Chapter 5
White Space A llocation in
a Co gnitive Radio-Based
High-Speed Vehicle
Network
It is well kn own th at high-speed vehicles, such as high-speed trains, are playing an
increasingly impor ta nt role in people’s lives, since they provide a rela tively stable and
spacious environment f or long distanc e travelers. As a resu lt, there is a strong dema nd
for broadband wireless communications (BWC) f or high-speed vehicles to provide
informa tion access and onboar d entertainme nt services for passengers. However, the
cognitive radio network sho uld be employed to overcome the problem of spectrum
scarcity.
For a cognitive radio network, primary c hannel oc cupancy modeling is very im-
portant for designing secondary user spectrum accessing and scheduling schemes.
PUs in different primary networks usually have different activity mod els, such as in
a cellular network [76], w ireless loc al area network (WLAN) [27], TV/broadca sting
network [7 7], and so forth. However, the existing literature is concerned about static
or low-speed mobile users, and do not consider situations with high-speed mobile
users, in which, the channel availabilities are very different due to the high velocity
of users [78, 79].
75
76
Cognitive Radio Networks
In this chapter, high-speed vehicles are considered for employing the
TV/broadcasting b and via cognitive radio technology to achieve broad band wireless
communications [106]. In a high-speed moving scenario, primary channel occupancy
is mainly depende nt on the secondary user’s position, moving speed, and direction.
Therefore, the relative prim ary channel occupancy m odel, which mainly depends on
the vehicle’s location, velocity, moving directio n, and so on, is considered. Moreover,
a co gnitive r adio-based high-speed vehicle network (CR-HSVN) is introduced and a
framework of the spectrum resource allocation is introduced for effectively utilizing
TV white space.
5.1 A Cognitive Radio-Based High-Speed
Vehicle Network
5.1.1 System Model
In this chapter, we employ the following terms: (1) primary base station (PBS): the
TV signal transmission tower; (2) primary user (PU): the TV set; (3) cognitive base
station (CBS): the CBSs are deployed in the considered area similar to the base sta-
tions in the cellular network, and are m anaged a nd operated by wireless ope rators;
(4) co gnitive vehicle (CV): high-speed vehicle; and (5) cognitive user (CU): the pas-
senger in the CV that needs to access the cogn itive radio network. The main variables
are listed in Table 5.1.
As shown in Figure 5.1 , we assume that there are L PBSs in a certain area, de-
noted as P
l
,l = 1,2,··· ,L. N primary chan nels, denoted as C
n
, n = 1, 2,··· ,N, are
assigned to PBSs to provide services for PUs in the ir coverage ranges. Each PBS
P
l
occupies a fixed and known primary channel C
n
. Note that whe n N 6 L, differ-
ent PBSs may use the same primary channel if they are far away fro m each other.
Locations of these PBSs are known. The coverage radius r
l
of P
l
may be differ-
ent for d ifferent PBSs according to the actu al demand. The PBSs with overlap ped
r
TV signal
transmitter tower
Cognitive
base station
Figure 5.1: The scenario of CR-based high-speed vehicle communication s.

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