Ad-hoc covert communication system and method using chaos signal

Abstract

The present invention relates to an ad-hoc stealth communication system and method using chaotic signals. It generates a transmission frame comprising a preamble that performs narrowband high-speed frequency hopping and a payload spread into chaotic signals. It transmits synchronization information and control information for synchronization between a transmitting side and a receiving side through the preamble, and generates the same chaotic sequence based on the control information to transmit and receive the payload. According to the present invention, secure communication with high anti-jamming and low detectability performance is possible, and rapid ad-hoc network configuration is possible without prior infrastructure.

Description

Technology Field

[0001] The present invention relates to a communication system, and more specifically, to an ad-hoc communication system and method that combines chaotic signals and high-speed frequency hopping to improve stealth and anti-jamming performance and enables rapid network configuration without prior infrastructure. Background Technology

[0002] Communication systems for emergency deployment missions must be robust against signal eavesdropping and jamming, and require ad-hoc communication technology that can be rapidly deployed and used without prior infrastructure.

[0003] Conventional frequency hopping communication performs communication by rapidly changing frequencies, so it has anti-jamming performance, but synchronization is required to precisely change frequencies at the same time between the transmitter and receiver. In addition, efficiency is reduced due to frequency changes such as mute time during frequency hopping, and there is a problem that it is difficult to conceal due to high signal strength compared to direct spread communication.

[0004] Meanwhile, conventional chaotic communication is a signal that is non-periodic, unpredictable, random, and hidden, making it suitable for secure communication and enabling multiple access via spreading codes, but it has the disadvantage that the transmitting and receiving sides must achieve precise time synchronization. In particular, due to synchronization issues with the chaotic signals at the transmitting and receiving sides, conventional technology has the problem of being difficult to use in environments where network synchronization is not fixed or transmission delay is not guaranteed through satellite relay. The problem to be solved

[0005] The present invention has been devised to solve the above-mentioned problems and aims to provide a communication system having high anti-jamming and low detectability performance by combining high-speed frequency hopping and chaotic signal spreading.

[0006] In addition, the purpose is to provide a communication system that enables the transmission and reception of chaotic signals without a prior synchronization procedure within the network prior to operation, and allows relaying without a packet exchange procedure to configure the network, thereby enabling the rapid configuration and operation of an ad-hoc network after mission deployment. means of solving the problem

[0007] An ad-hoc hidden communication method using a chaotic signal according to an embodiment of the present invention for achieving the above-mentioned purpose comprises: a transmitter that generates a chaotic signal having non-periodicity and non-predictability, manages operational information, and generates a transmission frame; a relay unit that determines whether to relay a signal received from the transmitter and performs relaying using a TDMA method; and a receiver that processes the received signal, analyzes the frame, and despreads the chaotic signal; wherein the transmitter comprises: an operational information management unit that manages broadcasting, one-to-one, and one-to-many communication services; a transmission frame generation unit that generates a transmission frame including a preamble that performs narrowband high-speed frequency hopping and a payload spread into a chaotic signal; and a transmission signal generation unit that generates a transmission signal.

[0008] And, the relay unit is characterized by including: a relay condition determination unit that determines whether to relay a received signal; a TDMA relay unit that performs relaying using a TDMA (Time Divisional Multiple Access) method; and a relay frame generation unit that generates a relay frame.

[0009] In addition, the receiver is characterized by including: a received signal processing unit that processes the received signal; a received frame analysis unit that analyzes the received frame; and a chaos signal despreading unit that despreads the chaos signal.

[0010] In addition, the relay condition determination unit is characterized by including: a signal quality measurement unit for measuring signal quality; a packet sequence number verification unit for verifying packet sequence number; and a node ID verification unit for verifying node ID.

[0011] In addition, the TDMA relay unit is characterized by including a time slot allocation unit that allocates a time slot; and a relay signal generation unit that generates a relay signal.

