KR101039581B1 - Routing for Enhancing Source-Location Privacy in Wireless Sensor Networks - Google Patents

Abstract

In a wireless sensor network that supports troops performing operations on the battlefield or monitors the ecology of rare animals, messages to protect the content of transmitted information as well as the location of such management or assets from enemy or malicious tracking. A routing method for enhancing location confidentiality of a source that is a node) is disclosed.

Routing method for strengthening the source location confidentiality in the disclosed wireless sensor network, the first step of performing a greedy transmission technique for the shortest distance routing and a random routing technique for randomly deploying a path for a certain hop with a predetermined probability; And performing a second process of bypassing the boundary area to protect the position of the dormant source from chasing by the tracer when the dormant sources are close to where the dormant sources exist during the first process. By minimizing the number of hops, the location protection of the message transfer source can be increased.

Wireless sensor network, source location protection (confidential), routing protocols, safety periods, propagation delays

Description

Routing for Enhancing Source-Location Privacy in Wireless Sensor Networks}

The present invention relates to routing that enhances location confidentiality of a managed or monitored object (hereinafter referred to as "managed object" or "protected object") in a wireless sensor network, and more particularly, detection (or specific) from a managed object. Location confidentiality of a node transmitting data to a base station (hereinafter referred to as an "active source") and if the tracker is within a certain distance, even if it is not transmitting information to the base station, the location will be A method of routing in a wireless sensor network for preserving location confidentiality of nodes adjacent to managed objects (hereinafter referred to as "dormant sources").

The development of wireless communication technology and the wide spread of sensor technology have enabled the construction of wireless sensor networks that organically connect a large number of devices. In particular, various applications are being actively researched and developed for the purpose of collecting and controlling data in the defense, transportation and environmental fields. Sensor devices, called network nodes, generally have limited computing power and resources. These nodes serve as sources that deliver events or processed data detected from the installation environment to a base station or sink node using a multi-hop path. Conversely, it receives information from the base station and transmits or controls commands to related objects or devices in the installation environment. Therefore, timely data collection and efficient real-time communication that can be controlled is essential.

However, for the successful operation of the sensor network, security problems cannot be overlooked in that wireless communication itself has a transmission signal exposure problem, standardization of related equipment, and installation space may be outdoors. In addition, some applications cannot rely on encryption techniques to protect the content of the transmitted information to maintain a successful security scheme. For example, in a sensor network that supports mobile objects such as troops or tanks operating on the battlefield, even if the transmission message is encrypted and confidential about its contents, the location of the node corresponding to the source of the information is exposed to the enemy. This can seriously threaten troop survival or equipment loss. In addition, sensory networks that monitor rare animal activity should not expose protected animal location information to poachers. For this reason, researches for protecting contextual information such as the location of the information generating node, the amount of traffic, the type of traffic, the type of transmission and reception, and the like have attracted attention.

A base station is a node that is the center of a sensor network, and information transmitted from various nodes is concentrated, and its presence can be easily exposed or detected as a device connected to an external server or a network. Therefore, routing has been studied to protect the location of the source node transmitting information to the base station when the location of the base station is known.

The research on the location protection of source nodes at the routing level in sensor networks has been very active since the Phantom Routing (PR) was presented by W. Trappe's team at WINLAB, Rutgers University. PR can be traced back to the source of a message that arrives at the tracker, or local eavesdropper, that is near or on the base station while transmitting the collected information to the base station. It is designed to counteract a reverse hop-by-hop attack.

At the beginning of the routing, a random walk phase over a predetermined distance (eg, 15 hops) is randomly selected (random walk phase), and the second half performs a routing phase of delivering a message to a base station. In the routing process, a single path PR-SP (single path) by an algorithm or a PR-B (broadcast) for broadcasting is used. Subsequent studies defined a location protection model and addressed the performance of PR when the source node moves and when the tracer waits for a message at a certain location. It is very encouraging in deriving the problem of source location protection at the routing level and establishing evaluation criteria with alternatives. However, as the arbitrary travel distance increases, the safety period increases, but there is a problem in that message delivery is excessively delayed in proportion thereto. In addition, it is very likely that the order of arrival at the destination will be reversed if the burden of establishing a new path every time the message is transmitted and if the transmission messages occur continuously.

On the other hand, the way in which the direction of nodes selected in the process of moving from PR to the arbitrary direction does not cancel each other and is developed away from the source, and the method of setting the path and transmitting the message by using PR from both the source and the sink at the same time, etc. Follow-up studies were presented. In addition, studies have been proposed to overlap setting paths with other paths in the middle to cause confusion in tracking. However, they all considered only active source nodes and did not provide an alternative to the propagation delay problem that occurs when using long paths to increase safety periods.

The CEM (Cyclic Entrapment Method) is a method for increasing the safety period but shortening the propagation delay. By adding loop paths of a certain length (e.g. 10 hops) or more to nodes on the path established by the shortest distance algorithm between the message transmitting node and the base station, the message being sent will traverse the loop as well as the original shortest path, causing confusion in tracking. To give.

You can shorten the transmission delay, but you can avoid looping if the attacker remembers the coordinates of the GPS or the node it tracked. In addition, some nodes are used as paths, but only a few nodes or all nodes have to set a loop longer than a predetermined length at the time of network initialization. Considering that the k-longest path problem of setting the path with a minimum length of k or more is NP-complete, the loop construction time is also a burden. In addition, when a tracker approaches a node connected to the loop, a cheat message must occur from the loop to attract the tracker into the loop. The question is how to implement an effective mechanism for determining the tracker's access to a generic small node. For example, it is not a simple matter of installing a camera for recognizing a tracker in a sensor node having a physical size, processing capacity and storage space, or how to recognize a tracker that is not known in advance. After all, loop utilization, the core of CEM, is problematic in its effectiveness.

Meanwhile, research has also been conducted to protect the location of the final destination node or base station of the message. For example, there is a Differential Enforced Fractal Protocol (DEFP) in which an attacker staying around an aggregator node where traffic destined for a base station meets attempts to locate the base station through traffic collection and analysis. This method causes nodes on the path to branch at a certain probability into a fractal propagation phase in a tree form, and random movement is performed at a certain probability to induce randomization of the usage path. In addition, techniques for protecting information such as traffic type, amount of information, frequency of occurrence, etc. have been comprehensively studied. Techniques for generating fake messages or random movements are widely used in subsequent studies.

Location Privacy Routing (LPR) is an extended form of DEEP, and, in contrast to PR-SP, is a routing protocol for enhancing the location protection of the destination node when the location of the source is exposed. Probabilistic random random walks are performed to allow the tracer to be departed from the destination node in consideration of the function that occurs in parallel with the deception false message. LPR with excellent location protection of the destination node cannot be directly applied for source location protection. The biggest reason is that the cheat message generation feature is not available to attackers who are chasing back from the base station to the source. In other words, the cheat message should be generated exactly where the tracker is located. Unlike the source location protection where the tracking message and the tracking direction coincide with each other, the source location protection requires that each node has a function to recognize the tracker. In other words, as in CEM, it should be able to solve the problem of fake synchronization, which should generate the cheat message exactly at the point of recognition of the tracker. Otherwise there is a burden of constantly generating cheat messages. Compared to the PR-SP which does not use the cheat message, the message generation problem caused by the cheat message also makes it difficult to apply to source location protection routing. In addition, the message propagation delay problem due to the length of the path used in the LPR should also be improved.

