A CDMA system includes four independent subsystems: mobile station (MS), base station subsystem (BSS) and mobile switching subsystem (MSS). OMM
BSS is a general term for wireless equipment and wireless channels control equipment serving one or several cells. Usually, BSS consists of one or more Base Station Controllers (BSC) and Base Transceiver Stations (BTS).
AS the central part of cdma system, MSC serves to control the mobile stations that are within its controlling sphere, and to perform the channel switching. It functions as the interface between the mobile system and the other public telecommunication means. MSC provides the network interfaces, the charging function and the function of processing the common channel signaling. It can process the No. 7 signaling between BSS and MSC, and realizes the auxiliary radio resource management and mobile management. In addition, for the sake of establishing the calling route to the mobile station, each MSC can function as a Gateway MSC (GMSC). If a network transfers a call to PLMN, but if it cannot query HLR, then the call will route to a MSC. This MSC will query related HLR, and rout the call to the MSC where the called subscriber is located. This kind of MSC is called a gateway MSC (GMSC). Which MSCs are to be chosen as GMSC depends on the network service carrier.
The VLR is a location register used by MSC for information index. It saves and updates data of mobile subscribers who roam to this VLR service area. VLR can be built together with the MSC or set separately, in the former case, interface B turns to be an internal interface.
The HLR is a location register used for registering identity of subscribers, including subscriber information (ESN, MDN, IMSI, MIN), service information, current location and valid term, etc. HLR can be built together with the MSC or set separately. In case of the former, interface C turns to be an internal interface.
Authentication center is a functional entity for the management of authentication information related to the mobile stations. It functions to authenticate mobile subscribers, save authentication parameters of mobile subscribers and generate and send corresponding authentication parameters in response to the request from MSC/VLR. AUC can be built together with HLR or set separately. In case of the former, interface H turns to be an internal interface.
Advantages of CDMA Frequency reuse facto is 1; network design and expanding become much easier AMPS , D-AMPS , N-AMPS CDMA 30 30 10 kHz 200 kHz 1250 kHz 1 3 1 Users 8 Users 20 Users 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 3 4 4 3 2 5 6 1 7 Typical Frequency Reuse N=7 Typical Frequency Reuse N=4 Typical Frequency Reuse N=1 Vulnerability: C/I 17 dB Vulnerability: C/I 12-14 dB Vulnerability: E b /N o 6--7 dB GSM
Advantages of CDMA large coverage almost 2 times than GSM, save money for operator Example:cover 1000 km 2 ： GSM need 200 BTS ， CDMA only need 50 BTS Attention: exact result need “ Link Budget ”
Advantages of CDMA High spectrum capacity: 8--10 times than AMPS, 4—6 times than GSM FDMA---Different user use different frequency TACS 、 AMPS TDMA---Different user use different time slot of one frequency GSM 、 DAMPS CDMA---Different user use same frequency at the same time,but with different spreading code Frequency Time Power Frequency Time Power Frequency Time Power FDMA TDMA CDMA
ZXC10 MSC/VLR/SSP 1X stands for The CDMA mobile switching center/visitor location register product.
MSC is a functional entity that performs the controlling and switching of mobile subscribers within the area it serves, and it is automatic switching equipment for the traffic between MSCs or between MSC of CDMA network and switches of other public networks.
VLR is a dynamic database used by MSC for information index. It stores all related information of mobile subscribers that enter its coverage area, which enables MSC to set up incoming and outgoing calls.
Subscriber parameters include: subscriber number, location area identity(LAI), user’s status, services which subscriber can use and so on.
When the subscriber leaves this area, it should register in another VLR, and the previous VLR will delete all the data about this subscriber.
VLR can be built together with the MSC or set separately
• Conception: It is an entity to prevent illegal subscribers from accessing CDMA network. It can generate the parameter to confirm the subscriber’s identity. At the same time it can encrypt user’s data according to user’s request.
Database: save MIN,ESN, authentication key)
Generator of random number
AUC can be built separately or together with HLR
Architecture of CDMA system
Operation and Maintenance Center (OMC) OMC provides operation and maintenance services to the network operator, manages the registered subscriber information and conducts network planning to enhance the overall working efficiency and service quality of the system. Based on the main maintenance functions, there are two types of operation and maintenance centers: OMC-S and OMC-R . The OMC-S is mainly responsible for maintenance of MSS while the OMC-R is mainly for BSS. We also call OMC as background . Architecture of CDMA system
RAKE receiving, diversity sending, and smart antenna
Softer handoff between sectors, soft handoff, and hard handoff
Cell breathing, blossoming, wilting, and TPTL
High efficient wireless resource management
Hot standby for key components
Automatic and periodical performance test to ensure reliability
All boards can be hot swapped, supporting on line maintenance
Module function is relatively independent. Single rack of BTS can accomplish 1,2,3 and 4 carriers, supporting Omni-, 2-sector, 3-sector and 6-sector cell. Supporting capacity expansion in stacking method
Message Type (MSG_TYPE) – Identifies this message and determines its structure (set to the fixed value of ‘00000001’)
Protocol Revision Level (P_REV) – Shall be set to ‘00000001’
Minimum Protocol Revision Level (MIN_P_REV ) – 8-bit unsigned integer identifying the minimum protocol revision level required to operate on the system. Only mobile stations that support revision numbers greater than or equal to this field can access the system.
System ID (SID) – 16-bit unsigned integer identifying the system
Network ID (NID) – 16-bit unsigned integer identifying the network within the system (defined by the owner of the SID)
Pilot PN Sequence Offset Index (PILOT_PN ) – Set to the pilot PN offset for the base station (in units of 64 chips), assigned by the network planner
Long Code State (LC_STATE) – Provides the mobile station with the base station long code state at the time given by the SYS_TIME field, generated dynamically
System Time (SYS_TIME) – GPS system-wide time as 320 ms after the end of the last superframe containing any part of this message, minus the pilot PN offset, in units of 80 ms, generated dynamically
Each Access Channel is associated with only one Paging Channel
Up to 32 access channels (0-31) are supported per Paging Channel
CDMA MS Call Processing Power-Up Initialization Idle System Access Traffic Mobile station has fully acquired system timing Mobile station receives a Paging Channel message requiring ACK or response, originates a call, or performs registration Mobile station is directed to a Traffic Channel Mobile station ends use of the Traffic Channel Mobile station receives an ACK to an Access Channel transmission other than an Origination Message or a Page Response Message Mobile station is in idle handoff with NGHBR_CONFG equal to ‘011’ or is unable to receive Paging Channel Message
ZTE Instruments reading the Primary Channel 42 and 83 in the same instrument; example felt at Namakkal and Attur.
Cell Demarcation: Subscriber of one SDCA has to work in the BTS located in the other SDCA with the dominated signal. Example at Kandhampayam and Puduchathiram. This has been experimented at Madurai MSC and to be tried at Pondichery MSC also.