Forward Traffic Channel is used to Transmit Data and Signaling Information. Symbol repetition makes symbol streams at different rates adapted to those at the rate of 19.2k. The original symbol stream at the rate of 19.2Kbps will not be repeated, 9.6Kbps symbol stream will be repeated once, 4.8Kbps symbol stream will be repeated twice…. Then, … Read more
Diversity technology means that after receiving two or more input signals with mutually uncorrelated fading at the same time, the system demodulates these signals and adds them up. Thus, the system can receive more useful signals and overcome fading. A mobile communication channel is a multi-path fading channel and any transmitted signal reaches a receive … Read more
Reverse power control Open loop power control Closed loop power control Inner loop power control: 800 Hz Outer loop power control Forward power control Message transmission mode: threshold transmission periodic transmission Closed loop power control Reverse open loop power control means that based on the detected signals from a base station, a mobile station … Read more
The long code is a PN sequence with period of 242-1chips The functions of a long code: Scramble the forward CDMA channel Control the insertion of power control bit Spread the information on the reverse CDMA channel to identify the mobile stations In a reverse direction, different long codes are used for the information … Read more
It can be seen from the figure that the data are read row by row into an interleaver at the transmit end,read column by column out (this process is called interleaving) and propagated after other modulation process. Then, the data enter the interleaver at the receive end row by row and are read out column … Read more
In 2G GSM Technology in forward direction Downlink (GSM BTS to GSM Mobile). There are mainly five Downlink Logical Channel in GSM. Frequency correction channel (FCCH) Synchronous channel (SCH) Broadcast control channel (BCCH) Paging channel (PCH) Access granted channel (AGCH) Frequency correction channel (FCCH) First start with FCCH which full form is frequency correction channel … Read more
Block coding is used to detect if there are any uncorrected errors left after error correction. The cyclic redundancy check (CRC) is a common method of block coding. Adding the CRC bits is done before the channel encoding and they are checked after the channel decoding. During the transmission, there are many interferences and fading. … Read more
Multi-path combination in the BSC during soft handoffMulti-path combination in the BTS during softer handoffs Soft handoff means that during the handoff of a mobile station at the coverage edge areas of two or multiple base stations, the mobile station receives the signals from multiple base stations (two in most cases) at the same … Read more
Two points are important here: Maximum number of shift register (N) Mask The period of out put sequence is 2N-1 bits Only sequence offset is change when the mask is changed PN stands for Pseudorandom Noise sequence In CDMA system, user information is encrypted by means of scrambling. The scramble code used here is … Read more
How WCDMA Interleaving ? Effect Interleaving is used to reduce the probability of consecutive bits error Longer interleaving periods have better data protection with more delay Channel coding works well against random errors, but it is quite vulnerable to bursts of errors, which are typical in mobile radio systems. The especially fast moving UE in … Read more