[0012] In addition, the relay frame generation unit is characterized by including a chaos sequence transformation unit that generates different chaos sequences for each relay node and redeploys the payload.

[0013] In addition, the received signal processing unit is characterized by including a frequency control unit that controls the frequency; a frame synchronization unit that performs frame synchronization; and a hopping pattern generation unit that generates a hopping pattern.

[0014] In addition, the above-mentioned receiving frame analysis unit is characterized by including a control information analysis unit that analyzes control information; and a synchronization information analysis unit that analyzes synchronization information.

[0015] In addition, the chaos signal dediffusion unit is characterized by including a chaos sequence restoration unit that restores a chaos sequence; and a data restoration unit that restores data.

[0016] An ad-hoc hidden communication method using a chaotic signal according to an embodiment of the present invention for achieving the above-mentioned purpose comprises: a step in which a transmitter generates a chaotic signal having non-periodicity and unpredictability; a step in which the transmitter sets a transmission frame structure; a step in which the transmitter generates a preamble; a step in which the transmitter band-spreads a payload; a step in which the transmitter determines whether to transmit or relay; a step in which, if the transmitter transmits, the transmitter transmits the preamble and transmits the payload; a step in which, if the relay is relayed, the relay unit checks relay conditions and determines whether relay conditions are satisfied, and performs TDMA (Time Divisional Multiple Access) based relay; a step in which a receiver generates a chaotic sequence; and a step in which the receiver despreads the payload.

[0017] And, the transmission frame structure is characterized by including: an Fc section that includes a sequence for frame synchronization, a node number, and a packet number and is transmitted over a common frequency for synchronization within the network; an Fn section that includes chaotic sequence information and data length information of the payload and is transmitted over a frequency for transmitting node-specific control information; and an Fp section in which a payload that has been band-spread with a chaotic signal is transmitted.

[0018] In addition, the step of checking the relay conditions comprises at least one of: a step of checking whether the sender or receiver of the received signal is its own node ID; a step of checking whether the quality of the received signal is above a preset threshold; and a step of checking whether the sequence number of the received packet is below a relay limit value.

[0019] And, the step of performing the above TDMA-based relay is characterized by multiple relay nodes sequentially transmitting relay frames according to their respective allocated time slots, while increasing the packet sequence number during relay and transmitting. Effects of the invention

[0020] According to the present invention, the following effects can be obtained:

[0021] First, by combining high-speed frequency hopping and chaotic signal spreading, secure communication with high anti-jamming and low detectability performance is possible.

[0022] Second, since the transmission and reception of chaos spread signals are possible without a prior synchronization procedure within the operational network, rapid network configuration is possible even in situations such as emergency deployment missions.

[0023] Third, since relaying is possible without the packet exchange procedure required to configure the network, an ad-hoc network can be quickly configured and operated after mission deployment.

[0024] Fourth, since there is no need to designate relay nodes and thus no need to manage routing tables, implementation is simple, and since there is no need to exchange packets for topology updates, signal exposure in the time axis can be suppressed.

[0025] Fifth, since multiple relay nodes can be selected by utilizing the correlation characteristics of chaotic signals, broadcast propagation throughout the entire network is facilitated.

[0026] Sixth, by using chaotic signals, efficiency is increased compared to using the full frequency hopping method, and hidden communication is possible. In particular, the actual data portion is hidden and invisible in the spectrum, except for the initial high-speed hopping signal.

[0027] Seventh, by using a high-speed narrowband frequency hopping preamble, frequency hopping signals can be minimized and anti-jamming performance can be ensured.

[0028] Eighth, relay signals provide security because multiple nodes perform hopping using different frequencies at the same time, making it difficult to separate information by node even when signals are collected for a long time.

[0029] Ninth, rapid signal propagation is possible as each node selected as a relay node transmits simultaneously without interference through direct hopping and spreading.

