Macro Diversity Handover in Multi-carrier System
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-08/1008
Date Submitted:
2008-09-05
Source:
Yih-Guang Jan, Yang-Han Lee,
Ming-Hsueh Chuang, Hsien-Wei Tseng,
Wei-Chieh Tseng, Po-Jung Lin, Ting-Chien Wang
Tamkang University (TKU)
Shiann-Tsong Sheu
National Central University (NCU)
Whai-En Chen
National Ilan University (NIU)
E-mail: yihjan@yahoo.com
E-mail: stsheu@ce.ncu.edu.tw
E-mail: wechen@niu.edu.tw
Venue:
PHY: Multi-Carrier Operation; in response to the TGm Call for Contributions and Comments 802.16m-08/033 for Session 57
Base Contribution:
N/A
Purpose:
Propose a Macro Diversity Handover in Multi-carrier System
Notice:
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contained herein.
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Introduction (1/3)
• With the development of new technologies, mobile communication
services have been actively developed into the wireless network and
also has moved into the study and development of high speed
mobile station services.
• IEEE 802.16m is the standard of next generation wireless
communication system, it has the advantages of wide bandwidth,
high transmission speed and wide coverage areas etc.
• Although it has many advantages in wireless communications, it has
accompanied with it various kind of interferences, including the
interferences between mobile to mobile, mobile to base station and
base station to base station.
Introduction (2/3)
• When mobile moves the distance between the mobile station and
the base station changes; when the communication distance
changes the communication channel also suffers various
interferences, the mobile station received signal strength will
consequently be varied. As the mobile station moves further away
from the base station its received signal strength will be becoming
weaker it needs to resort to handover (HO) process to maintain a
good quality of service and to maintain the data can be transmitted
normally.
• Consequently in the consideration of the overall wireless
communication system the handover process plays the vital role in
the wireless communication.
Introduction(3/3)
• In this contribution we will be based on the standard of 802.16m
system to propose the multi-carrier handover process so that this
handover mechanism can be selected and implemented into the
802.16m system.
• In the discussion of multi-carrier handover mechanism we assume in
our discussion that the system synchronization has completed
therefore the synchronization process will not be discussed in this
contribution.
• We will be in this contribution to utilize the concept of multi-carrier
handover to design the macro diversity soft handover technique.
Macro Diversity Handover (1/4)
• The main task of soft handover is to the improve the drawbacks of
hard handover and to improve the service quality and to reduce the
drop rate.
• The concept of soft handover is before the MS terminates its
connection with the serving BS it needs to manke connection with
other BS, in other words in the handover process the MS has
connection with more than one BS.
• In the OFDMS system it can be classified into two categories in the
soft handover, namely Macro Diversity Handover (MDHO) and Fast
Base Station Switching (FBSS).
• In considering the technique for multi-carrier HO it is suitable to use
the design technique of soft handover process.
Macro Diversity Handover (2/4)
• Either with MDHD or FSBB handover, it will be in the MS to maintain
a list of base stations, namely the Diversity Set. In the Diversity Set
it will define one BS as an Anchor BS, it has the same function as
the serving BS; its main function is to proceed and maintain the
information exchange with the MS.
• By taking MDHO for example, the receiving signal strength of the
MS from the outer layer neighboring BS is not strong enough and
will not be included in the Diversity Set and consequently the outer
layer BSs are not included in the Diversity Set. The MS will
communicate with all active BSs in the Diversity Set, in other words,
the MS will be simultaneously to transmit or receive data with many
BSs.
Macro Diversity Handover (3/4)
• When MS moves, the Active BS list in the Diversity Set is constantly
modified through the Anchor BS; when the signal strength of the
Active BS becomes weak it will be removed from the list through the
Anchor BS, on the contrary when a BS has stronger signal strength
it will be included in the Diversity Set through the Anchor BS.
• The design of soft handover process is suitably implemented with
multi-carrier HO technique. The multi-carrier HO can be expanded to
three, four or many carriers technique. One of the carrier is used to
contact with the Anchor BS while the other carrier is used to contact
with the Active BS to complete the soft handover implementation.
• In the following figure it discusses and models the multi-carrier
MDHO process.
Macro Diversity Handover (4/4)
Diversity Set
Active BS
Neighbor BS
Anchor BS
Active BS
Neighbor BS
Area of Neighbor BS
UL and DL communcation
Include Traffic
Neighbor BS
Only signal level measurement
No Traffic
Carrier 1
Anchor
BS
Carrier 2
………………
Carrier N-1
Carrier N
Active BS ………… Active BS Active BS
MS
Conclusion
• In this contribution we use the multi-carrier handover process to
design the soft Macro Diversity Handover, it concludes with a
system flow chart as shown in the following figure. It is proposed to
be adopted in the 802.16m as its handover algorithm.
Text Proposal
===================Start of Proposed Text====================
19 Support for Multi-carrier
19.x Multi-carrier Handover Method
19.x.1 Macro Diversity Handover
The macro diversity handover mechanism with three carriers involved in the handover
has the flow chart as shown in the following figure:
Carrier 2
Carrier 3
Search Active
BS
START
Login to Anchor
BS
Search Active
BS
Login to Active
BS
Power Measurement
Login to Active
BS
Power Measurement
Power Measurement
Active BS
else
Power of carrier 3
Anchor BS Active BS
< 0 dB
Power - Power
Active BS <-105 dBm
else
Active BS <-105 dBm
Yes
else
Yes
Active BS
Power of carrier 2
Active
BS
Anchor
BS
Received signal level
Carrier 1
Hysteresis
T1
Handover Confirm
Get T1
Handover Confirm
Get T1
Determine which Active BS
Determine which Active BS
Power Measurement
Anchor BS Active BS
Power
Power
Power Measurement
else
Anchor BS Active BS
Power
Power
>=Hysteresis
Yes
Get T2
Get T2
No
T2 – T1 < x
sec
Power Measurement
Trigger
HO success
Login to new Anchor BS
No
Power Measurement
Yes
Logout to old
Anchor BS
else
>=Hysteresis
Yes
T2 – T1 < x
sec
T2
Yes
Anchor BS<-105 dBm
else
Anchor BS<-105 dBm
Yes
else
Yes
fail
Trigger
HO success
Login to new Anchor BS
fail
===================End of Proposed Text===================
Time