In addition, there are studies on location protection in a global eavesdropper model in which trackers (monitors) are located in various places in the network and information is collected and analyzed, and anonymity communication using encryption techniques is also studied. Various security issues in wireless sensor networks, in particular all issues related to routing and an overview approach, are described in Karlof-Wagner's paper. In summary, although there is no information transmission, a more generalized location protection routing scheme is needed when there are management or monitoring targets that should not be exposed, that is, dormant source nodes. In addition, this approach should be able to reduce message delivery delays while increasing the level of location protection.

Accordingly, the present invention has been proposed to solve various problems arising in the method for protecting the location of the final destination node or base station of the existing message,

The problem to be solved by the present invention is to preserve the location confidentiality of the protected objects by strengthening the location confidentiality of the nodes adjacent to the protected or managed objects if the tracker closes within a certain distance even if the information is not transmitted to the base station. At the same time, it provides a routing method that enhances location confidentiality of the source of a message.

Another problem to be solved by the present invention is that when the number of transmitted messages is not determined and, in some cases, it is possible to know in advance what constraints are required for enhanced location protection of the source, thereby finding a realistic alternative. It provides a routing method to enhance source location confidentiality in a wireless sensor network.

Another problem to be solved by the present invention is to perform the routing technique for shortest distance routing and the routing technique for randomly deploying a route for a certain hop, so that the path length does not increase excessively, and dormant sources It is to provide a routing method for strengthening source location confidentiality in a wireless sensor network in which a location of a source can be bypassed when it is close to the source, thereby protecting the location of the source from the pursuit of the tracker.

The preferred embodiment of the "routing method for strengthening source location confidentiality in a wireless sensor network" according to the present invention for solving the above problems,

Performing a greedy transmission technique for shortest distance routing and a routing technique for randomly deploying a route for a predetermined hop with a predetermined probability;

In the case where the dormant sources are present while the process is performed, the method includes bypassing the source to protect the source from chasing after the tracer.

Further, the "routing method for enhancing source location confidentiality in a wireless sensor network" according to the present invention,

In the case where the number of transmitted messages is not determined and in a predetermined case, it is preferable to further include a step of preliminarily knowing what constraints are required for perfect location protection of the source.

According to the present invention, even if the information is not transmitted to the base station, if the tracker approaches within a certain distance, the location of the trajectory is advantageous in that the location confidentiality of the nodes adjacent to the management objects can be enhanced.

In addition, when the number of transmission messages is not determined and in some cases, it is possible to recognize in advance what constraints are required for the perfect location protection of the source, and thus, there is an advantage of seeking a realistic alternative.

In addition, by performing a routing probability for shortest distance routing and a routing technique that randomly deploys a path for a certain hop, the path length can be prevented from being excessively extended, and the dormant sources are located close to each other. In this case, the bypass has the advantage of protecting the source from chasing after the tracer.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

First, a brief description of the network and tracker hypothesized to address the source location protection routing problem in a wireless sensor network is provided.

Network Model

There are N (> 0) sensor nodes in the network, and the signal reach of each node is r (> 0). Use multi-hop routing through nodes that are different from nodes that are out of distance r. It is assumed that every node knows its position (that is, its coordinates). No error occurs during transmission, and all messages sent and received between nodes are encrypted and cannot be decrypted by an attacker. In addition, it is assumed that there is one base station in the network and the location of the base station is exposed to the attacker.

The occurrence interval of the transmission messages at the source node transmitting the message to the base station assumes a model (technically referred to as a "low-duty cycle" model) longer than the time it takes for the transmitted message to arrive at the base station. When the network is initialized, the base station broadcasts a message throughout the network including various coordinate information related to location protection with its coordinates. All nodes which receive this get necessary control information such as the coordinates of the base station and the shortest hops to the base station.

Attacker (Tracker) Model-

The attacker is a local eavesdropper and is a fully passive attacker that does not interfere with the communication between nodes. It can detect the signal of transmission message on the same way as a normal node, but it has additional equipment such as spectrum analyzer, directional antenna, GPS, etc. to measure signal direction, strength, time of arrival, etc. Suppose you can. As a result, the message is tracked by hopping along with the message arriving nearby, and does not move to another node in advance of the generated signal. Pursuit always follows the signal that arrives first, and randomly selects one only if several signals occur simultaneously. In other words, it is a "patient model" that waits until the next signal occurs almost indefinitely (for a limited enough time for simulation) at the node passing through during the tracking process.

If an attacker enters a circle with a radius of α from where the source exists, the source's position is considered to be discovered. The area at this time is called an exposure area and α is an exposure or capture distance. That is, if the current coordinates of the source s and the attacker a are represented by L (s) (= (xs, ys)) and L (a) (= (xa, ya)) respectively, | L (s) -L (a) | If ≤ α, the position of s is exposed to a. α varies according to the attacker's tracking ability or what is being protected or managed. For example, people's sight distance or signal detection distance of equipment used.

-Summary on Source Location Protection-

Theoretical conditions for the complete protection of the location of the message transfer source are presented. For convenience, we assume the simplest case where there is no dormant source in the network and only one active source. First, when a specific event is detected in the source and transmitted to the base station. The next case is to send only a limited number of pre-tuned T messages.

Theorem 1: A node s is sent to base station b as soon as a message occurs. The maximum number of messages that s can send while fully protecting its position for an attacker a with the hop-unit chase capability defined _as above does not exceed h _as- [α / r]. Where h _as is the number of hops in the shortest path between a and s, α is the exposure distance, and r is the reach of the transmission signal. [x] represents the smallest of integers greater than or equal to x.

Attestation: Tracker a can move 1-hop each time it receives a signal from a message being sent during tracking. The hop count of the shortest path from where a is to s is h _{a -s} . Therefore, regardless of which algorithm establishes the path between s and b, the attack is successful if a approaches within s within a minimum [α / r] hop. Therefore, in any case, source s must not send more than h _{a -s-} [α / r] messages in order to protect its location.

Theorem 2: The number of messages a node s sends to base station b is said to be T (> 0). Then the problem of s sending T messages with minimal propagation delay (i.e. using the minimum number of hop paths) while fully protecting their position from tracker a is NP-complete (a computer-aided process If a problem is called NP-complete, it means a difficult problem that requires astronomical calculations, which theoretically does not provide an optimal solution).