[0030] Through these effects, the present invention can be effectively utilized in special environments requiring security, such as military communications and emergency deployment missions. Brief explanation of the drawing

[0031] FIG. 1 is a diagram illustrating an operating environment to which the communication system of the present invention is applied. FIG. 2 is a diagram illustrating the network configuration of the communication system of the present invention. FIG. 3 is a diagram illustrating the basic structure of a transmission frame according to the present invention. Figure 4 is a diagram showing the signal distribution on the spectrum of a communication system according to the present invention. Figure 5 is a diagram showing the basic structure of a transmission frame according to the present invention. Figure 6 is a diagram showing the detailed structure of the transmission frame of Node 2. Figure 7 is a diagram showing a transmission frame structure for interference avoidance during simultaneous transmission of multiple nodes in the time-frequency plane. FIG. 8 is a diagram showing an example of a network configuration consisting of five nodes in an ad-hoc communication system of the present invention. Figure 9 is a diagram showing the transmission of Node 2 and the reception of surrounding nodes. Figure 10 is a diagram showing the relay path when Node 2 transmits. Figure 11 is a diagram showing the timing and frame structure of relay transmission. FIG. 12 is a diagram showing in detail the relay packet transmission and reception process (1200). FIG. 13 is a diagram showing an example of operation of the multi-hop broadcasting and telecommunications of the present invention. FIG. 14 is a diagram showing an example of operation of one-to-one and one-to-many communication of the present invention. FIG. 15 is a block diagram showing the overall configuration of the ad-hoc hidden communication system of the present invention and the detailed configuration of each part. FIG. 16 is a block diagram showing the detailed configuration of the transmitting unit (1510) of the present invention. FIG. 17 is a block diagram showing the detailed configuration of the relay unit (1532) of the present invention. FIG. 18 is a block diagram showing the detailed configuration of the receiver (1550) of the present invention. Specific details for implementing the invention

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the attached drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention belongs. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0033] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “have,” “may have,” “include,” or “may include” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. Terms including ordinal numbers, such as “second,” “first,” etc., may be used to describe various components, but said components are not limited by said terms.

[0034] The above terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be named the first component, and similarly, the first component may be named the second component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0035] In this specification, identification symbols (e.g., a, b, c, etc.) for each step are used for convenience of explanation and do not indicate the order of the steps; the steps may occur differently from the specified order unless the context clearly indicates a specific order. That is, the steps may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

[0036] Additionally, the term “part” as used in this specification may refer to software or hardware components such as field-programmable gate arrays (FPGAs) or ASICs, and the “part” performs certain roles. However, the “part” is not limited to software or hardware. The “part” may be configured to reside in an addressable storage medium or configured to run one or more processors. Thus, as an example, the “part” may include components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data structures, and variables. The functions provided within the components and “parts” may be combined into a smaller number of components and “parts” or further separated into additional components and “parts.”

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0038] FIG. 1 is an operational environment diagram to which the communication system of the present invention is applied, showing a situation in which multiple nodes form an ad-hoc network and communicate in an environment where complex terrain features, such as mountainous terrain, exist. Node 1 (105) and Node 2 (110) are located in the first mountainous terrain, and Node 3 (115), Node 4 (120), and Node 5 (125) are located in the second mountainous terrain, and each node communicates with one another through a communication path indicated by a dotted line.

[0039] FIG. 2 is a network configuration diagram of the communication system of the present invention, illustrating the communication relationships between multiple nodes in hop units. Centered on Node 1 (205), Node 2 (210) and Node 3 (215) are located at a distance of 1 hop, and Node 4 (220) and Node 5 (225) are located at a distance of 2 hops through Node 2 (210) and Node 3 (215), respectively. Node 6 (230) is located at a distance of 3 hops through Node 4 (220) and Node 5 (225), respectively. Additionally, Node 4 (220) and Node 5 (225) can also be connected through Node 3 (215) and Node 2 (210), respectively, allowing for the formation of various relay paths. Through this network configuration, multi-hop communication via intermediate nodes is possible even between nodes that cannot communicate directly, and in particular, even if one relay path is disconnected, stable communication can be maintained through another relay path.

