BCH,CCCH and DCCH Channel of GSM BCH (Broadcast Channels) BCCH(Broadcast Control Channels) Downlink Only. Broadcast information of the serving cell (System Information). Transmitted on timeslot zero of BCCH carrier. Read only by idle mobile at least once every 30 secs. SCH (Synchronization Channels) Downlink Only Carries information for frame synchronization. Contains frame number and BSIC … Read more
Basic of GSM Um,Abis and A Interface GSM (Um) Air Interface This is the interface between the GSM mobile station and the GSM Base station. The Air interface (RF Interface) uses the Time Division Multiple Access (TDMA) technique to transmit and receive traffic and signaling information between the GSM BTS and GSM Mobile Station. The … Read more
If it is available, the second cell site returns the Walsh Code that will be assigned for the soft handoff. At this point, the original base station orders the soft handoff by using a handoff direction message on the traffic channel using one of the two types of signaling: dim and burst or blank and … Read more
Once a call is established, the mobile is constantly searching for other possible cell sites that might be good candidate for soft handoffs. Most of the search time is limited to looking for those PN offsets specified in the neighbor list found on the paging channel. The rake receiver’s searcher is the device that scans … Read more
After each access attempt, the mobile listens to the Paging Channel for a response from the base station. If the base station detects the access probe from the mobile, it responds with a channel assignment message. This message contains all of the information required to get the mobile onto a traffic channel. this messages includes … Read more
The user then decides to make a call. The number is keyed in and the send key is hit. This initiates an Access Probe. The mobile uses a special code channel called the Access Channel to make contact with the cell site. CDMA mobiles can transmit two types of channels on the single physical channel … Read more
What is inside PAGING Channel Message in CDMA The paging channel is the heart of a CDMA base station. All of the parameters and signaling necessary for the proper operation of a CDMA cell site are handled by the paging channel. The paging channel supports a number of distinct messages that provide information and send … Read more
The sync channel messages include the CDMA protocol revision supported by the cell site, the minimum protocol revision supported by a CDMA mobile in order to work with the cell site, the system and network identification numbers for the cell site, the PN offset of the cell site, the paging channel data rate, and all … Read more
System Access: When the mobile first turns on, it must find the best base station. This is similar to analog where the phone scans all the control channels and selects the best one. In CDMA, the mobile unit scans for available Pilot signals, which are all on different time offsets. This process is made easier … Read more
The original release of the EIA/TIA-95-B standard defined the protocol messages and formats to be used in the CDMA system. This release is know as Revision 0 of the IS-95 standard. Since the release of Revision 0, a newer standard has been released for cellular CDMA that is called the Revision A standard of IS-95. … Read more