Proof: For convenience, assume that the number N of nodes in the network is large enough so that T <N. If the number of hops of the shortest path R1 from node v to s to _a is h _{a -s} , the relationship 1 (h _{a -s-} [α / r]) ≥ T must be established by theorem 1 so that the position of s is not revealed and T All messages can be sent safely. However, if (ha _-s- [α / r]) <T, then the shortest path R ₁ of node s from node v where a currently resides requires that T messages be sent via path R ₂ , which satisfies The position of s can be protected. The length of the path from v to s must satisfy (h _{a -s-} [α / r]) + Δh _{a -s} ≥ T. In general, the "k-th longest path problem" of finding a path that is at least k or more in length is known as NP-complete. Therefore, finding the path R ₂ whose path length is (h _as- [α / r]) + Δh _{a -s} ≥ T is also NP-complete.

In reality, if every node, including the source, knows the attacker's current location, you can avoid this and send more messages because you can set longer or more paths. However, assuming that the network under consideration is composed of thousands or tens of thousands of nodes, it is impractical to implement the ability to locate the attacker's movements on all nodes. If you have a separate server or external device that manages the tracker's location and use it, the security threats and communication costs associated with it will also be small. In addition, it is clear from the above theorem that it is impractical by Theorem 2 to find an algorithm that finds the path of least delivery cost while guaranteeing the location of the message transfer source even if the attacker's location is known. Therefore, it is necessary to study a routing scheme that delivers more messages through a short delay time before the location is exposed, rather than a routing technique that guarantees 100% the source location protection capability of the routing protocol.

Accordingly, the present invention proposes a GSLP-w (GPSR-based Location Privacy with crew size w) as a routing scheme for reducing the message propagation delay as much as possible and enhancing the source location protection capability.

Briefly, the approach is based on the consideration of nodes that are close to the target, that is, dormant sources, and a mix of probable next-hop nodes.

Existing researches on source location protection routing consider the case where there is only one source node that detects an object or event and delivers information from it. However, in applications using the sensor network, there are many cases where there are many things to be monitored or protected. In addition, in applications that support targets such as troops or tanks on the battlefield, the location must be protected from attackers or trackers regardless of communication with the base station.

For example, consider a case where soldier 1, soldier 2, soldier 3 and the location tracker adversary corresponding to three soldiers exist in the radio cells of nodes e, f, g, and h, respectively, as shown in FIG. In the situation where node e adjacent to soldier 1 on the top right is currently sending a message to the base station, the adversary staying near the exposed base station has moved three hops back in response to the signals of the arriving messages ( assuming the adversary starts tracking from the base station). That is, it is assumed that three messages are transmitted from the node e since the 1-hop movement is assumed per message. On the other hand, the currently used route is via node g, which includes soldier 3 in its wireless cell, which is two-hops away from the node where the attacker is located. If node e, who does not know this, sends one more subsequent message, the tracker will enter node g's radio cell and soldier 3's location will be exposed to the attacker (the attacker's detection distance can be up to signal transmission distance r). At home). Then, if seven subsequent messages are further sent from node e, the position of node e itself is also revealed and in danger. Therefore, a routing algorithm must be developed that starts not within a certain distance of the location of node e transmitting the message, as well as the objects of the night that need protection of the path used by the transmitted message (ie soldier 2 and soldier 3). . In addition, these algorithms do not use attacker's location, network topology, or centralized path information when enjoying the theorem of the previous chapter, and all nodes have limited information (e.g. their own coordinates, coordinates of neighboring nodes). Only the source and coordinates of the destination node, etc.).

For ease of discussion, a node such as node e in Figure 1 that transmits detected events or processed information to a base station is defined as an "active source." Adjacent nodes, i.e., nodes f or g in FIG. 1, are defined as "dormant sources." By definition, an activity source can be thought of as containing the concept of a dormant source. In the present invention, there is only one active source at any time in the network, assuming one corresponding sensor node per protected object. That is, sensor nodes corresponding to the protection targets have a one-to-one relationship. The coordinates of the node corresponding to the object to be protected are sufficiently close to within the allowable error so that "the position protection of the source coincides with the position protection of the object to be protected". In other words, the location of a node corresponding to an active source or a human source is exposed to mean that the presence of a protected object existing in the radio cell set by the source node is also exposed.

Meanwhile, an alert zone is set as shown in FIG. 2 so that the path established in the location protection routing process bypasses the dormant sources without being within the exposure distance. A node that detects the appearance of a protected object, that is, a dormant source, first locates a node within an alert zone whose radius β (> α) includes an exposed area of radius α around the protected object. Indicate nearby. This process is assumed to be performed by existing geocasting or scoped flooding, and it is assumed that the content of the message used is also safe from attackers using encryption techniques. The border zone is a buffer zone of the exposed area. For example, if the node density in the network is low, the value of β can be increased to prevent the inflow of messages into the exposed area. The larger the border, the safer the location of the source.

The first part of the PR-SP is strictly divided into two stages: the process of developing a route to an arbitrary place in a random walk and the second part of the process of delivering a message to a destination. Therefore, in order to increase the safety period, the random mode part of the first half had to be lengthened. This soon created a burden of delay in delivery. In the proposed GSLP-w, a next-hop node, that is, a message forwarding node, is selected as one of three modes as shown in FIG. 3.

Referring to FIG. 3, a routing method for enhancing source location confidentiality in a wireless sensor network according to the present invention will be described in detail as follows. However, in the following description, AZ (z) indicates a set of boundary region nodes set by a certain human source node z.

First, when the current node u receives the message M from the neighbor node t (S101), the field TTLrw indicating whether the random mode is continuously performed is examined (S103).

As a result of this investigation, if TTLrw> 0, the system enters a random mode and selects a next-hop node v (S105). In this mode, random mode selects a next-hop node to transmit a message of a node that does not exist in a boundary area set by another node without increasing the physical distance (not the number of hops) to the destination compared to the current node. . That is, the node | L (v) -L (b) | ≤ | L (u) -L (b) | is selected (S105). If the selected v is v ∈ AZ (z) for any node z, switch to the perimeter mode (S111) with TTLrw = 0, otherwise perform TTLrw = TTLrw-1 S109) Send the message M to v. Once the random mode is started, it must indicate whether it is performed in the message M delivered so that the same process can be continuously performed by the maximum TTLrw hop for subsequent nodes (FIG. 4A). On the other hand, if the border region is encountered at any time during the random mode application, it is converted to the parameter mode (S111) .The effect of the random mode is that various nodes can be used in different paths. For example, the greater the probability p _{rw -s} to switch from the greedy mode to the random mode, and the larger the TTL _rw , the paths composed of various nodes may be initiated.

On the other hand, when the TTL _rw in the message M that arrives as shown in S103 of FIG. 1 is not TTL _rw > 0 (that is, TTL _rw = 0), the random mode has a probability p _{rw -s} (0 <p _{rw -s} <1). Enter On the other hand, the probability (1-p _rw-s ) continues the greedy mode to select the neighboring node v closest to the destination (S113 ~ S117). This is described in detail as follows. In greedy mode, a random number p (0 <p <1) is generated for a given p _{rw -s} and once it satisfies p≤p _{rw -s} , it switches to random mode, otherwise it is greedy of GPSR. By performing the function corresponding to the forwarding (greedy forwarding), the neighboring node v closest to the destination is selected as the next node, and the next node for the shortest distance routing is selected. That is, | L (v) -L (b) | for any neighboring node q of the current node u | The node v with = min {| L (q) -L (b) |} is obtained (S117) (where min {x} is a symbol representing the smallest value of x). If the selected v is v ∈ AZ (z) for a dormant source z, it enters a perimeter mode to select next-hop nodes again (S119). Otherwise it forwards the message M to the selected v. The implementation of greedy mode can reduce the number of hops that make up the path, thereby reducing the delay in message delivery.