[0040] FIG. 3 is a basic structural diagram of a transmission frame according to the present invention, wherein the transmission frame (300) is composed of a preamble section (310) and a payload section (320).

[0041] In the preamble section (310), frequencies from Fs1 to Fs#, which are synchronization frequencies (330), are sequentially assigned, and in the payload section (320), Fp, which is a payload frequency (340), is assigned.

[0042] In the time-frequency plane, in the high-speed frequency hopping section (350), frequencies from Fs1 to Fs# are transmitted while rapidly hopping, and in the subsequent chaotic band-spreading section (360), a payload band-spread by a chaotic signal is transmitted.

[0043] Through this transmission frame structure, anti-jamming performance can be secured through high-speed frequency hopping in the preamble section (310), and low detectability performance can be achieved through spread spectrum using chaotic signals in the payload section (320).

[0044] FIG. 4 is a signal distribution diagram on the spectrum of a communication system according to the present invention, showing the characteristics of a preamble (400) and a payload (410).

[0045] The preamble (400) appears as a peak with high signal strength in the spectrum, which shows the characteristics of a signal performing high-speed frequency hopping. Each peak indicates that the frequencies from Fs1 to Fs# in FIG. 3 are transmitted by hopping sequentially.

[0046] On the other hand, the payload (410) is band-spread by the chaotic signal and distributed at a noise level with low signal strength in the spectrum. This shows that the payload is spread across a wide band by the chaotic signal and is hidden in the spectrum.

[0047] Through these spectral characteristics, it can be seen that the preamble secures anti-jamming performance through high-speed frequency hopping, and the payload achieves low detectability performance through spread spectrum using chaotic signals.

[0048] FIG. 5 is a diagram showing the basic structure of a transmission frame according to the present invention. The transmission frame (500) consists of a preamble section (510) and a payload section (550). The preamble section (510) includes a synchronization information section (511) and a control information section (512). The synchronization information section (511) includes Fc sections (513a, 513b, 513c, 513n), which are common frequencies for synchronization within the network, and the control information section (512) includes Fn sections (514a, 514b, 514c) for transmitting control information per node. The payload section (550) consists of an Fp section (521) in which band-spread data is transmitted as a chaos signal.

[0049] Figure 6 is a diagram showing the detailed structure of the transmission frame of Node 2.

[0050] The transmission frame (600) includes a preamble section and a payload section.

[0051] The preamble section consists of time slots (602, 604, 606, 608, 610) sequentially allocated along the time axis, and among these, time slot (602) is allocated Fc, a common frequency for synchronization within the network, to transmit basic information of Node 2. In this Fc section, synchronization information such as a sequence for frame synchronization, a node number, and a packet number is transmitted.

[0052] In the control information section (620), control information such as the chaotic sequence information and data length information of the payload is transmitted through the five frequencies (Fn1_2, Fn2_2, Fn3_2, Fn4_2, Fn5_2) assigned to Node 2.

[0053] Finally, in the payload section (630), the actual data band-spread with the chaos signal is transmitted via the Fp frequency.

[0054] Through this frame structure, Node 2 can communicate effectively with other nodes in the network while maintaining the stealth of the transmitted data.

[0055] FIG. 7 is a diagram showing a transmission frame structure for interference avoidance during simultaneous transmission of multiple nodes in the time-frequency plane. The transmission frame (705) of each node (710, 720, 730) is divided into time separation (740), frequency separation (750), and low correlation spreading (760) sections.

[0056] The transmission frames of Node 1 (710), Node 2 (720), and Node 3 (730) each include a preamble section (710a, 720a, 730a) and a payload section (710b, 720b, 730b).

[0057] In the time separation interval (740), the Fc (710c, 720c, 730c) of each node is transmitted at different times to avoid interference.

