Cdma Concepts Introduction To Cellular Communication

How many CDMA stations are there?

3. There are four stations communicating using CDMA (code division multiple access). The code assigned to each station is as follow: B: (+1 -1-1) D: (+1-1 +1-1) At the receiving end, a signal (+2 +2 +2 -2) (000 +4) (0 +4 00) (+2 -2 +2 +2) is received.

How many code channels are available in CDMA?

Although not available code channels are 64, it may not be possible to use a single time, since the CDMA frequency is the same. Flexible capability means that all the code channels can be pursued at a time, but at the expense of quality. 14. Describe the Centralized Methods in CDMA. 1.25 MHz of FDMA channel is divided into 64 code channels.

How many dB does CDMA use?

For CDMA P (gain) = 10log (1228800/9600) = 21dB Actual processing gain = P (gain) - SNR = 21 7 = 14dB CDMA uses variable rate coder The Voice Activity Factor of 0.4 is considered = -4dB. CDMA has 100% frequency reuse.

How many CDMA phones are there in the world?

(GPS is straight forward: Only 33 satellites) Say, there are N=100 million CDMA handsets worldwide. CDMA uses 128 bit Gold codes, so each BTS can support K=128 simultanuous users (and more by increasing interference). What, when and how do the N cellphones get their codes assigned?

What are CDMA codes?

The basic principle is that different CDMA codes are used to distinguish between different users. Forms generally used are direct sequence spread spectrum modulation (DS-CDMA), frequency hopping or mixed CDMA detection (JDCDMA). Here, a signal is generated which extends over a wide bandwidth.

How does CDMA recognize a signal?

For this reason, CDMA is able to recognize by decomposing each of the path to reach with the time difference. From this, it receives a different paths of signal each one separately, by summing later, it can prevent signal degradation. This is called as the RAKE receiver.