로 나타내면 u에 이웃한 노드로서 어떠한 휴면 소오스 z에 대해 v

AZ(z)이면서

로부터 반 시계방향이나 시계방향으로 가장 가까운 v를 다음 홉 노드들 선정하고 메시지 M을 전송한다(S119 ~ S123). 일반적으로 휴면 소오스 노드들의 수가 많을수록 우회하여야 할 경계 지역도 늘어나고 경로 길이도 증가한다.In this way, if v selected in the greedy mode or the random mode exists in the boundary area AZ set by the dormant source v (S111, S119), the mode is switched to the parameter mode. In Perimeter mode, the right-hand rule selects the next closest node in the counter-clockwise direction that does not belong to any boundary region based on a straight line from the current node u to the destination b. Alternatively, the next node is selected by applying a left-hand rule that selects the node that is closest in the clockwise direction without belonging to any boundary region as the next node. In other words, the virtual straight line segment from the current node u to the base station b

Denotes v for any dormant source z as a node neighboring u

AZ (z)

Select the next hop nodes v nearest the counterclockwise or clockwise from and transmits the message M (S119 to S123). In general, as the number of dormant source nodes increases, the boundary area to be bypassed increases and the path length increases.

If summarized for TTL _rw of the arrived message M TTL _rw> If 0, but considering the perimeter mode after considering the random mode, first, TTL _rw = 0, then draw Considering D mode with priority, a random mode or a subsequently Perimeter mode is considered.

On the other hand, if it is impossible to select a message delivery node in these three modes, M is returned to the node t which previously sent the message M, which is called a retreat mode (S125). Retreat mode is the process of returning from the current node to the previous node because no further path deployment is possible. Once back, the next-hop node is newly selected by applying the same method as shown in FIG. 3 to the remaining neighboring nodes except the neighboring node visited earlier.

Probability also selected from a greedy mode in the third method p _g, the probability to be selected by perimeter mode p _p, probability of being selected for in the random mode, p _p, and retreat mode is for the probability p _r be performed p _g + p _p + p _{rw -c} + p _r = 1. Here, p _{rw -c} is different from the probability p _{rw -s} of entering random mode. At this time, p _{rw -s} is a value that can be fixed in the protocol in advance, but the values of the remaining variables p _{rw -c} , p _g, and p _p are determined by the number N _s of dormant nodes in the network and their distribution type. It cannot always be fixed.

The path setting according to the present invention is compared with the path setting in the existing representative related studies as follows. It is similar to LPR in that random mode is performed probabilistic every time a message delivery node is selected. However, the difference is that once the random mode continues, it lasts as long as TTL _rw . Therefore, in the proposed protocol, the probability p _rw-s for random mode is not as high as in LPR (for example, in GSLP-w, p _{rw -s} = 0.05 is considered and the maximum is p _{rw -s} = 0.2). In addition, the PR-SP is divided into a random mode moving by an arbitrary length and a routing process that performs greedy transmission, so that the random mode is continuously performed only in the first half. However, the proposed GSLP-w selects the message delivery node each time using the method of FIG. 3 without such a strict classification. The greedy transmission function is basically required for the destination node and is accepted by all existing studies. The most prominent feature of the proposed GSLP-w is the introduction of the concept of dormant sources into source location protection routing. In addition, the active source is in the function of bypassing the area where these dormant sources exist while sending a message to the destination node, i. In the original location-based routing protocol GPSR, it is considered to escape when the next-hop nodes cannot be selected based on a certain criterion, and is applied for location protection of a dormant source. Unlike the previous researches which limited the transmission message per path to one, we try to increase the location protection level but reduce the propagation delay by limiting the random number to w.

The message format transmitted by the activity source in the present invention GSLP-w is shown in Figure 4a. Destination_Coordinate represents the coordinate of the destination node, and Source_Coordinate represents the coordinate of the activity source node. The TTL _rw field indicates the number of hops to continue in random mode. The set value is decreased by 1 every time the node is selected, and when it is 0, it returns to greedy mode. Detour_Rule represents a left hand rule (0) or a right hand rule (1) to set the next node in the parameter mode. The rules are alternately designated by the activity source and the rules apply equally to the destination. These two rules are applied evenly so that the detour path is set to one side without bias.

The More field indicates whether there are any messages left to be delivered along the same path. That is, follow (1) if there is a subsequent message and last (0) for the last message.

On the other hand, in the present invention GSLP-w, w messages per path are continuously delivered. In case of a message that sets a path first, the value of the More field is first (2), and all nodes on the path have their preceding and subsequent nodes. The node must be stored in the routing table. The routing table maintained at the node on the path for delivery of messages using the same path is shown in FIG. 4B. When the value of the More field is first (2), the table is populated by selecting the next hop node. In the table, there are source and destination items representing source and destination nodes, respectively. The node that delivered the message to the current node is stored as previous_hop_node, and the selected message delivery node is stored in next_hop_node. previous_hop_node is used to return the forwarding message to the previous node by backtracking in retreat mode. The routing table is deleted after sending the last (0) message. On the other hand, the interval of messages sent by the activity source assumes a low-duty model that is longer than the time the transmitted message arrives at its destination, so each node does not need to maintain more than one path information. Of the remaining fields, Send_Sequence_Number represents the sequence number of the transmission message, Size_of_User_Data represents the usage information length, and User_Data represents the user information to be transmitted.

5A and 5B show the execution procedure at the active node of the GSLP-w described and the execution procedure at the intermediate delivery node. Here, to refer to a specific field f in the message M, it has the form Mf. For local variables used by the activity source s, the sender of the message, we use _s as a subscript, such as User_Data _s . Detour_Rule _s indicates the bypass rule to be applied in parameter mode. The initial value is assumed to be left-hand (0), and then alternately in the order of right-hand (1) rule, etc. Detour_Rule _s Represented by. 5a is an execution procedure of the active source s, and the number of transmitted messages per path, that is, crew size, is assumed to be arbitrary w. 5b is a procedure performed at an intermediate node that receives the delivery message M.

In the implementation procedure of GSLP-w, by activity source s, TTLrw is an integer c (> 0) predetermined as an initial value, that is, M.TTLrw = c. When the intermediate node receives a message indicating M.Mode == 2, that is, greedy mode, the value of M.TTL _rw is examined. If TTLrw> 0, the next-hop node v is selected in random mode. If there is no node that satisfies the selection condition, M.TTL _rw = 0 is set and the parameter is transferred to the parameter mode to set the message forwarding node again. . So random mode, once started up to the maximum TTL _rw It can be applied continuously as hops. The more dormant sources in the network, the larger the border area, so even if the value of TTL _rw or p _rw-s is increased, the effect of switching to the parameter mode becomes more frequent.

