How Many CODES in CDMA?

There Are Three Codes in CDMA PN Long Code,PN Short Code & Walsh Code. PN Long Code The Long Code is a PN sequence that is 242 – 1 bits…

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…

CDMA Protocol Stacks

The original release of the EIA/TIA-95-B standard defined the protocol messages and formats to be used in the CDMA system. This release is know as Revision 0 of the IS-95…

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…

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…

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…

CDMA System Time

For both mobiles and base station in direct sequence CDMA must be synchronized. In the IS-95A system, synchronization is based on the Global Positioning Satellite system time. The CDMA system…

How Forward Link Channel Format in CDMA

The Base Station transmitter signal is, however, the composite of many channels (with a minimum of four). The Pilot channel is unmodulated (Walsh code 0); it consists of only the…

Forward Traffic Channel of CDMA

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…

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…

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