Handover Mechanism in IEEE
802.16e, WiBro
by
Bhupendra Borse
WiBro Network Architecture
WiBro Specifications:
• Operating Frequency 2.4 GHz
• 9 MHz Bandwidth
• Mobility up to 60 km/hr (31 miles/hr)
Physical Layer
• R=N*b*c/T
Where:
N = Number of used sub carriers
b = Number of bits per modulation
symbol
c = Coding rate
T = OFDM symbol duration
Calculation at Physical Layer
•
Fs = floor (Sampling-factor * Channel-Bandwidth / 8000) * 8000
Where:
Sampling-Factor = Sampling Factor. This is set to 8/7 in the implementation.
Channel-Bandwidth = Channel bandwidth, in Hz
• symbol time, Tb, is calculated by using the following formula:
Tb = FFT-size / Fs
Where:
FFT-size = FFT size
• Cyclic prefix time, Tg = G * Tb
Where:
G = Ratio of cyclic prefix time to useful symbol time. The following values are
supported in the implementation: 1/32, 1/16, 1/8, and 1/4.
Tb = Useful symbol time
• OFDMA symbol time, T, is calculated by using the following formula:
T = Tb + Tg
Where:
Tb = Useful symbol time
Tg = Cycle prefix time
Types of Handover
• BS initiated HO
• MS initiated HO
BS  Base Station
MS Mobile Station
BS initiated HO
MS initiated HO
Scenario 1: Two Cell Two HO
Handover shown
Analysis : MAC Layer
Analysis : Application Layer
VBR Client
VBR Server
Scenario : Two HO using VBR
application
Analysis: Application Layer
VBR clients
VBR server
Future Work
• Handovers taking place with background
Traffic and Faults
• Handovers taking while running VoiP
application
• If Possible, Handovers under weather
effect
References
•
•
•
•
•
F. Wang et al, “IEEE 802.16e System Performance: Analysis and
Simulations”, Presented at PIMRC Conference, 2005.
R. Koodli, ”Fast Handover for Mobile IPv6,” Internet Draft,” MobileIP
Working Group, 2004
K. El Malki, ”Low Latency Handoffs in Mobile IPv4,”, Internet Draft,”
Network Working Group, 2004
IEEE P802.16e/D4, ”Draft IEEE Standard for Local and Metropolitan Area
Networks—Part 16: Air Interface for Fixed and Mobile Broadband
Wireless Access Systems,” Aug, 2004
“Design and Implementation of a Simulator Based on a Cross-Layer
Protocol between
MAC and PHY Layers in a WiBro
Compatible IEEE 802.16e OFDMA System",Taesoo Kwon, Howon Lee,
Sik Choi, Juyeop Kim, and Dong-Ho Cho,Korea Advanced Institute of
Science and Technology Sunghyun Cho, Sangboh Yun, Won-Hyoung Park,
and Kiho Kim, Samsung Advanced Institute of Technology. 01636804/05/@© 2005 IEEE Communications Magazine • December 2005