Blocking all Receiving Links of Wireless Sensor Network

— Jamming attack is an effective way to disrupt the communication of adversaries. This paper tries to design methods for blocking all receiving links (BARL) of a wireless sensor network (WSN). Firstly the condition for blocking a receiving link is derived and Area for Jamming a Receiving Link (AJRL) is defined. Then BARL jamming method for a network with an unlimited JSR parameter is discussed. Finally, with a limited JSR parameter, BARL jamming attack problems on several networks types, i.e. JN (N, ! N), JN(2,1), JN(3,1) and JN(N, ! 2), are discussed; and jamming methods are presented and proved mathematically respectively.

imize the pair-wise connectivity among WSN nodes. The problem is proved to be NP-complete. The authors present a heuristic algorithm to block the links partially. We focus on blocking all receiving links of a WSN. Cognitive radio has characteristics of fast channel switching and quick response time. In [13], a jammer is used to sense traffics on 802.11g networks and create collisions. The jammer locates at a fixed place. Different from them, this paper tries to search and assign locations for jammers.
The remainder of this paper is organized as follows. The BARL jamming problem is formatted in Section 2. Section 3 solves problem of jamming with an unlimited JSR parameter. Section 4 does BARL jamming with a limited JSR parameter. BARL jamming methods for JN(N,!N), JN(2,1), JN (3,1) and JN(N,!2) networks are presented respectively. Finally, Section 5 concludes the paper.

Problem formulation
We focus on the problem of blocking all receiving links of a WSN. To carry out such attacking, the jammer listens to the open medium and broadcast with the same frequency band [15]. Each node in network has bidirectional communication links.
i k Link ! represents the sending link for i Node and the receiving link for k Node . The jamming power to signal power ratio at the receiver determines the degree to which jamming will be successful. For digital signals, the jammer's goal is to raise this ratio to a level such that the bit error ratio [16] is above a certain threshold. The JSR models [17] at the receiver's antenna are defined as where JT P is the power of the jammer's transmitting antenna; T P is the power of the transmitter; TR G is the antenna gain from transmitter to receiver; RT G is the antenna gain from receiver to transmitter; JR G is the antenna gain from jammer to receiver; RJ G is the antenna gain from receiver to jammer; TR D and JR D are the distance between transmitter and receiver, and the distance between jammer and receiver respectively. The JSR model can be reformatted as When jamming a link, the condition that a receiving link is blocked can be represented as inequality The problem of this paper is similar to the Jammer Deployment Problem defined in [14,18]. For convenience, we define AJRL (Area of Jamming a Receiving Link) to represent an area in which Inequality(3) holds. The WSN works in 3D spaces, therefore the shape of

BARL attack with an unlimited JSR parameter!!
Several ways may be used to increase the JSR parameter!!, such as 1) increasing the power of jammers' transmitting antenna, the antenna gain from jammer to receiver, or the antenna gain from the receiver to jammer; 2) decreasing the power of transmitter, the antenna gain from receiver to transmitter, or the antenna gain from receiver to transmitter; 3) decreasing the threshold ! .In this section we assume JSR parameter! can be increased unlimitedly.

BARL attack with a limited JSR parameter!!
Usually only a limited JSR parameter is available when attacking a WSN. In this section, we discuss the BARL attack problems on

Attacking !"!!! !!network
Whether BARL attack can be launched on        (5) (5) As shown in Figure, Line be the line segment between i Node and k Node . If place the jammer on any point on ik Line , inequality (7) and (8) Equality (10) gives out the lower limit value of JSR parameter ! , which needed to block all receiving links. Method 4is introduced to search the lower limit value of ! and the position for the jammer.
Step 1-2 initialize JSR parameter's upper bound ub and lower bound ul to 10 and 0 respectively. Step 3 sets variable jamall to false (unable to block all receiving links).
Step 4 starts a loop to look for lower JSR parameter which can be used to block all receiving links.
Step 5 calculates the mean value of ub and ul , and assigns it to variable ! . Step 6 selects minimal distance of ik d , kq d and iq d , and assigns to min d .
Step 7-9 draw three spheres with centers locating on i Node , k Node and q Node respectively. All spheres have radii of min d ! .
Step 10 checks whether intersection existed among the three spheres. If existed, all receiving links can be blocked using current JSR parameter ! . So ub is set to ! (step 11) and jamall is set to true (step 12). Otherwise, ul is set to ! (step 14).