[0058] In the frequency separation section (750), the frequencies assigned to each node (Node 1: Fn1_1 ~ Fn5_1, Node 2: Fn1_2 ~ Fn5_2, Node 3: Fn1_3 ~ Fn5_3) are transmitted while hopping at different frequencies and times to prevent mutual interference.

[0059] In the low-correlation spreading section (760), the payload of each node is band-spread into different chaos sequences and transmitted through the Fp frequency. At this time, interference between simultaneously transmitted signals is minimized due to the low correlation characteristics between the chaos sequences.

[0060] Through this structure, interference that may occur during communication between multiple nodes can be effectively avoided by utilizing time separation, frequency separation, and low correlation characteristics.

[0061] FIG. 8 is a diagram showing an example of a network configuration consisting of five nodes in an ad-hoc communication system of the present invention.

[0062] Node 1 (810), located in the center, is assigned a unique identifier ID of 1 and serves as the central node of the network. Node 2 (820, ID: 2) and Node 3 (830, ID: 3) are located at a 1-hop distance from Node 1 (810) so that they can communicate directly.

[0063] Node 4 (840, ID: 4) is connected to Node 2 (820), and Node 5 (850, ID: 5) is connected to Node 3 (830), and they are located 2 hops away from Node 1 (810). Additionally, Node 4 (840) and Node 5 (850) are directly connected to each other, allowing for communication through various paths.

[0064] In this network configuration, each node has a unique ID, allowing for node identification during transmission and reception, and enables multi-hop communication through intermediate nodes even between nodes that cannot communicate directly. For example, if Node 4 (840) wants to communicate with Node 3 (830), it can choose a path via Node 2 (820) and Node 1 (810) or a path via Node 5 (850).

[0065] Figure 9 is a diagram showing the transmission of Node 2 and the reception of surrounding nodes.

[0066] In the transmission frame (900), the transmitting node 2 (910) first transmits basic synchronization information through the Fc section (950) of the preamble. Then, in the control information section (920), it transmits control information necessary for receiving the payload through frequencies from Fn1_2 to Fn5_2.

[0067] The receiving side (960) first performs the process (965) of verifying the node number through the received Fc. Then, it changes to the Fn1 frequency of Node 2 (970), performs frequency hopping from Fn1 to Fn5 (975), and receives control information.

[0068] When control information is received, the payload reception information is checked (980), and based on this, the data is finally received through chaos reverse diffusion (985).

[0069] Through this process, synchronization is achieved between the transmitting node 2 and the receiving side, enabling the safe transmission and reception of the payload propagated by the chaos signal.

[0070] Figure 10 is a diagram showing the relay path when Node 2 transmits, illustrating the process of selecting a relay node and forming a relay path in multi-hop communication.

[0071] When Node 2 (1020) performs transmission within the network (1000), Node 1 (1010) and Node 4 (1040) that receive it operate as relay nodes if they satisfy the relay conditions.

[0072] Specifically, the transmission signal of the transmitting node 2 (1020) is received by node 1 (1010) and node 4 (1040) located at a distance of 1 hop, and these nodes determine whether to relay by checking the quality of the received signal and the packet sequence number. If the relay condition is satisfied, node 1 (1010) and node 4 (1040) each perform relay in the TDMA method at their respective allocated time slots.

[0073] Nodes within a 1-hop radius in the network (1000) determine the following conditions when they receive a transmission frame from transmitting node 2 (1020):

[0074] 1. Check whether the sender or receiver is its own node ID.

[0075] 2. Check if reception quality is above a certain threshold.

[0076] 3. Check if the packet sequence number is less than or equal to the specified value.

[0077] The relay nodes (Node 1 (1010), Node 4 (1040)) can be considered synchronized because they received the raw signal at the same time. The relay frame operates in TDMA mode and is transmitted at a specified timing based on the received frame.

[0078] At this time, to prevent collisions even if two or more relay nodes transmit simultaneously, each relay node starts transmission via Fc at the timing corresponding to its node number. Additionally, during relaying, the packet sequence number is incremented so that it is possible to determine which number packet is being relayed.

