Monday, May 19, 2008

802.16e Protocol Architecture

Traffic (yellow) and Signalling (green) planes of 802.16e standard are shown above.

Saturday, May 10, 2008

Protocol Layer Structure


Service specific Convergence Sublayer (CS):
  • Transformation or mapping of external network data
  • Classify external network SDUs and associate them with proper MAC service flow (assigns SFID) and CID. SFID assignement is based on the QOS
  • Payload Header Supression ()

MAC Common Part Sublayer (MAC CPS):

  • Core MAC functionality of system access
  • Bandwidth allocation
  • Connection establishment and maintainence
  • Classified to perticular MAC conection
  • Quality of Service (QOS)
  • Scheduling of data over PHY

Privacy Sublayer:

  • Providing authentication
  • Secure key exchange
  • Encryption

Physical Layer (PHY):

  • OFDMA,
  • MIMO, AAS
  • Space Time Coding (STC), Beam Forming
  • HARQ
  • Adaptive Modulation and Coding (AMC)
  • Convolution Turbo Coding (CTC)

Thursday, May 8, 2008

What makes WiMax interesting ?

WiMax is a wireless broadband solution that offers rich set of features with lots of flexibility in term of system deployment and service offering. Some of the salient features highlighted below:

- LOS and NLOS communication
- OFDMA based physical layer
- IP based architecture
- High data rate
- Scalable bandwidth
- Adeptive modulation and coding
- Flexible and dynamic per user resource allocation
- Support for Quality of Service
- High level of security
- Mobility

Mobile WiMax and WiBro PHY Specification

Mobile WiMax PHY Specification
Frequency Band2Ghz-11Ghz for fixed & 2Ghz-6Ghz for mobile application
Channel BandwidthScalable bandwidth between 1.25Mhz to 20Mhz
FFT sizeMobile-28,512,1024,2048 and Fixed-256
DuplexingTDD and FDD
Multiple AccessSOFDMA
Modulation schemeQPSK, 16QAM, 64QAM
Frame length5mSec
Data throughput~ 70Mbps DL/UL
Mobility~ 120kmph
Cell coverage1mile-3mile

WiBro PHY Layer Specification
Frequency Band2.3Ghz-2.4Ghz
Channel BandwidthScalable bandwidth between 1.25Mhz to 20Mhz
FFT size8.75Mhz
DuplexingFDD
Multiple AccessOFDMA
Modulation schemeQPSK, 16QAM, 64QAM
Frame length5mSec
Data throughput~ 50Mbps DL/UL
Mobility~ 100kmph
Cell coverage~1km
Channel CoddingCTC(Convolution Turbo Coding)
Key FeaturesAMC, HARQ, MIMO etc..