Transcript IEEE C802.16m-09/2400

Measurement based interference mitigation schemes for femtocell
(P80216m/D2-15.4.11)
Document Number: IEEE C802.16m-09_2400
Date Submitted: 2009-11-6
Source:
Kanchei(Ken) Loa, Yi-Ting Lin, Chun-Yen Hsu, Tsung-Yu Tsai, Chiu-Wen Chen, Youn-Tai Lee
E-mail: [email protected]
Institute for Information Industry (III)
Venue:
Base Contribution: N/A
Re : P802.16m/D2
Purpose: Discussion and approval of the proposal into the IEEE P802.16m/D2
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Introduction (1/2)
• When the Femto ABS reuses the radio resource of the
Macro ABS, the key interference mitigation is to prevent
the Femto ABS from utilizing resource units occupied by
the Macro ABS.
• This contribution proposes two approaches for
interference mitigation based on measuring the
frequency partition (FP) or resource units of the Macro
ABS.
– Femto ABS identifies the occupied FP/PRUs by measuring the
received interference power in DL. After identifying the occupied
FP/PRUs, the Femto ABS avoids to schedule these occupied
FP/PRUs to evade interference.
Introduction (2/2)
• Approach 1
– Femto ABS performs the interference mitigation autonomously.
– When the Femto ABS can not access the scheduling information
from the air interface or wired interface.
• Approach 2
– A hybrid approach to support the identification of the occupied
PRUs, by which the Femto ABSs identify the occupied FP/PRUs
by combining the channel measurement results with the
FP/PRUs scheduling information provided by the Macro ABS.
Channel measurement based interference
mitigation scheme
• The operation of this scheme is proposed as follows.
– The Femto ABS periodically measures the received interference
power in DL on each FP/PRU.
• The Femto ABS could perform measurement in low dusty mode.
• The duration of measurement (i.e. unavailable interval) depends on
the traffic pattern.
– The Femto ABS considers that a FP/PRU is occupied by the
macrocell if this quantity exceeds a certain value.
– In the duration not performing measurement, the Femto ABS
only schedules FPs/PRUs not considered as occupied by the
Macro ABS.
– By channel measurement, the Femto ABS also obtains following
information from the Macro ABS
• The traffic load of the Macro ABS,
• Normalized correlated PRU allocation in the macrocell, and
• PRU allocation dependence.
Definitions of measurement parameters
• Traffic load φ
– Traffic load φ indicates the percentage of PRUs occupied by the
Macro ABS in one measurement duration. Therefore, the number
of PRUs occupied by the Macro ABS in one measurement
duration is φ×NPRU where NPRU is the number of PRU in one
measurement duration.
• Normalized correlated PRU allocation in the Macro ABS η
(normalized to NPRU)
– η indicates the percentage of PRUs in φ whose allocation in
current measurement duration has probability ρ the same as the
PRU allocation in previous measurement duration.
• PRU allocation dependence ρ
– ρ is the percentage that the PRU allocation in this measurement
duration is the same as the previous one.
The hybrid approach
• The Femto ABS combines its channel measurement
results and the FP/PRUs scheduling information
provided by the Macro ABS.
• The detail of this hybrid approach is as following:
– If the maximum delay of the wired interface is acceptable, the
Femto ABS sets its measurement period to this maximum delay
value.
– The Femto ABS may requires the Macro ABS to provide its
FP/PRUs allocation information periodically.
– The Femto ABS interlaces its channel measurement and the
periodical report of the FP/PRUs usage provided by the Macro
ABS.
– The Femto ABS only schedules FP/PRUs not considered as
occupied by the Macro ABS.
The hybrid approach
The measure period, which is
set to the value of the maximum
delay of the wired interface
The measure duration where
the Femto ABS performs the
channel measurement.
The Femto ABS can transmit
data in this duration.
...
The maximum
delay of the wired interface
Macro ABS provides the
partial FP/PRUs usage in this
duration. The Femto ABS can
perform data transmission in
this duration.
How the Macro ABS provide the Femto
ABS scheduling information
• Through wired interface
– The delay of the wired interface has large variance,
and the scheduling information may be out-of-date.
• Through air interface
– The Femto ABS obtain the frequency partition from
the Macro ABS’s SFH, and the Femto ABS avoids to
schedule the FP to evade interference.
– The ability of providing other scheduling information,
such as carrier frequency, LRU, or subband needs
further study.
– The Femto ABS is proposed to be able to
communicate with the Macro ABS by air interface.
Proposed text
[Modify the section 15.4.11 on page 551 (line 40-47) as shown below]
A Femto ABS may select the carrier frequency, frequency partition, or
LRUs to avoid the mutual interference between macro/micro and Femto
ABSes or among Femto ABSes based on the measurement result of
surrounding reception power.
Femto ABS can measure the signal strength for the carrier frequency,
frequency partition, or LRUs of the neighbor macro/micro/femto cells. In
addition, the Femto ABS can receive A-Preamble from the neighbor
macro/micro/femto cells and obtain information on cell type. The Femto
ABS may select the carrier frequency, frequency partition, or LRUs based
on the measurement result on signal strength and the information on cell
type.