Wcdma works on wcdma cellphones as well as laptops and portable devices with wcdma modems. Four different air interface signals are considered. Difference between lte and cdma difference between. The umts physical layer utilises direct sequence spread spectrum format to enable a multiple access scheme called code division multiple access, cdma to be used. In a cdma system the same signal can be transmitted over the air interface, on the same frequency, from several base stations separated by considerable distances. In cellular telephone communications, the air interface is the radiofrequency portion of the circuit between the cellular phone set or wireless modem usually portable or mobile and the active base station. The mccdma air interface allows highcapacity networks and robustness in the case of frequencyselective channels, taking bene. In a sho all the participating base stations use the same frequency, and the result is a macro diversity situation. Gsm and dect signals, both of which use gmsk modulation and a tdma scheme.
Pdf design and implementation of mccdma systems for. The lte system can be seen as an expansion of service beyond voice calls towards a multiservice air interface. Cdma, short for code division multiple access, is inherently associated with spread spectrum communication techniques. As a subscriber moves from one cell to another in the system, the active base station changes periodically. A1 interface carries call control signaling between msc and bsc. In sdai, modules and related parameters are adapted in real time to flexibly fit all sorts of. The air interface is the wireless counterpart of the physical layer 1 in the osi model see osi model. Cdma network interfaces um interface air interface. One of the chief elements of the umts physical layer or radio interface is the signal format that has been adopted. The first air interface in the early 1900s, this marconi sparkgap transmitter top and receiver bottom comprised the first wireless telegraphy.
Air interface identification for software radio systems. Hlr,vlr,auc,eir all the registers supporting msc are explained with there features in hindi duration. Florida institute for cybersecurity fics research cis 6930 cellular and mobile network security. A possible generic downlink transmission scheme is depicted in figure 2. Also called a radio interface, the air interface defines the frequency, channel bandwidth. Wideband cdma a 3g cellular technology that uses the cdma air interface. A cdma system is based around direct sequence spread spectrum techniques.