[0079] In this way, the signal transmitted through the relay of Node 1 (1010) and Node 4 (1040) is delivered to Node 3 (1030) and Node 5 (1050), enabling efficient communication across the entire network. Each relay node uses different frequencies and chaotic sequences to prevent mutual interference, and collisions between relay signals are also prevented due to TDMA-based sequential relaying.

[0080] FIG. 11 is a diagram showing the timing and frame structure of relay transmission, and illustrates the structure and transmission process of the original transmission packet (1110) and the relay transmission packet (1160).

[0081] In the raw transmission packet (1110), Node 2 (1020) acts as the transmitting node and transmits data through a transmission frame consisting of an Fc section (1115), a control information section (1120), and a payload section (1125).

[0082] In the relay transmission packet (1160), Node 1 (1010) and Node 4 (1040) operate as relay nodes, and each transmission frame is configured as follows:

[0083] - Relay frame of Node 1: Fc section (1164), control information section (1166), payload section (1168)

[0084] - Relay frame of Node 4: Fc section (1174), control information section (1176), payload section (1178)

[0085] Relay nodes perform relays in the following order:

[0086] 1. Transmit at different timings to avoid interference (1180)

[0087] 2. Avoid interference by transmitting at different frequencies at the same timing (1182)

[0088] 3. Differentiating signals by different spreading codes (1184)

[0089] Through this structure, relay nodes perform sequential relay using the TDMA method, and by using different frequencies and chaotic sequences, efficient relaying is possible without mutual interference.

[0090] As can be seen in the network configuration diagram, during raw transmission, Node 2 (1020) transmits to Node 1 (1010) and Node 4 (1040), and during relay transmission, Node 1 (1010) and Node 4 (1040) each perform relay in their assigned time slots to communicate up to Node 3 (1030) and Node 5 (1050).

[0091] FIG. 12 is a diagram showing in detail the relay packet transmission and reception process (1200).

[0092] During the relay packet transmission and reception process (1250), the frame of each node is configured as follows:

[0093] - Relay frame of Node 1: Fc section (1210), control information section (1250), payload section (1230a)

[0094] - Relay frame of Node 4: Fc section (1220), control information section (1260), payload section (1230b)

[0095] - Received frame of Node 5 (1230c): Received frame of the selected relay signal

[0096] The signal processing process of the receiving node 5 (1050) is as follows:

[0097] 1. Measure quality 3(1215) from Fc of Node 1

[0098] 2. Measure quality 5(1225) from Fc of Node 4

[0099] 3. Perform reception quality comparison (1230) (e.g., Node 1 < Node 4)

[0100] 4. Decision to receive from Node 4, which has better quality (1240)

[0101] 5. Change to Node 4's Fn and perform reception (1270)

[0102] 6. Check Chaos Sequence Information (1280)

[0103] 7. Data reception via chaos reverse diffusion (1290)

[0104] In the network configuration diagram below, data transmitted by Node 2 (1020) is relayed through Node 1 (1010) and Node 4 (1040) and delivered to Node 5 (1050). Node 5 selects and processes the signal from Node 4, which has better quality than the other two relayed signals.

[0105] Through this relay packet transmission and reception process, the receiving node can select and process the optimal signal among those received from multiple relay nodes, which contributes to improving communication reliability.

[0106] FIG. 13 is a diagram showing an example of operation of the multi-hop broadcasting and telecommunications of the present invention.

[0107] First, for network configuration, a unique ID is assigned to each node, and N communication devices are deployed. Each device is configured to generate frequency hopping patterns and chaos signals for each node. The location of each node is selected and deployed considering the communication range and transmission speed of the devices; the network configuration is completed solely through deployment, without any information exchange through inter-node communication.

[0108] In the transmission step (1310), communication is performed as follows according to the packet information (transmission node 1, packet number 1, reception node: broadcast):

[0109] - Node 1: Performs raw transmission (1 hop).