FIG. 6 is an example illustrating the selection process and the message delivery process of the message delivery node of the GSLP-w proposed in FIGS. 3 and 5A / 5B (assuming w = 1 for convenience). Soldiers were assumed for protection. There was one dormant source for each protected object, and each boundary area was established. Neighboring nodes close to base station b, which is the destination in greedy mode from active source s to u ₃ , were selected as next-hop nodes. From u ₃ , since the nodes close to the destination belong to the boundary area, the parameter routing starts. For convenience, the nearest neighbor node u ₄ in the counterclockwise direction by right-hand rule u ₄ And u ₅ are set in turn. From u ₅ to u ₈ , the greedy mode was performed. The random mode starting at u ₈ with TTL _rw = 3 is reduced to greedy mode as TTL _rw = 0 at u ₁₁ , and then reaches destination b. Depending on the relative frequency of application of the three modes of selecting a message forwarding node and the values of parameters such as p _rw-s and TTL _rw , the length and shape of the path between the two nodes can vary greatly.

The length of the route, i.e., the number of hops, through which the message leaving source s by GSLP-w arrives at destination b is determined. For convenience, it is assumed that the node density is high enough that path construction is not possible in any case. The analysis is an intuitive way to find the number of hops in a path that a message originates from an activity source and arrives at the base station.

Compute the length (i.e. number of hops) of the route through which the message sent by the active source s by GSLP-w arrives at destination b. The length is expressed in terms of how many times it is relative to the length of the shortest path between s and b.

A's greedy mode is the probability of performing p _g, the random mode is likely to be performed p _rw-c, probability perimeter mode is performed to select a next hop node, as shown in the sake of convenience FIG. 3 p _p, the final Li Let p _r be the probability that the treatment mode will be performed. However, a p + _rw-c + _g p p _p p + _r = 1, p is a p _{rw rw -c -c} ≤p _rw for the probability p _rw switching to the random mode in the greedy mode in FIG. This is because the switching to the random mode does not all perform the function of the random mode, but when the node in the boundary area is selected, the switching to the perimeter mode is performed again.

The length of the shortest path from active source s to destination b is called d-hop, and represents the number of hops of the shortest path from b to k after moving E (k) from s to k (k> 0). Then at the beginning E (0) = d because it hasn't moved yet. Then, after one-hop shift, E (1) = E (0) -p _g + (1-p _g ) = E (0) + (1-2p _g ). This is because the probability p _g is the shortest distance to b, and the probability (1-p _g ) is the non-shortest distance. That is, E (0) = d, E (1) = E (0) + (1-2p _g ), E (2) = E (1) + (1-2p _g ), ..., E (k The relations with == E (k-1) + (1-2p _g ) d hold. Therefore, in sum, E (k) = d + k (1-2p _g ) is obtained. However, if the destination b is reached after the k-hop movement, E (k) = 0, so d = k (2p _f -1) is established. Then, the number of moving hops that we find, i.e., the length k of the path, is

배의 더 큰 경로를 이용한다. 여기서 2p_g-1>0 즉, 1/2<p_g≤1인 조건을 언제나 만족하여야 전송 메시지가 도착지 b에 도착(수렴)한다. 그렇지 않다면 전송 메시지는 계속해서 네트워크 내의 다른 노드로 발산하여 다음-홉을 선정하는 절차가 반복될 것이다. In other words, GSLP-w is less than the length d of the shortest path.

Use the larger path of the ship. Here, the condition that 2p _g -1> 0, that is, 1/2 <p _g ≤ 1, must be satisfied at all times so that the transmission message arrives (converges) at destination b. Otherwise, the outgoing message will continue to diverge to other nodes in the network and repeat the next hop selection procedure.

For example, if p _g = 0.7, 1 / (2 · 0.7-1) = 1 / 0.4 = 2.5, so the message can be delivered using a path 2.5 times longer than the shortest path. Here, as in the previous studies, if you only want to construct long paths to increase safety periods, you can set the p _g value as close to 1/2 as possible. Alternatively, one may determine how many times longer the path is than the shortest distance and select a p _g value for this. However, it is not a good idea to reduce the value of p _g too small to alleviate the problem of excessive delay due to the longer path length, and also to increase the path length naturally by bypassing the protection targets encountered during message delivery. In addition, these values can be applied as set when there is only one protection target. However, when there are multiple protection targets, there are many boundary regions, so that the parameter routing is frequently performed according to them, thereby reducing the influence of the set values.

Obviously, a node selected in greedy mode always shortens the number of hops to its destination. P _{rw -s} or TTL _rw are configurable values, but p _{rw -c} and p _p are values that vary depending on the number of dormant sources N _s in the network, their distribution patterns, and the size of the boundary region variable β.

The results of the simulation performed to evaluate the source position protection level and performance of GSLP-w are described. First, the assumptions and main parameters for the simulation are explained.

There is no publicly available simulation tool yet available for evaluating the level of security and performance associated with source location protection routing. For the present invention, like other studies, the simulation tool was produced by itself, and the simulation S / W written in Java is about 5,400 lines and the file size is about 541 Kbytes. The functionality is limited to the implementation of the source location protection routing algorithms PR-SP and GSLP-w without including the physical layer or the medium-access control (MAC) layer. The generated traffic in the network assumes a low-duty cycle model, similar to the similar studies, so that the next message occurs after the message from s arrives at base station b. And it is assumed that there is only one active source during the simulation and the protected objects do not move, so that the source nodes do not change. The measurement items were the NSP and NDL of the activity source. As with other studies, the starting position of the tracer was set to the base station for each measurement.

The network considered the case where 50,000 nodes of average order 8 were distributed evenly. The dormant sources were randomly distributed evenly within the network, but for convenience they were experimented with not present within 6r from the active source and the base station (r is the signal reach). The simulation result is the average of 80 topologies except for the highest 10 and the minimum 10 of the values obtained after 100 topologies are simulated. The main parameters and setting values used are shown in FIG. However, when the number of dormant sources N _s is 1% or more of N, the PR-SP without a function of bypassing the boundary area was almost impossible to set. In addition, the case where N _s is 1% or less was first considered on the assumption that N _{s &lt;} N without losing generality. Thereafter, 1.0% ≤ N _s for evaluation in the presence of more dormant sources only for GSLP-w with the ability to bypass the border area. The range was expanded to ≦ 2.5%.

The source location protection routing scheme was evaluated using the safety period and delivery latency introduced in the previous study. The safety period is the number of messages sent by a source node (i.e., an active source) that sends a message to a base station before its location is exposed to the attacker. In other words, the safety period is a factor that compares the relative security levels between routing schemes. The propagation delay, which is a performance-related measure, is defined as the average number of hops in the path used to transmit messages for the safety period. Ideal routing schemes should provide long safety periods and low propagation delays.

