Tag Archives: code

Basic Work of WCDMA Physical Channel

A physical channel is defined by a specific carrier frequency, code (scrambling code, spreading code) and relative phase. In UMTS system, the different code (scrambling code or spreading code) can distinguish the

Types of Power Control in CDMA

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

Long Code & Short Code In CDMA

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

Interleaving in CDMA

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

WCDMA Radio Interface Channel Definition

Logical Channel = information container  Defined by is transferred. Transport Channel = characteristics of transmission Described by and with data is transmitted over the radio interface . Physical Channel =

WCDMA Source Coding

AMR (Adaptive Multi-Rate) Speech A integrated speech codec with 8 source rates The AMR bit rates can be controlled by the RAN depending on the system load and quality of

Soft/Softer Handoff in CDMA

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

Forward Power Control in CDMA

Message Transmission Mode MS measures the frame quality and informs the base station to the result i.e. whether it is in the threshold or periodical  mode. Base station determines whether 

Scrambling (M) sequence in CDMA

  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

How Modulation-QPSK in CDMA ?

     In an actual application, the system implements the modulation in this way:  as shown above, I and Q channel sequences in the figure represent two channels of cyclic PN