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3G / UMTS Hot Spots: TDD / WLAN
Mobile phone and WLAN networks are complementary.
To provide additional capacity / technology
Required high speed transmission planning
USIM usage, identification, billing
TDD
Less mature that WLAN
System cost, user terminals?
Licensed TDD bands capacity planning easier
Several TDD base stations on the market
Market and technology needs to mature
TDD hotspot will be a part of the mobile network hotspot business case
WLAN
More mature that TDD, quick, easy, cheap to install
Unlicensed bands will get congested in public places (CeBIT effect)
Unlicensed means unregulated which means regularly a new WLAN appears and starts to interfere with your system and there very little you can do
Potentially very high speed, but more limited coverage, capacity
Backhaul transmission speed, not the air interface, possibly the limiting factor. If your transmission to WLAN location is E1, you only get 2Mbit/s
WLAN cards available, handsets coming
Infrastructure relatively cheap, but transmission cost still high
Security issues
Low entry barries to the market
Laptops come WLAN ready
WLAN networks need solid business case
Typically a corporate LAN, DSL or cable modem connection
Have first appeared: airport lounge, hotel lobby, coffee shop and uni campus for laptop access.
About three networks at 2.5GHz can function at the same location
Upgrade to 5 GHz spectrum gives smaller coverage area
VoIP applications; QoS issues; WLAN is not a substitute for 3G voice
General
User Terminal / PC card cost and usability important.
Handover and roaming issues
People come to WLAN locations - Mobile networks come to people locations
About TDD
About Wireless LANs
The specifications ot the IEEE wireless LAN family:
802.11 : Wireless LANs, provides 1 or 2 Mbps transmission in the 2.4 GHz band.
802.11a : An extension to 802.11 wireless LANs, up to 54 Mbps in the 5 GHz band.
802.11b : An extension to 802.11 wireless LANs, up to 11 Mbps (or 5.5, 2 and 1 Mbps) in the 2.4 GHz band.
802.11g : Wireless LANs which will extend the data rate of the 802.11b to 54 Mbps in the 2.4 GHz band.
802.15.1 : Wireless Personal Area Network standard based on the Bluetooth specification in the 2.4 GHz band.
802.16 : Standard for Wireless Metropolitan Area Network.
USA |
2.4000 - 2.4835 GHz |
Europe |
2.4000 - 2.4835 GHz |
Japan |
2.471 - 2.497 GHz |
France |
2.4465 - 2.4835 GHz |
Spain |
2.445 - 2.475 GHz |
Global Spectrum Allocation at 2.4 GHz [More]
WiFi and Bluetooth both occupy a section of the 2.4 GHz Industrial, Scientific and Medical (ISM) band that is about 83 MHz-wide. Bluetooth uses Frequency Hopping Spread Spectrum (FHSS) and is allowed to hop between 79 different 1 MHz wide channels in this band. WiFi uses Direct Sequence Spread Spectrum (DSSS) instead of FHSS. Its carrier does not hop or change frequency and remains centered on one channel that is 22 MHz wide. While there is room for 11 overlapping channels in this 83 MHz wide band, there is only room for three non-overlapping channels. Thus there can be no more than three different WiFi networks operating in close proximity to one another.
More on Wireless LANs: IEEE 802.11, Wi-Fi Alliance, WLANA, HiperLAN and
HiperLAN2
Wi-Fi = Wireless Fidelity generically used referring to any 802.11 network.
WLAN = Acronym for IEEE 802.11 standard Wireless Local-Area Network.
Based on Petri Possi's Hot Spot presentation
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