Resource Allocation Policy to Avoid
Interference between Cellular and D2D
Links/ and D2D Links in Mobile Networks
報告人：王姿穎
學號：MA4G0202
Outline
1. Introduction
2. System model
3. How to assign D2D link resource
4. Numerical example
5. Concluding
1.Introduction
The goal of this paper is to show how to cope with
interferences between D2D and cellular cell and
between D2D links. The considered service is limited
by D2D commercial advertisement broadcasted by
shops in a small area.
2. System model
System Model with Frequency Reuse Factor 3
2. System model
Frequency Reuse(頻率重複使用)
在整個系統涵蓋範圍內，讓許多基地台使用相同的無線電
頻率同時進行通訊，以増加系統的通訊容量。前提是兩cell
得相距夠遠， 且信號強度不相互干擾。
群組
(cluster)






cell
2. System model
可使用頻率
全部頻寬
地區
Allocated Frequency Bandwidth in Each Area
2. System model
Interference Model
3. How to assign D2D link resource
Step 1 : Interference cancellation between cellular link and D2D link
To solve the problem, an additional frequency fraction which
considers D2D links as an adjacent cell should be assigned.
On one hand interferences from cell edge are effectively
eliminated. On the other hand the interferences from users
located at cell core still remain un-removed, which can be
eliminated with D2D belt.
3. How to assign D2D link resource
Step 1 : Interference cancellation between cellular link and D2D link
The white area, a frequency band
used by D2D link, the center of the
cell, but is unavailable for users
located at edge of cell center area.
Such a frequency assignment can
D2D Belt
get rid of the cellular link-driven
interferences on D2D link.
Proposition 1: Even at the center of the cell, if within D2D belt, the frequency band is not available.
3. How to assign D2D link resource
Step2 : Interferences cancellation between D2D links
The new assignment method owes its key concept to the
system information. System information is literally a piece of
information for a terminal to attach a base station. Pieces of
information are categorized by its nature into a number of
system information messages and transmitted from base
stations to terminals. From the messages terminals gain the
required information to attach base stations. To that end,
system information messages are scheduled open only to
different sub-frames. By doing so, sub-frames used by D2D
links are allocated in a different way.
3. How to assign D2D link resource
Step2 : Interferences cancellation between D2D links
Basic Assumptions：
 The AD service through each D2D link is provided for
specific amount of time, which is the same for all cells
(D2D AD window : w).
 The AD service through each D2D link is transmitted
continuously at a certain interval of T whose definition
is a multiple of more than 20ms radio frames (one
radio frame = 10 subframes, one subframe = 1ms.)
Proposition 2: In order to eliminate interferences between D2D links, different
subframes are allocated to each D2D link.
4. Numerical example
SUBFRAME ALLOCATION EXAMPLES (R=3, W=2)
1)
2)
3)
4)
5)
R = frequency reuse factor
i = AD D2D link of cell
n=i mod R
x=n*w (D2D AD window : w)
from the subframe a, the service is provided for the time of w and
satisfies a=x mod 10
6) first service is given, continuously at the interval of T,to RF that
satisfies RF mod T = FLOOR(x/10)
4. Numerical example
The link gain between mobile 𝑖 and store 𝑘, 𝑔𝑖𝑘 is given by
. 𝑠𝑖 is shadow fading factor between mobile i and store
𝑘. 𝑑𝑖𝑘 is the distance between mobile 𝑖 and store 𝑘. The
shadow fading model is given as log-normal distribution of
which standard deviation is 8dB. For the simulation
simplicity, the mobiles’ and stores, maximum transmission
power is limited by 1 watt. The SINR of D2D link between
mobile i and store 𝑘 is give as following:
4. Numerical example
Where M is the number of mobiles using uplink
channel in cellular system and N is thermal noise. S
is the number of stores broadcasting advertisement
on D2D links.
4. Numerical example
The simulation duration is 100 radio frames.
The table shows the average throughput at every radio frame.
The average value is derived from 100 experiments.
AVERAGE THROUGHPUT IN EACH RADIO FRAME
ALGORITHM 1 : SAME RESOURCES ARE SHARED.
ALGORITHM 2: ONLY FREQUENCY DIVISION IS USED.
5. Concluding
1. This paper proposes a way of eliminating interferences from
D2D links.
2. It is expected to upgrade the system when D2D technologies
are fully operational.
3. That the service is limited only to AD and frequency
efficiency is low because it is FFR-based are weaknesses
yet to overcome, which require further studies.