Reliability Research of Wireless Sensor Network Node

Shuxia Pan Department of mathematics,

Jilin Medical College, Jilin, China

E-mail:pan4652405@163.com

Bingbing Ji,Yali Luan Department of information engineering,

Northeast Dianli University Jilin, China

E-mail:dice611@163.com

Abstract—In this paper, it proposes a new energy-efficient, reliable topological clustering algorithm (ERCTNA), which analysis the reliability of wireless sensor networks at the present stage factors and improve the original LEACH protocol. ERCTNA algorithm can balance the cluster head of energy load and increase the reliability of the network topology through setting up auxiliary cluster head node and optimizing information transfer mode. This model improves the traditional long-distance communication in wireless sensor networks to bring the energy of the excessive wear and tear issues, effectively extending the life cycle of the entire network to improve the reliability of wireless sensor networks.

Keywords-wireless sensor network; node reliability; cluster

I. INTRODUCTION For the purpose of monitoring, the goal of wireless sensor

network (WSN) is to obtain reliable information, and reliably transfer the information to the observers. Because of the limited energy resources and poor environment, some WSN nodes will not work normally. In addition to this, the intruder would also undermine the wireless sensor network. These factors will seriously affect the reliability of the whole wireless sensor network. For its performance, reliability is a very important evaluation. At present, the reliability study mainly analyze the changes in network performance, which affected by the communication nodes and links not work affectively.

II. PROBLEM ANALYSIS The nodes in the wireless sensor network can easily be

damaged or death due to energy depletion and damaged. This feature in the cluster network is particular apparent, the cluster head’s death will cause all nodes in the cluster not available. At the same time, it will greatly affect the entire wireless sensor network reliability. LEACH is a kind of self-organizing, adaptive clustering protocol [1]. In each round, LEACH randomly chose some nodes to become cluster head node, and continue to the role of cluster head rotation to make the energy of the entire sensor network load to achieve fair. WSN nodes in the cluster send data to the cluster head nodes, and the cluster head nodes integrate and process the data.

As a basic cluster agreement, in the energy efficiency ,LEACH has three disadvantages [2]:firstly, the cluster head

node has more than ordinary tasks, such as acceptance within the cluster node information, integration of data and sending data to the base station node; secondly, the cluster head far away from the base station must pass the long-distance means of communication to send data to the base station, which easily lead to the premature death of these cluster head nodes; lastly, as for the cluster size of asymmetry, it will cause the cluster heads which have too many cluster nodes within the cluster heavy energy load. The above three factors will lead to the premature death of some sensor nodes. In recent years, there are a lot of improvements for LEACH algorithm [3].

BCDCP is a kind of central control of the routing protocols, by the base station is responsible for the establishment of clusters and chooses of the routing, BCDCP uses CH-to-CH routing mechanism. But the cluster-heads energy load is still heavy, could not avoid the premature death of some nodes. The agreement referred to above there is a common problem: in each round, the cluster head of the energy overload makes the need to frequently re-group clusters in order to avoid premature death of some nodes. But the group of clusters caused by frequent communication cost is very high. And if attacked, the cluster head will lead to all the nodes within a cluster can not be used, which will greatly affect the wireless sensor network reliability [4].

To solve the above shortcomings, we propose new Energy-efficient, reliable cluster topology network algorithm (ERCTNA). Within a cluster, we set up a special node, called the secondary cluster head node. The cluster node auxiliary node not only increase the reliability of the network bus also make the contribution energy conservation.

III. ALGORITHM DESIGN

A. Cluster Head Node Select Algorithm In the simulation, we assume that there are n sensor nodes

uniformly distributed in the M × M square area. ERCTNA algorithm uses the LEACH mechanism to select the cluster head nodes. In LEACH protocol, each sensor node decides itself whether as a cluster head in this round. The algorithm by all nodes rotation as cluster head node in network ensure the load in the network more evenly distributed, to maximize the network survival time. First, node n selects the random number between 0 and 1, when the random number is less

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Proceedings of the 2010 14th International Conference on Computer Supported Cooperative Work in Design

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( , )TxE k d

*elecE k * * namp k dε *elecE k

( )rxE kd

than threshold T (n), the node becomes a cluster head node in this round.

