsequent access messages (120). From the failed attempt data (122, 124), the controller (150) generates an array of access restriction values (172), which are transmitted to the subscriber units (100) within the Access Parameters Message (170). The access restriction values (172) are used by the subscriber units (100) to perform one or more persistence tests (240, 245, 250). The access restriction values (172) control the probability of the persistence tests (240, 245, 250) passing for any given access slot. The present method provides dynamic control of system load, allowing for a higher percentage of successful call attempts when the system (10) is experiencing a heavy load.
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