[0110] - Node 2: Relay decision set to reception quality 5

[0111] - Node 3: Decide to relay to reception quality 4

[0112] - Node 4: Does not relay to reception quality 2

[0113] In the relay stage (1350), relaying is performed as follows according to the packet information (transmitting node 1, packet number 2, receiving node: broadcast):

[0114] - Node 1: Since it is the transmitting node, it does not relay

[0115] - Node 2: Perform relay transmission (2 hops)

[0116] - Node 3: Perform relay transmission (2 hops)

[0117] - Node 4: No relay because packet number is 2

[0118] - Node 5: No relay because packet number is 2

[0119] This operational example demonstrates that when a broadcast signal is propagated within a network, all nodes that receive the raw signal transmitted by the transmitting node can perform relaying and transmit relay packets at the same time if their reception quality is above a certain level. Multi-hop broadcast signal propagation within the network is possible without the designation of a specific relay node, and this example illustrates broadcast communication when the relay hop limit is 2 or less and the relay quality limit is 3 or more.

[0120] Through this structure, rapid network configuration is possible without separate information exchange for network setup, and it can be effectively utilized, particularly in environments such as emergency deployment missions.

[0121] FIG. 14 is a diagram illustrating an example of operation of one-to-one and one-to-many communication of the present invention, showing an example of one-to-many communication in which the relay hop count limit is 3 or less and the relay quality limit is 3 or more.

[0122] In the transmission step (1410), communication is performed as follows according to the packet information (transmission node 1, packet number 1, reception node: node 5, node 6):

[0123] - Node 1: Performs raw transmission (1 hop).

[0124] - Node 2: Relay decision set to reception quality 5

[0125] - Node 3: Do not relay to reception quality 2

[0126] In the first relay stage (1430), relaying is performed as follows according to the packet information (sending node 1, packet number 2, receiving nodes: node 5, node 6):

[0127] - Node 1: Since it is the transmitting node, it does not relay

[0128] - Node 2: Perform relay transmission (2 hops)

[0129] - Node 3: Decide to relay to reception quality 4

[0130] - Node 4: Decide to relay to reception quality 4

[0131] - Node 5: Destination receiving node (no relay)

[0132] In the second relay stage (1450), relaying is performed as follows according to the packet information (sending node 1, packet number 3, receiving nodes: node 5, node 6):

[0133] - Node 1: Since it is the transmitting node, it does not relay

[0134] - Node 2: No relay because packet number is 3

[0135] - Node 3: Perform relay transmission (3 hops)

[0136] - Node 4: Perform relay transmission (3 hops)

[0137] - Node 5: Destination receiving node (no relay)

[0138] - Node 6: Destination receiving node (no relay)

[0139] This operational example demonstrates that one-to-one and one-to-many communication can be performed simply by designating the recipient, without the need to manage routing tables or separately specify relay nodes. One-to-one and one-to-many communication can be achieved by performing transmission and relaying in the same manner as broadcast communication, and determining whether to receive by simply identifying that one is the recipient.

[0140] Through this, it can be seen that efficient multi-hop communication is possible without special routing protocols, and that it can be usefully applied, especially in environments requiring rapid network configuration such as emergency deployment missions.

[0141] FIG. 15 is a block diagram showing the overall configuration and detailed configuration of each part of the ad-hoc hidden communication system (1500) of the present invention.

[0142] The transmitting unit (1510) includes an operation information management unit (1515), a transmission frame generation unit (1520), and a transmission signal generation unit (1530).

[0143] - The operation information management unit (1515) includes a service management unit responsible for network management and operation processing for broadcasting, one-to-one, and one-to-many services, and an operation parameter management unit that manages control parameters for frequency, node ID, and chaos sequence generation.

