Lecture 2:. Overview of Modern Wireless Communication Systems. Last lecture we looked at an introduction to the course. History FCC and spectrum allocations. Types of wireless applications. Cellular concept Paging systems Control channels and voice channels. Call setup procedures
Overview of Modern Wireless Communication Systems
1. WLANs and Bluetooth
2. Cellular Carriers
So 24*64kbps = 1.536 Mbps, which means 24 users can be supported (with a little bit of bandwidth used for the framing bit).
As seen in figure above, each user takes a turn each 125 microseconds to send a burst of 8 bits.
Advantages uses this.
Resistant to narrowband interference - can only reasonably try to affect part of the signal.
Allows multiple users with different codes to share same range of frequencies.
The system can operate effectively at lower Signal-to-Noise ratios, so more users can be supported than for a non-CDMA system.
1) Direct Sequence (DS)
2) Frequency Hopping (FH)
2. sequenceInterim Standard 136 (IS-136)
3. sequencePacific Digital Cellular (PDC)
4. Interim Standard 95 (IS-95)
1. High Speed Circuit Switched Data (HSCSD) for GSM
1. Wideband-CDMA (W-CDMA) or the Universal Mobile Telecommunications System (UMTS)
2. cdma2000 Telecommunications System (UMTS)