Information Technology Reference
In-Depth Information
Chapter 4
SGUM-based Database Assisted Spectrum
Access
In this chapter, we study the application of the SGUM framework to database assisted
spectrum access.
4.1
Introduction
The very recent FCC ruling requires that white-space users (i.e., secondary TV
spectrum users) must rely on a geo-location database to determine the spectrum
availability [
1
]. Although the database-assisted approach obviates the need of spec-
trum sensing by individual users, it remains challenging to achieve reliable shared
spectrum access, because different white-space users may choose to access the same
vacant channel and thus incur severe interference to each other. To stimulate effective
cooperation for channel allocation among white-space users, we cast the database
assisted distributed spectrum access problem among white-space users with social
ties as a SGUM game.
4.2
System Model
We consider a set of white-space users
N
={
1, 2,
...
,
N
}
where
N
is the total num-
ber of users. We denote the set of TV channels as
. According
to the recent ruling by FCC [
1
], to protect the incumbent primary TV users, each
white-space user
n
M
={
1, 2,
...
,
M
}
will first send a spectrum access request message containing
its geo-location information to a Geo-location database (see Fig.
4.1
for an illustra-
tion). The database then feeds back the set of vacant channels
∈
N
and the
allowable transmission power level
P
n
to user
n
. The ruling by FCC indicates that the
allowable transmission power limit for personal/portable white-space devices (e.g.,
mobile phones) is 100 mW [
1
]. For ease of exposition, we hence assume that each
user
n
accesses the white-space spectrum with the same power level. Each user
n
then
chooses a feasible channel
a
n
from the vacant channel set
M
n
∈
M
M
n
for data transmission.