Threshold is defined as follows:

p1 [ mod(1/ )]( )

0,

n Gp r pT n

� ∈� − ×= ��� ot her s

(1)

Here, P, r and G denote the network called for the percentage of cluster head nodes, the current round number and G (t) as a direct equation, indicate the node collection that in the last 1 / p rounds not been cluster head, respectively.

Be elected as cluster head node, the node sends a broadcast packet outside, including the cluster head message id number. Non-cluster head nodes receive the broadcast information according to the strength of the signal as their own whether to join the cluster basis. Then each non-cluster head node sends a "decide-to-to-join-the-cluster" of information packets to the cluster head of their choice.

B. The Choice of Cluster Head Auxiliary Node The nodes of receiving a number of cluster head

broadcasting information record their total number of cluster head neighbor and neighbor cluster head id information in the "decide-to-to-join-the-cluster" and their distance from the base station node and its own energy the size of the text, then send the newspaper to their cluster head. Cluster-heads receive all the information within the cluster will use the information support the election of two cluster head nodes. The selection criteria are: high energy, nearest the base station, with more than a neighbor cluster head. Cluster-heads to support the elected cluster head node sends a "CH-assistant-node-appoint" message to the elected cluster head auxiliary node. This message will record the number of nodes in the cluster. Secondary cluster head nodes receive the packet, it was found above a threshold cluster size, will be told foreign broadcasts within a cluster node can re-select themselves as cluster heads. Thus to avoid the existence of clusters is too large.

C. Data Collect Mechanism In ERCTNA, the network working hours same as the

LEACH protocol is divided into rounds, each round is divided into the initial establishment phase and the stable stage. The initial stage of the establishment phase clusters. A stable stage of data transfer phase. In ERCTNA the steady-state phase points are divided into five time slices. In the beginning of each time slice when the cluster head auxiliary node will send a message through the cluster head checks cluster head is not working properly. If the cluster head auxiliary node, within the specified time, has not been cluster head node response information, the first auxiliary node in the cluster that the cluster head can no longer be available. At the time, cluster head auxiliary node sends a broadcast request packet to all nodes in cluster head re-send their information.

D. Optimization Transfer Mode Most agreements take a single hop or multi-hop approach

to transmit data. As shown in Fig. 1, node A sending a

message to node C can choose a single jump directly transmit to C, can also first transfer message to node B, from B to Node C, the multi-hop transmission. In this section, the paper will analysis theoretically which transfer mode most energy-efficient. In this paper, the literature [5] proposes the model shown in Fig. 2.

Figure 1. Single-hop VS Multi-hop Transfer Mode

Figure 2. Wireless Transmission Energy Consumption Mode

In this model, we must transmit k-bit message, d m distance need to the energy consumed as follows:

20

40

,( , )

,elec fs

txelec mp

kE k d d dE k d

kE k d d dεε

+ + <��= � + ≥�� (2)

elecE are the energy consumption of the circuit parameters by digital coding, modulation, filtering and signal spreading and other factors; fsε and mpε are the amplifier energy consumption parameters; 0d is a fixed threshold, the model value of 75 m.

Receive k bit of information, need to consume energy as follows:

_( ) ( ) *rx rx elec elecE k E k E k= = (3)

Definition: When the distance between two nodes greater than 0d , the communication between these two points is called long-distance communications; when the distance between two points is less than 0d , the communication between these two points is called short-distance communication.

