Difference between first and second generation cellular systems Digital traffic channels –first-generation systems are almost purely analog; second-generation systems are digital Encryption –all second generation systems provide encryption Error detection and correction –second-generation digital traffic allows for detection and correction, giving clear voice reception Channel access
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In a cellular system, the operator provides aservice that you can be anywhere where you
want In cordless what the operator provides is simply a wire-line
telephone link to your house. And there you have a small
personal "base station" so you can walk around yourhouse with a direct link to your own base station. Butthere is no provision for taking your cordless phone toanother city and placing a call there. ... ."
Digital: Gaussian Frequency shift keying. The cordless phones had better speech quality, were more resistant to interference, noise and fading as compared to the
earlier generation. The digital signals were also very hard to intercept and decode, and thus
provided a high level of security. The user needed to enter a PIN number in the cordless phone to gain
access to it. Thus it provided safety against misuse if the handset fell into the hands of a stranger.
Bandwidth: 864.10 MHz to 868.10 MHz. 40 channels each having a bandwidth of 100 KHz.
CAI Full duplex operation is obtained by the use of a digital
technique known as time division duplex (TDD). TDD CT2 frame consisted of 2 ms.Forward:1ms and reverse :1ms.
When an incoming call is detected by the base station, it scansthe 40 r. f. channels to find a free one that has an adequatesignal-to-noise Ratio.
The base station then transmits a call signal over the selectedchannel.
Periodically the handset moves out of its SLEEP state into itsSCAN state, in which it scans the r.f. channels.
When the call signal is detected on one of the r.f. channels, thehandset remains on that frequency and achieves bitsynchronization with the base station. The handset then
checks that the call is for it (not for someother handset) ; if so , burst synchronization is obtained toestablish a link to the base station. Theringer of the handset then rings until the call is answered,