RECENT TRENDS IN WIRELESS COMMUNICATION
RECENT TRENDS.ppt (Size: 544 KB / Downloads: 192)
Where is wireless broadband today? Where has it come from in the last decade? What is its future potential?
What are key wireless communication concepts?
How do they feature in modern/emerging wireless systems (Wifi: 802.11a/b/g/n, 3G, mobile WIMAX: 802.16e)?
Modern wireless systems – WiFi , Bluetooth, Zibgee, 3G, GSM, CDMA, WiMAX, UWB,. .
Mostly radio transmission
Ad hoc networks
No problems with wiring
Robust against disasters like earthquake, fire
Low transmission rates for higher no. of users
Many national regulations, global regulations
Restricted frequency range, interferences of frequencies
Nevertheless, in the last 10-20 years, it has really been a wireless revolution…
Early Wireless Systems
1st Generation: Analog: early 80s
AMPS: FDMA with 30 KHz FM voice channels.
FCC increased the cellular spectral allocation from 40 MHz to 50 MHz.
Two 25MHz channels: DL and UL (FDD)
Analog - very susceptible to static and noise
2nd Generation: digital: early 90s
higher capacity, improved cost, higher data rates for support of digital services,
DECT: 1880-1900 MHz spectrum, multicarrier /TDMA/TDD structure
FHMA/TDMA/TDD provides up to 120 channels
Interference-free wireless operation ~100 to 500 mts outdoor
Average data transmission: 1.2 Mbps
Local area networking technology designed to provide in-building or campus broadband coverage
Based on IEEE 802.11a/b/g/n standards
Much higher peak data rates + larger bandwidth (20 MHz)
Beyond buildings: Metropolitan-wide (Muni-Fi), Neighborhood Area Networks (NaN), hotspots
Wide availability of terminal devices
Covers greater distances
Wi-Fi systems - not designed to support high-speed mobility.
High power consumption
Requires more expensive hardware
CDMA Broadband: 1xEV-DO
High-speed data standard defined as an evolution to second generation IS-95 CDMA systems
Peak downlink data rate of 2.4 Mbps in a 1.25 MHz channel.
Flexibility to support both user- and application- level QoS
User-level QoS – providers offer premium services
Application-level – operators allocate resources - applicants need
Multimode 1xEV-DO - will let subscribers receive incoming voice calls even while actively downloading data
Support high speed internet access at pedestrian or vehicle speeds
Multicast and broadcast services - supported
Wireless Technology – rapidly growing and generating tremendous changes in telecommunications and networking
Data transmission rates increased tremendously from 9.6 kbps (GSM) to 2Mbps (WCDMA), increasing more than 200 times within last 10 yearsMore ambitious 4G – approximately 1 Gbps
Great demands on capacity and quality offered over wireless communication links have pushed us hard to innovate new design methodologies and concepts for the wireless systems and networks.
But, despite many promising technologies, the reality that
… services many users at high data rates …
…. (fixed and mobile) …
… with reasonable bandwidth and power resources…
… while maintaining high coverage and quality of service
….. has not yet been achieved.