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。

cell

群組(cluster)

2. System model

Allocated Frequency Bandwidth in Each Area

可使用頻率

地區

全部頻寬

2. System model

Interference Model

3. How to assign D2D link resource

Step 1 : Interference cancellation between cellular link and

D2D linkTo 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

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 get

rid of the cellular link-driven

interferences on D2D link.

D2D Belt

Step 1 : Interference cancellation between cellular link and

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 resourceStep2 : 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 resourceStep2 : 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 exampleSUBFRAME ALLOCATION EXAMPLES (R=3, W=2)

1) R = frequency reuse factor2) i = AD D2D link of cell3) n=i mod R4) x=n*w (D2D AD window : w)5) from the subframe a, the service is provided for the time

of w and satisfies a=x mod 106) first service is given, continuously at the interval of T,to

RF that satisfies RF mod T = FLOOR(x/10)

4. Numerical exampleThe link gain between mobile and store , is given by . is shadow fading factor between mobile i and store . is the distance between mobile and store . 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 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 exampleThe simulation duration is 100 radio frames. The table shows the average throughput at every radio frame. The average value is derived from 100 experiments.

ALGORITHM 1 : SAME RESOURCES ARE SHARED.ALGORITHM 2: ONLY FREQUENCY DIVISION IS USED.

AVERAGE THROUGHPUT IN EACH RADIO FRAME

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.