1) case 1: d <= 0d 2

_ _ ( , ) ( )one hop short tx elec fsE E k d k E dε= = + (4)

2 2_ _

0 0

( , ) ( , ) ( ) ( ) ( ) *

,two hop short tx tx rx elec fs elec fs elecE E k r E k s E k k E r k E s k E

r d s dε ε= + + = + + + +

< < (5)

In (5) r and s are less than 0d . one-hop short-distance communication is less than two short-distance communication if and only if:

_ _one hop shortE < _ _two hop shortE (6)

445

2( )elec fsk E dε+ < 2 2( ) ( ) *elec fs elec fs eleck E r k E s k Eε ε+ + + + (7)

2 2 22*( )elec

fs

Ed r s

ε< + + (8)

If the (7) sets up, requires 2 ( / )elec fsd sqrt E ε< × , time / 2r s d= = . By induction, we know that these conclusions for the same multi-hop short-distance communication are established. Finally, we get when d is less than 2 ( / ) 141.42elec fssqrt E ε× = m, the one-hop short-distance communication more energy-saving than multi-hop short-distance. However, the conclusions of the establishment of conditions for d less than 0d , in the mode 0d =75 m <141.42 m. Therefore, final conclusions are as follows, in the short-distance communication, one- hop communications more energy savings than over multi-hop short-range communications.

2) case 2: d> 0d (two-hop-short VS one-hop-long) We know that when 0d d> , the long-distance

communication needs are far greater than the energy consumed by short-distance communication ( 0d d> ), in this section we will analyze the short-distance communication and multi-hop-hop long distance communications who is more energy efficient. First, we consider two short-distance communications instead of hop distance communication. Hop long distance communications than the two-hop short-distance communication is more energy-efficient if and only if:

_ _ _ _one hop long two hop shortE E< (9)

4 2 2( ) ( ) ( ) *elec mp elec fs elec fs eleck E d k E r k E s k Eε ε ε+ < + + + + (10)

4 2 2 2*( )fs elec

mp mp

Ed r sεε ε

< + + (11)

Therefore, if (10) sets up, the right side, 4d must be less than the minimum. And circumstances of a similar, because

4d can not be negative, so there is:

2

0

2( ) 4*2 2

104.422

fs fs elec

mp mp mp

E

d d

ε εε ε ε

+ +

< < = (12)

Here, we get a value of 104.42 m. In the simulation, we put 0d as a threshold. Used in a mixed communication to determine threshold.

3) case 3: 0d d> (two-hop-mixed VS one-hop-long) Next, we analyze the situation with the one-hop short

distance and one-hop long distance communications instead of one-hop long distance communications.

_ _ _ _one hop long two hop mixedE E< (13)

4 2 2( ) ( ) ( ) *elec mp elec fs elec mp eleck E d k E r k E s k Eε ε ε+ < + + + + (14)

4 2 2 2 2*( ) 2fs fs elec

mp mp mp

Ed r s rsε εε ε ε

< − + + (15)

When the right of (14) takes the minimum, There 2( / )elec fssqrt E r sε = , and 2( / )elec fssqrt E s s dε + = , (14) equals to:

2 4 4 2*( ) 2mp elec

fs mp

Es s s

εε ε

+ < + (16)

3 12 8 7 6 5 42 2

2*( ) 2*( ) 6*( ) 4*( ) 0mp mp mp mp elec

fs fs fs fs mp

Es s s s s

ε ε ε εε ε ε ε ε

+ + − − < (17)

By calculated, this high-level inequality is not real solution. Therefore, the one-hop long distance communications can not be more energy-efficient than the mixed-transfer mode of the one-hop short distance added the one-hop long distance.

Finally, according to case 3, the analysis results, we get the following optimization of transfer mode rules:

a) When the distance from node to base station meet 0d d< , we jump straight to short-distance communication

method; b) When the distance from node to base station meet the

0 1d d d< < , use the one-hop long distance communications style;

c) When the distance from node to base station meet the 0d d> , node is the data transmission, use the intermediate

nodes multi-hop transmission, the transmission node and intermediate nodes based on rules a) and b).

In this cluster agreement, mixed transmission of specific principles are as follows:

d) When the distance from node to base station meet 0d d< , using the one-hop short distance transmission;

e) When the distance from node to base station meet 0 1d d d< < , using one-hop long-distance transmission;

f) When 1d d> Cluster head node uses cluster head auxiliary node and auxiliary head neighbor cluster head as intermediate nodes to the base station transmit data, rules with d) and e).

