1. Field of the Invention
The present invention relates to wireless communications; in particular, using multiple carriers to provide access to a wireless communication system.
2. Description of the Related Art
Accessing a wireless communication network requires that a mobile communication device receive information transmitted from a base station on several channels. For example, the pilot channel identifies the base station and provides timing to the mobile unit, the synchronization channel provides the mobile unit with information used to locate other channels such as a paging channel, a broadcast control channel (BCCH), and a forward common control channel (FCCCH). In older communication systems, such as systems that follow the TIA standard IS-95A or B, the paging channel provides the mobile unit with information on how to make voice or data calls and it also informs the mobile of incoming calls. In newer systems such as systems that follow TIA standard IS-2000 revision A, the BCCH informs the mobile of how to initiate a voice or data call, and the FCCCH informs the mobile of incoming calls. These different standards have evolved as technology has advanced and sometimes make it difficult to configure networks so that both the newer mobiles conforming to the newer standard and the older mobiles conforming to the older standards can access the communications network.
Such a problem exists with regard to messages carried on the synchronization channel. As the standards have changed, the length of messages carried on the synchronization channel has increased. For example, synchronization messages under the IS-95B standard contain 26 octets, and synchronization messages under the IS-2000B standard are variable in length and may be greater than or equal to 28 octets long. Unfortunately, some older mobiles have difficulty interpreting a synchronization message if it is longer than expected. For example, some older mobiles cannot interpret synchronization messages that are longer than 27 octets, and yet another group of older mobiles cannot interpret synchronization messages that are longer than 28 octets. As a result, it is necessary to provide a flexible synchronization messaging format that can be used by different types of older mobiles, while offering the newer mobiles all the advantages provided by the newer technology contained in the newer standards.