MOBILE TRANSITION INTO DIFFERENT STATES

  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…

Propagation Path

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…

Propagation of Electromagnetic Wave

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…

Radio Wave Spectrum

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…

PN Code Generation & Masking

  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…

How Walsh Code Generate in CDMA

• Definition: Orthogonal functions have zero correlation.  Two binary sequences are orthogonal if the process of “XORing” them results in an equal number of 1’s and 0’s. Example:   0000…

Spread Spectrum Concept

Dsss – Direct sequence spread spectrum DSSS – Direct Sequence Spread Spectrum is a spread spectrum technology in which original data is expand using PN code randomly to reduce noise…

EVDO reverse Link

Here I write about EVDO (HSD) reverse channel in short or summarize defination. The EVDO channels for the reverse connection have a similar structure as for CDMA2000. The reverse link…

Forward link EVDO channels in Detail

A number of channels are transmitted in the forward direction to enable signalling, data and other capabilities to be handled. These channels include the Traffic channel, MAC channel, Control channel…

EV-DO forward link in short

The forward link possesses many features that are specific to EV-DO, having been optimised for data transmission, particularly in the downlink direction. Average continuous rates of 600 kbps per sector…

What is Polarization Mode for antenna

The polarization is a radiation feature for indicating the vector special direction of field strength of electromagnetic wave. If unspecified, the spatial direction of electric field vector usually serves as…