After cluster head collect information within the cluster, firstly fuse data, and then according to the above-mentioned principles of transmission sent the fusion data to base station. The cluster head auxiliary node for data transmission, also follow the principle of optimization of transmission.

IV. SIMULATION RESULTS In this section, we conduct a simulation algorithm

ERCTNA them with LEACH and BCDCP protocols were compared as shown in Fig. 3. The parameters are as follows: the base station location (50 m, 175 m); threshold distance

0d =75 m; threshold distance 1d =104.42 m;

446

elecE =50 J/bit, daE =5 J/bit/message; fsε =10 pJ/bit/m2; mpε = 0.0013 pJ/bit/m2 Message size =4000 bit; nodeE =1 J.

Figure 3. The number of nodes in the survival changes over time

Figure 4. Netwrok survival time changes with the number of nodes

Figure 5. The number of network packets loss with the changes in the percentage of node death

Fig. 3 a) and Fig. 3 b) are all nodes at intervals. In the simulation, when the node's residual energy is less than 2 ‰ the initial energy, we believe that the node death. If we define the survival time of the network for the round number of the first node deaths, from Fig. 3 a) and Fig. 3 b), we can see the network ERCTNA survival time is longer than LEACH and BCDCP. By comparing these two maps, as the network coverage increasing, ERCTNA relative to LEACH and BCDCP survival time advantage becomes more apparent. The reason is that ERCTNA adopted a relatively flexible multi-hop transmission mode, thereby reducing the long-distance communications brought about by excessive energy loss. ERCTNA transfer mode optimization in energy saving advantages as the network size increases the performance becomes more apparent. Fig. 4, different network size, is the round number of the first node death. From Fig. 4, in different size of network performance, ERCTNA is better than LEACH and BCDCP in energy saving. ERCTNA network survival

time is more than LEACH and BCDCP 22%, 19%. In the simulation, we artificially make the percentage of nodes in a different random death. Numbers of nodes in the network are 200. Fig. 5, for 50 rounds, not using the percentage of attacks, is the network packet loss conditions. We can see from Fig. 5, with the malicious attacks on the nodes increases, a sharp increase in the number of packet loss. By setting the cluster head auxiliary node, the ERCTNA number of packet loss was significantly lower than LEACH and BCDCP. With the increase in the percentage of dead nodes, LEACH and BCDCP, the number of packet loss is always more with ERCTNA. From this we can conclude that, in the case of malicious attacks, ERCTNA is more reliable than LEACH and BCDCP.

V. CONCLUSION In this paper, we propose and evaluate a new energy-

efficient, reliable topological clustering algorithm. First, this paper point out the LEACH and BCDCP protocol deficiencies, then introduce the ERCTNA main design idea, and then describe in detail ERCTNA algorithm process. In this paper, through setting cluster head auxiliary node, the ERCTNA effectively solute the trouble which clusters head damaged to the network, balance the energy load of the cluster head and increase the reliability of the network topology. Taking into account the limited energy of sensor nodes, we use a new transmission mode between cluster head, cluster head auxiliary nodes and the base station. This model improves the traditional long-distance communication in sensor networks to bring the energy of the excessive wear and tear issues, effectively extend the entire network life cycle. Theoretical analysis and simulation results show that the network ERCTNA survival time better than LEACH and BCDCP. In the case of malicious attacks, ERCTNA also have excellent reliability performance.

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[3] Shen Bo, Zhang Yong, Zhong Yi-ping, “Wireless sensor network clustering routing protocol,” Journal of Software, Vol.17, NO.7, pp.588-1600, July 2006.

[4] De S Qiao C Wu H, “Meshed multipath routing: An efficient strategy in sensor networks,” Wireless Communications and Networking (WCNC2003). IEEE.Vol3, pp.16-20.

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