Introduction Technology Organizations Pros
and Cons FAQs Resources
- High-speed: Physical Layer bit rates up to 54Mbps, application
throughput > 20Mbps
- QoS support: Suitable for real-time applications such as video, voice,
and other multimedia
- OFDM modulation scheme is robust in highly dispersive environment,
eliminating the need of complicated equalization
- Interoperability: with Ethernet, 3G, FireWire (IEEE 1394), ATM
- Flexibility: link adaptation; dynamic frequency selection; power
control
- Security and authentication mechanism
- Higher cost (mainly due to the highly-linear amplifier for OFDM)
- Tedious protocol specification
- No commercial products in market till now (Will be available by the end of 2001, according to Ericsson)
IEEE 802.11a
and HiperLAN 2 employ the same OFDM technology, have almost the same physical
layer, and differ mainly in the MAC layer only.
Comparison
of IEEE 802.11 and HiperLAN 2
Table below summarizes the
characteristics of 802.11, 802.11b, 802.11a, and HiperLAN2. (from H2GF white
paper)
|
Characteristic |
802.11 |
802.11b |
802.11a |
HiperLAN2 |
|
Spectrum |
2.4 GHz |
2.4 GHz |
5 GHz |
5 GHz |
|
~Max physical rate |
2 Mb/s |
11 Mb/s |
54 Mb/s |
54 Mb/s |
|
~Max data rate, layer 3 |
1.2 Mb/s |
5 Mb/s |
32 Mb/s |
32 Mb/s |
|
Medium access control/Media sharing |
Carrier sense |
CSMA/CA |
|
Central resource control/ TDMA/TDD |
|
Connectivity |
Conn.-less |
Conn.-less |
Conn.-less |
Conn.-orientated |
|
Multicast |
Yes |
Yes |
Yes |
Yes |
|
QoS support |
(PCF) *2 |
(PCF) *2 |
(PCF) *2 |
ATM/802. 1p/RSVP/DiffServ (full
control) |
|
Frequency selection |
Frequency-hopping or DSSS |
DSSS |
Single Carrier |
Single carrier with Dynamic Frequency
Selection |
|
Authentication |
No |
No |
No |
NAI/IEEE address/X.509 |
|
Encryption |
40-bit RC4 |
40-bit RC4 |
40-bit RC4 |
DES, 3DES |
|
Handover support |
(NO) *3 |
(NO) *3 |
(NO) *3 |
(No) *4 |
|
Fixed network support |
Ethernet |
Ethernet |
Ethernet |
Ethernet, IP, ATM, UMTS, FireWire,
PPP *5 |
|
Management |
802.11 MIB |
802.11 MIB |
802.11 MIB |
HiperLAN2 MIB |
|
Radio link quality control |
No |
No |
No |
Link adaptation |
*1. Two different modes supported, multicast via a dedicated MAC-ID (same as for
802.11) and N*unicast for improved quality.
*2. Point Control Function, a concept defined in 802.11 to allow certain time
slots being allocated for real-time critical traffic.
*3. Requires signaling over the fixed network, which is still proprietary.
*4. Requires signaling over the fixed network, to be specified by H2GF.
*5. Ethernet
supported in first release.