In the PR compared to the GSLP-w proposed in the present invention, since all of the PRs use a single path rather than a deception message or a multipath, the average propagation delay for each path is the same as the average number of generated messages per path. It is not evaluated separately. In addition, not only the activity source transmitting the message but also the nodes neighboring to the target requiring location protection although the message is not being transmitted, the safety period is redefined as modified as follows.

Modified safety period: The total number of messages sent to the base station before the active source is exposed to the attacker without the location of any node (i.e., dormant source) in close proximity to the protected object that needs location protection.

Previous studies have shown that longer distances between the active source and the base station result in higher safety periods and longer propagation delays, while closer ones result in lower safety periods and shorter propagation delays. In addition, in evaluating the safety period and propagation delay, the base station is assumed as the initial tracking position of the tracker. Therefore, in the present invention, the normalized safety period (NSP) obtained by dividing the safety period and the propagation delay by the relative safety period and the propagation delay for the shortest hop number between the active source and the base station, that is, the shortest hop number between the active source and the base station, Use normalized delivery latency (NDL). This allows for relative quantification of how many safety periods and how many propagation delays compared to shortest distance routing.

8 shows the trajectories of the paths set by GSLP-w when the dormant source node number N _s is 0.4% of the total node number N. FIG. The dormant sources are distributed evenly over the network, assuming that one message is delivered per path, that is, w = 1. In order to avoid complexity, normal nodes are not shown, only dormant sources, base stations and active source nodes are shown as dots. Each dormant source is surrounded by two circles: the inner circle is the exposed area with α = r and the outer circle is the border area with β = 2r. The attacker's location tracking was initiated from the base station at the bottom left, and the tracking path was shown on each hop by bold circles with radius r. The route taken by the message from the activity source (located in the large circle in the upper right) is shown by a thin solid line. Eventually, the location of the active source was halted or terminated, but all dormant sources were protected by the ability to bypass the border area.

The shortest hop number h _{s -b} between the base station and the active source was 50, and the probability of performing random mode was p _{rw -s} = 0.05. Therefore, h _{s -b} ?? p _{rw -s} = 50 ?? 0.05 = 2.5 nodes entered random mode, and after entry, 5% to 10% of h _sb , that is, the range of TTL _rw ∈ [3, 5] It can be said that the random mode continued as much as the hop belonging to. The normal safety period was NSP = 4.38, which means that the active source s sent (on average) h _{s -b} ?? NSP = 50 ?? 4.38 = 219 messages to base station b before the attacker was discovered. In other words, the message was sent 4.38 times the shortest hop number with the base station, and the number of paths used was = 1 since w = 1. Since the normal propagation delay NDL = 1.50, the average number of hops in the path used is 1.5 times the shortest hop number with the base station, that is, h _{s -b ·} NDL = 50 · 1.50 = 75.0.

The paths are almost evenly set from side to side based on a virtual straight line connecting the activity source and the base station. This is because the rule of the parameter routing specified by the activity source, that is, the left-hand rule and the right-hand rule are alternately specified. If the tracer is attracted to either side, messages sent to the other side will be secure. In addition, as the number of messages delivered through this secure path increases, the safety period may increase. Of course, in any case, the abundance of available routes will make these points stand out. Under this hypothesis, we consider the proposed number of transmission messages w as follows. However, h _{s -b} is set as h _{s -b} = | L (s) -L (b) | / r as the shortest hop number between the active source s and the base station b.

w = 1: send one message as in other existing studies

w∈1Q: randomly selected in the range [1, hs _-b / 4] corresponding to the first quarter of h _{s -b} to consider the case where the number of transmitted messages per path is relatively small

w∈2Q: randomly selected in the range [(h _{s -b} / 4) +1, hs _-b / 2]

w∈3Q: randomly selected in the range [(h _{s -b} / 2) +1, (3h _{s -b} ) / 4]

w∈4Q: Randomly selected in the range [((3h _{s -b} ) / 4) +1, h _sb ] to account for the relatively large number of message transmissions per path

w∈2 / 3Q: to consider when selecting, based on the middle of _{h s -b [(h s -b} / 4) +1, (3h sb) / 4] randomly selected in the range of

First, the location protection level and the propagation delay characteristics were investigated as the number of transmission messages w per path and the number N _s of dormant sources increased. Simulation results are compared with PR-SP, the most representative method of source location protection routing. Here, the PR-SP is a case of using a single path by the shortest path algorithm in the process of delivering to the base station which is the final destination, which is the routing step of the PR.

The measured NSPs are shown in FIGS. 9A-9C. In general, since PR-SP does not have the ability to bypass the dormant source (exposure area), the number of messages sent (ie, NSP) increases rapidly due to the exposure of the dormant source during message delivery with increasing N _s . It tended to shrink. Here, the safety period in the case of the dormant source is defined as "the total number of messages transmitted to the base station before the active source is exposed to the attacker without any location of the dormant source detected". In the case of PR-SP, as h _{s -b} becomes longer, it has to pass through a larger number of boundary regions, so as the h _{s -b} increases, the NSP decreases faster. For example, in Figures 9A, 9B and 9C, as N _s increased from 0.0% to 0.4%, the drop in NSP increased to about 1.3, 2.2 and 3.8. On the other hand, the proposed GSLP-w has a function of bypassing the boundary area including the exposed area by the perimeter routing function, so that the level is maintained without significant change even if N _s increases. Some showed a local increase with increasing N _s . This is because as the density of dormant sources increases, the frequency of bypassing the exposed areas increases and thus the length of the message delivery path increases.

Note that in the case where the distance between the active source and the base station is relatively short (FIG. 9A), the NSP of the PR-SP was higher than the proposed GSLP-w as a whole. This is one reason that the parameter p _{rw -s} = 0.05 used in the random mode given in FIG. 7 is set low. In addition, since the parameter TTL _rw is selected in the range of 5% to 10% of h _{s -b} from 2 (minimum value), that is, in the case of h _{s -b} = 30, only TTL _rw ∈ [2, 3]. This is why they are not set. Therefore, higher NSP can be obtained by increasing p _{rw -s} or TTL _rw , which will be described later.

GSLP-w is proportional to the distance between h _s h _{s -b} longer the _-b and exhibited the higher the density of the N _s higher NSP (Fig. 9b and 9c). In particular, when Ns> 0.4% and h _{s −b} ≧ 50, GSLP-w showed higher NSP than PR-SP. In the case where h _{s -b} = 70 (FIG. 9C), the N- _s became less than or equal to 1.0 when N _s passed 0.6%. This is because the location of the dormant source was detected early in the tracking process and the location was terminated early while the number of messages sent from the active source sent fewer messages than the shortest hop number h _sb between the active source and the base station.

