Wireless Transmission Protocols
There are several transmission protocols in wireless manner to achieve different application oriented tasks
Application of WTP:
Some of these applications are given.
Wireless Local Loop (WLL) and LMDS:
- Microwave wireless links can be used to create a wireless local loop.
- The local loop that resides between the central office (CO) and the individual homes and business in close proximity to the CO.
- An advantage of WLL technology is that once the wireless equipment is paid for, there are no additional costs for transport between the CO and the customer premises equipment.
- Local Multipoint Distribution Service (LMDS), which provides broadband telecommunication access in the local exchange.
- It Facilitates ad-hoc data transmission over short distances from fixed and mobile devices as shown in Figure.
- It uses a radio technology called frequency hopping spread spectrum. It chops up the data being sent and transmits chunks of it on up to 79 different frequencies.
- In its basic mode, the modulation is Gaussian frequency shift keying (GFSK).
- It can achieve a gross data rate of 1 Mb/s
- Primarily designed for low power consumption, with a short range (power class- dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device
Wireless Local Area Networks (W-LAN)
- IEEE 802.11 WLAN uses ISM band (5.275-5.825GHz)
- Uses 11Mcps DS-SS spreading and 2Mbps user data rates (will fall back to
- 1Mbps in noisy conditions)
- IEEE 802.11a standard provides up to 54Mbps throughput in the 5GHz band.
- The DS-SS IEEE 802.11b has been called Wi-Fi. Wi-Fi networks have limitedrange. A typical Wi-Fi home router using 802.11b or 802.11g with a stockantenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors.
- Range also varies with frequency band.
- IEEE 802.11g uses Complementary Code Keying Orthogonal Frequency Division Multiplexing (CCK-OFDM) standards in both 2.4GHz and 5GHz bands.
- Zigbee is the specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4-2006 standard for wireless personal area networks (WPANs), such as wireless headphones connecting with cell phones via short-range radio.
- Zigbee operates in the industrial, scientific and medical (ISM) radio bands 868 MHz in Europe, 915 MHz in countries such as USA and Australia, and2.4 GHz in most worldwide.
- This technology is intended to be simpler and cheaper.
- Zigbee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.