Lg Electronics LGC800W User Manual

corresponding mobile station every 1.25 msec (800 times per second).

By doing so, the gain tolerance and the different radio propagation loss on the forward/backward link are

complemented.

The bi-directional voice service having variable data speed provides voice communication which employs voice

encoder algorithm having power variable data rate between the mobile telephone cell site and mobile station. On

the other hand, the transmit voice encoder performs voice sampling and then, creates encoded voice packets to be

sent out to the receive voice encoder, whereas the receive voice encoder demodulates the received voice packets

into voice samples.

One of the two voice encoders described in the above is selected for use depending on inputted automatic

conditions and message/data; both of them utilize four-stage frames of 9600, 4800, 2400, and 1200 bits per

second. In addition, this type of variable voice encoder utilizes adaptive threshold values when selecting required

data rate. It is adjusted in accordance with the size of background noise and the data rate is increased to high rate

only when the voice of caller is inputted.

Therefore, background noise is suppressed and high-quality voice transmission is possible under the environment

experiencing serious noise. In addition, in case the caller does not talk, data transmission rate is reduced so that

the transmission is carried out in low energy. This will reduce the interference on other CDMA signals and as a

result, improve system performance (capacity, increased by about two times).

CDMA signals have the function of effectively protecting call confidentiality by spreading and interleaving call

information in broad bandwidth. This makes the unauthorized use of crosstalk, search receiver, and radio very

hard substantially. Also included is the encryption function on various authentication and calls specified in IS-95

for the double protection of call confidentiality.

During the soft hand, the cell site already in the busy state and the cell site to be engaged in the call later

participate in the call conversion. The call conversion is carried out through the original call connection cell site,

both cell sites, and then, new cell site. This method can minimize call disconnection and prevent the user from

detecting the hand-off.

Unlike the existing analog cellular system, the CDMA system can reuse the same frequency at the adjacent cell