Among the various w values of GSLP-w, if the number of messages in the range 1Q corresponding to the first quarter of h _{s -b} , that is, the number selected from [1, h _{s -b} / 4] is sent. Gave the highest NSP. As the selection range increased to 1Q, 2Q, 3Q, and 4Q, the NSP decreased for the same N _s . In the case of 2 / 3Q, it was generally within the range of 2Q and 3Q. Overall, w was in the upper group in the range of 1Q and 2Q, 2 / 3Q was in the middle, and 3Q and 4Q were in the lower group. And, as in previous studies, when one message is transmitted per path, it is medium or slightly higher. In particular, as N _s increases, the difference between w ∈ 1Q and w ∈ 4Q increases. It is interpreted that w ∈ 4Q is the lowest as the length of the configuration path increases as N _s increases but the number of paths used decreases and the number of nodes overlapped between paths increases.

In conclusion, in large networks where dormant sources exist, sending a relatively small number of messages per path provides a higher safety period than sending a single message or a large number of messages.

The measured average path lengths of the paths provided with the NSPs of FIGS. 9A-9C, that is, the normal propagation delay NDL, are as shown in FIGS. 10A-10C. Since the PR-SP sets the path regardless of the exposed area or boundary area, that is, without detour, the PR-SP shows a nearly constant normal propagation delay NDL regardless of the increase of N _s . On the other hand, the proposed GSLP-w increased the NSP as the length of the path increased with the increase of N _s and thus the NDL. However, the mutual difference for different w values remained within about 0.2 even though the increase of N _s was not as large as the difference between NSPs of FIGS. 9A to 9C. Even when the NDL of GSLP-w was the largest (FIG. 10C), it did not exceed 0.5 when compared with PR-SP. The maximum value of NDL occurred when h _sb and N _s were the maximum as shown in FIG. 10C. The maximum delay was 1.85 with an average of 1.53.

In FIG. 10B and FIG. 10C, the perimeter mode is frequently performed due to an increase in the boundary area according to the increase of N _s , and some retreat modes occur to increase the path length, thereby increasing the NDL. Interestingly, even though GSLP-w showed a higher NSP than PR-SP, there was a case where the NDL was lower. As can be seen by comparing FIG. 9B with FIG. 10B, the neighborhood where N _s = 0.4 corresponds to h _{s −b} = 50. In addition, when h _{s −b} = 70, a higher safety period was provided with lower propagation delays in the range where N _s was about 0.05% <N _s <0.4%.

Therefore, it was confirmed that a routing strategy for transmitting more messages over shorter length paths is possible by avoiding the one-sided preference for long paths or adherence to the transmission of a single message per path.

In summary, GSLP-w, which has the ability to bypass the boundary regions where dormant sources exist, provided a higher normal safety period NSP than N PR with an increasing N _s and longer h _{s -b} . GSLP-w was the best when considering the increased safety period compared to the increase in propagation delay.

Simulated for a safe period of time and the transfer delay of the proposed GSLP-w when the number of dormant source N _s high results are shown in Figure 11a and Figure 11b. Here, only GSLP-1 with w = 1 is shown for comparison with GSLP-1Q, w1Q which gave the highest NSP at 1.0% ≦ N _s ≦ 2.5%. If N _s is more than 2.5%, there are few configurable paths or the number is so small that no further simulations have been performed. For reference, the results for other w values shown in FIGS. 10A to 10C showed lower NSPs than GSLP-1Q, and were omitted to avoid complexity of the figure. The parenthesis of the data label indicates the number of hops by putting the value of the hop number h _sb between the active source and the base station.

First, referring to FIG. 11A, GSLP-1Q provided a higher NSP under the same conditions than GSLP-1. The difference was larger as h _{s -b} increased. In comparison with FIG. 9 which shows NSP when N _s = 0,0%, 0.4%, and 0.8%, N _s = 1.5% was the greatest when h _{s -b} = 30 and h _{s -b} = 50. , h _{s -b} = 70 was the highest when N _s = 1.0%. After that, as shown in Figure 11a with increasing N _s decreased. This decrease is due to the increase of N _s and go beyond a certain level plunged number of configurable paths lowered the safety period. 11b shows the propagation delay, with GSLP-1 having a lower NSP longer. From h _{s -b} ≥50 and N _s ≥2.0%, the propagation delay exceeded about 3.0 times the maximum number of hops between the active source and the base station and increased up to 4.0 times. This means that the perimeter mode becomes more frequent and the path length becomes very large.

In conclusion, even at very high N _s , GSLP-1Q provided a higher safety period NSP with lower propagation delay NDL than GSLP-1.

In the random mode of GSLP-w, two parameters are given so that various nodes configure different paths. One is the probability of executing random mode with p _{rw -s} , and the other is the number of hops TTL _rw to apply random mode continuously. Also be relatively low, as shown by putting p = 0.05 _{rw -s} to 7, TTL _rw also h _{s -b} is selected from the range of 5 ~ 10% h _{s -b} = 30 days when nothing more than just two or three. This is because the GSLP-w proposed in the present invention was originally intended for source location protection routing considering a dormant source in a wireless sensor network composed of many thousands to tens of thousands or more nodes. This is because, when h _sb is relatively long and the parameter routing is performed due to dormant sources, the length of the set path is increased, which may indirectly produce a similar effect to that of the random mode (see FIG. 9C). Nevertheless, we have simulated how source level protection and performance of GSLP-w can be improved by increasing p _{rw -s} and TTL _rw in environments with relatively short h _sb or low density of dormant source nodes. The discussion only considers GSLP-1Q, the best-performing NSP among GSLP-w, and the PR-SP to be compared.

9a to 9c, the case where GSLP-w had the lowest NSP was considered h _{s -b} = 30. The conclusion was that increasing TTL _rw was more effective than increasing p _{rw -s} . The initial TTL _rw of FIG. 7 was increased by 1 times (= ㅧ 1), 2 times (= ㅧ 2), 3 times (= ㅧ 3) and 4 times (= ㅧ 4). That is, TTL _rw was randomly selected and used in the range of [2, 3], [4, 6], [6, 9], and [8, 12], respectively, and the NSP of GSLP-w was shown in FIGS. 12A and 12B. Same as Overall, the NSP increased in proportion to the increase in TTL _rw , but declined most since N _s = 0.4%. The effect of increasing TTL _rw was generally the highest at N _s = 0.4%. The reason why the effect of increasing TTL _rw decreases at a certain level with increasing N _s is analyzed as follows. In other words, as N _s increases, the boundary area increases, which causes frequent transition to perimeter mode during the message forwarding node selection process, so that the effect of increasing TTL _rw no longer persists. On the other hand, with increasing N _s , the NSP of the PR-SP rapidly decreased, and when N _s ≥0.4%, GSLP-1Q showed a higher safety period even by doubling the TTL _rw .

Meanwhile, as shown in FIG. 12, when h _{s -b} = 30, p _{rw -s} = 0.05 is replaced by 1 times (= 0.05), 2 times (= 0.1), 3 times (= 0.15), and 4 times (= 0.2) instead of TTL _rw . In the case of increasing to, the results were as follows (Figures are not provided in this description).

