Random frequency selection in femtocell
(P80216m/D2-15.4.11)
Document Number: IEEE C802.16m-09_2401
Date Submitted: 2009-11-6
Source:
Kanchei(Ken) Loa, Yi-Ting Lin, Tsung-Yu Tsai, Yung-Lan Tseng
E-mail: loa@iii.org.tw
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
• To increase the system capacity, interference
mitigation is an important technology.
• When the number of Femto ABSs is large, the
pre-scheduled mechanisms (TDM or FDM) may
not allocate the radio resource efficiently.
– FFR may not satisfy the interference mitigation
between femtocells.
• We propose interference mitigation schemes for
the femtocell by selecting the radio resource
randomly to evade the interference.
Proposed interference mitigation
scheme
• Frequency partition based
– The Femto ABS and the Macro ABS operate
in different frequency partitions.
– Furthermore, the Femto ABS selects the
resources (frequency band and subframe) to
avoid interference from the neighbor Femto
ABSs.
IM between macrocell and
femteocell
• The Femto ABS is proposed to be able to obtain
the frequency partitions of the Macro ABS from
the SFH and avoids scheduling the occupied
frequency partitions to evade interference.
IM between femtocells
• When the number of Femto ABSs is large, four
frequency partitions cannot satisfy the
interference mitigation between Femto ABSs.
• The frequency partition should be partitioned
into smaller granularities such that the small
granularities could be used by the Femto ABS.
– The smaller granularity may be LRU or subband.
– In such case, the Femto ABSs randomly select the
smaller granularities based on a random number
generator maintained in the Femto ABS and AMS.
– The random number generator is a function of cell ID,
super frame number, and reuse factor.
Proposed IM procedure
Obtain the FFR information from
the SFH of the Macro ABS
Interference mitigation
between macrocell and
femtocell
Schedule the frequency partition
not occupied by the Macro ABS
Randomly schedule the
LRU/Subband based on a random
number generator maintained in
the Femto ABS and AMS.
Interference mitigation
between femtocell and
femtocell
Proposed text
[Add the following text in the section 15.4.11 on page 551 (line 48) as
shown below]
A Femto ABS may randomly select the frequency band to avoid the
mutual interference among Femto ABSes based on a random function.
The random function is maintained in the Femto ABS and AMS and is a
function of cell ID and super frame number.