Get Here about CDMA technology and How CDMA Works, CDMA Solution and CDMA RF Optimization.
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 to change the forward transmitting power or not. In IS-95 system, the forward power control is slow but in CDMA2000 system it is fast. Forward … 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
Formulated by the European standardization organization 3GPP, the core networkevolves on the basis of GSM/GPRS and can thus be compatible with the existingGSM/GPRS networks. It can be based on the TDM, ATM and IP technologies toevolve towards the all-IP network architecture. Based on the ATM technology, theUTRAN uniformly processes voice and packet services and evolves … Read more
All MS transmit on same frequency but with different PN codes to create different logical channels. Some channels marked for Access are used for signaling and control. While Walsh Codes identifies different channels, PN codes are used to identify Cells (by 15 bit code) and MS’s (by 42 bit codes). As each MS receives a … Read more
Functions of the cdma2000 Signaling Services Layer The Signaling Services Layer processes all messages exchanged between the mobile and the base station. These messages control such things as call setup and tear down, hand offs, feature activation, system configuration, registration and authentication. In the mobile, the Signaling Services Layer is also responsible for maintaining the … Read more
A mobile will in one of four states after it is powered on. Initialization State In the Initialization State, the mobile tunes to the first preferred RF frequency channel and attempts to decode the Pilot Channel. If a pilot is not found, the mobile tries to decode a pilot on another RF channel or … Read more
Radio wave can be propagated from the transmitting antenna to the receiving antenna in many ways: perpendicular incidence wave or ground refraction wave, diffraction wave, troposphere reflection wave, ionosphere reflection wave, as shown in the diagram. As for radio wave, the most simple propagation mode between the transmitter and the receiver is free space propagation. … Read more
When the radio wave propagates in the air, the electric field direction changes regularly. If the electric field direction of radio wave is vertical to the ground, the radio wave is vertical polarization wave If the electric field direction of radio wave is parallel with the ground, the radiowave is horizontal polarization wave Propagation of … Read more
The radio waves are distributed in 3Hz ~ 3000GHz. This spectrum is divided into 12 bands, as shown in the above table. The frequencies in each specific band present unique propagation features: The lower the frequency is, the lower the propagation loss will be, the farther the coverage distance will be, and the stronger the … Read more
PN Code Generation PN Code Generation PN codes are generated from prime polynomials using modulo 2 arithmetic. The state machines generating these codes are very simple and consist of shift registers and XOR gates . Masking will cause the generator to produce the same sequence, but offset in time PN Offset (Masking) Masking … Read more