In the case of N _s = 0.0%, all NSPs of GSLP-1Q increased in proportion to the increase in p _rw-s but did not exceed PR-SP. However, as N _s increased, the NSP of the PR-SP was relatively lower, resulting in a higher NSP than the PR-SP. Overall, it was slightly lower than the highest value of 5.21 (Fig. 12A) when the TTL _rw was increased not to exceed 3.5.

Simulations were also performed for NSPs and NDLs with increasing TTL _rw for GSLP-1Q at h _{s -b} = 50 and 70 for medium and large networks (figure not shown in this description).

Increasing the TTL _rw of GSLP-1Q by more than 2 times at h _{s -b} = 50 all gave a higher NSP than PR-SP. In the case of h _{s -b} = 70, the NSP was higher than the PR-SP in all cases except that the TTL _rw did not increase when the N _s was about 0.2% or less, that is, x1. A four-fold increase in TTL _rw doubled the NSP of the PR-SP. As N _s increases, the path length increases due to partial retreat during the simulation, and more than twice the length of h _sb occurs. For example, with h _sb = 70, the mean NDL for quadrupled TTL _rw of GSLP-1Q was 2.03, with a minimum of 1.76 at N _s = 0.0% and a maximum of 2.29 at N _s = 0.8%.

In _conclusion , increasing the number of applied hops TTL _rw in random mode was more effective in increasing the safety period, rather than increasing the probability p _{rw -s} . This is because the increase in TTL _rw is greater in the path length and the path building effect by the various nodes.

In the present invention, GSLP-w is proposed as a routing scheme for reducing message propagation delay while enhancing source location confidentiality in a large sensor network in which dormant sources exist. The proposed routing considers the more general case of protecting not only the active source transmitting the message but also the location of dormant source nodes in proximity to the targets requiring location protection. The selection of the message forwarding node is determined by the greedy mode and the random mode with a certain probability, and when a node within the boundary area requiring location protection is selected, it is bypassed to the alternate node by the parameter routing. The number of transmitted messages per path was not limited to one but expanded to w. This allowed us to reduce the length of the path as a whole while increasing the safety period. The highest source location confidentiality was provided when w was randomly chosen in the range of the first quarter of the shortest hop number between the sender and destination of the message. In addition, it has been shown that increasing the application probability and the application hop number of the random mode in the message delivery mode can provide an improved safety period. And the message propagation delay stayed mostly within twice the shortest hop count between the source and destination nodes.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a diagram illustrating a network environment for explaining a dormant source concept in the present invention.

2 is a conceptual diagram illustrating boundary area and exposure area setting by source nodes;

3 is a flow chart illustrating a routing method for enhancing source location confidentiality in a sensor network in accordance with the present invention.

Figure 4a is the format of the transmission message, Figure 4b shows a routing table.

FIG. 5A illustrates a procedure of performing an activity source, and FIG. 5B illustrates a procedure of performing an intermediate node.

6 is a diagram illustrating routing of GSLP_w according to the present invention;

7 is a table showing setting values of main parameters applied to the present invention.

8 is an exemplary diagram of paths established by GSLP_w.

9A-9C show changes in normal safety period (NSP) as the number of human sources increases.

10A-10C are diagrams of the change in normal propagation delay (NDL) with increasing human sources.

11A and 11B show changes in NSP and NDL according to GSLP-1Q when the number of human sources is large.

12A and 12B are diagrams illustrating changes in NSP and NDL with increasing TTLrw.

Claims (10)

A routing method for enhancing source location confidentiality in a wireless sensor network including a source node (active source), a human source, and a base station, A first step of performing a greedy transmission technique for routing the shortest distance in the source node and a random routing technique for randomly deploying a path for a predetermined hop; And And a second process of protecting the position of the dormant source from chasing by a tracer when the base station approaches the place where dormant sources exist while performing the first step. Routing method that enforces source location confidentiality in the network. The method of claim 1, wherein the first process comprises: Receiving a message from a neighbor node at a current node, searching for a field (TTLrw) indicating whether or not to continuously perform a random mode of randomly deploying a path for a predetermined hop in a transmission message format; A second step of continuously performing a random mode by the hop if there is a hop capable of performing a random mode as a result of the search; Generating a variable to enter a random mode for a given probability (Prw-s) when there is no hop capable of performing the random mode as a result of the search; When the generated variable is less than or equal to the given probability (Prw-s), reentry the random mode, and when the generated variable is larger than the given probability (Prw-s), the greedy mode performs greedy forwarding. And a fourth step of entering into the wireless sensor network. The method of claim 2, wherein the first process comprises: In the case of entering the greedy mode, the neighboring node that is closest to the destination is selected as the next node, and the shortest distance routing is performed. In case of the random mode, the neighboring node that does not increase the distance of the arrival path is selected. Routing method for enhancing source location confidentiality in a wireless sensor network, the method comprising increasing randomness. The method of claim 1, wherein the second process comprises: Set a boundary area to protect the position of the dormant source, and if it approaches the dormant source set in the boundary area during routing, perform the perimeter mode to bypass the boundary area, but the clock is based on a straight line from the current node to the destination. And transmitting a message by selecting a node that exists closest in the opposite or clockwise direction as a next node, and transmitting a message. The method of claim 1, further comprising a third step of returning a message from a current node to a previous node by entering a retreat mode when the path deployment is impossible after the second step. Routing method for increased confidentiality. The method of claim 3, wherein the first process comprises: When the message is returned, the previous node enters grid mode and newly selects the next hop node for the remaining neighboring nodes except for the previously visited neighboring node. The method of claim 2, wherein the transmission message format, A Destination_Coordinate field indicating the coordinate of the destination node; A Source_Coordinate field indicating the coordinate of the activity source node; A Mode field describing a method of selecting a message forwarding node; A TTLrw field indicating the number of hops to continue in the random mode; A Detour_Rule field indicating a left-hand rule (0) or right-hand rule (1) for setting the next node in the parameter mode; A More field indicating whether there is still a message to be delivered along the same path; Send_Sequence_Number field indicating the sequence number of the transmission message; A Size_of_User_Data field indicating a length of usage information; Routing method for enhancing source location confidentiality in a wireless sensor network comprising a User_Data field indicating the user information to be transmitted. The method of claim 1, wherein the boundary area considers node density in the network, but when the node density is low, increasing the radius including the exposed area having a predetermined radius around the protected object to block the inflow of the message into the exposed area. A routing method for enhancing source location confidentiality in a wireless sensor network. The method of claim 1, wherein the shortest distance routing is applied to calculate a hop number that is k times longer by the following formula than the hop number d passing through an active source message until it reaches its destination. Routing method for enhancing source location confidentiality in wireless sensor networks. <Formula>

(0 <Pg <1/2) Here, Pg represents the probability that the greedy mode is performed. The number of hops between the base station and the base station of claim 1, wherein w is the message sender, including sending a single message per path, when sending w messages per path.

Corresponds to the first quarter of

A routing method for strengthening source location confidentiality in a wireless sensor network, characterized in that the highest security level is achieved by sending a randomly selected message in a range.

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