[0144] - The transmission frame generation unit (1520) includes a synchronization information generation unit that generates a sequence and time information for frame synchronization, a control information generation unit that generates chaotic sequence information and data length information of the payload, and a chaotic signal spreading unit that generates a chaotic sequence and spreads the transmission data using it.

[0145] - The transmission signal generation unit (1530) includes a frequency control unit that controls the frequency and bandwidth to be transmitted and a hopping pattern generation unit that generates a high-speed frequency hopping pattern of the preamble.

[0146] The relay unit (1532) includes the following configuration:

[0147] - The relay condition determination unit (1535) determines whether the sender or receiver of the received signal is its own node ID, whether the signal quality is above a threshold value, and whether the packet sequence number is below a relay limit value.

[0148] - The TDMA relay unit (1540) performs relays sequentially according to the time slot allocated to each node when a relay is determined, and manages the number of relays by increasing the packet sequence number during relay.

[0149] - The relay frame generation unit (1545) generates the Fc section of the relay node, avoids interference by assigning different Fn frequencies per node, and re-spreads the payload using different chaos sequences per node.

[0150] The receiving unit (1550) includes the following configuration:

[0151] - The receiving signal processing unit (1555) includes a frequency control unit that controls the frequency and bandwidth to be received, and a frame synchronization unit that performs reception synchronization and extracts synchronization information.

[0152] - The receiving frame analysis unit (1560) analyzes the extracted control information to obtain chaos sequence information.

[0153] - The chaos signal de-diffusion unit (1565) de-diffusions the payload using the acquired chaos sequence information.

[0154] This system configuration combines high-speed frequency hopping and chaotic signal spreading to achieve high anti-jamming and low detectability performance. Furthermore, since routing table management is unnecessary, rapid ad-hoc network configuration is possible without prior infrastructure or network synchronization procedures. Additionally, by utilizing TDMA-based sequential relaying and the low correlation characteristics of chaotic signals, stable communication without mutual interference is possible even during multiple relays.

[0155] FIG. 16 is a block diagram showing the detailed configuration of the transmission unit (1510) of the present invention, showing the detailed configuration of the operation information management unit (1515), the transmission frame generation unit (1520), and the transmission signal generation unit (1530).

[0156] The operational information management unit (1515) includes the following components:

[0157] - Service Management Department (1515a): Responsible for network management and operation processing for services such as broadcasting, one-to-one, and one-to-many communication, and controls transmission and reception procedures according to each communication method.

[0158] - Operation parameter management unit (1515b): Manages control parameters for frequency, node ID, and chaos sequence generation, and manages operation information considering the communication equipment's range and transmission speed.

[0159] The transmission frame generation unit (1520) includes the following configuration:

[0160] - Synchronization information generation unit (1520a): Generates synchronization information for the Fc section including a frame synchronization sequence, a node number, and a packet sequence number.

[0161] - Control information generation unit (1520b): Generates control information for the Fn interval including chaotic sequence information and data length information of the payload.

[0162] - Chaos signal spreading unit (1520c): Generates a chaotic sequence having non-periodicity and unpredictability, and uses it to spread the transmission data across the band.

[0163] The transmission signal generating unit (1530) includes the following configuration:

[0164] - Frequency control unit (1530a): Controls the frequency and bandwidth to be transmitted, and assigns frequencies for the Fc and Fn sections of the preamble and the Fp section of the payload.

[0165] - Jump pattern generation unit (1530b): Generates a high-speed frequency jump pattern to be used in the preamble section to ensure anti-jamming performance.

[0166] Through this transmitter configuration, it is possible to simultaneously achieve anti-jamming performance for the preamble via high-speed frequency hopping and low-observability performance for the payload using chaotic signals; in particular, rapid network configuration is possible without prior infrastructure due to the autonomous relay method that eliminates the need for routing table management.

[0167] FIG. 17 is a block diagram showing the detailed configuration of the relay unit (1532) of the present invention, and shows the detailed configuration of the relay condition determination unit (1535), the TDMA relay unit (1540), and the relay frame generation unit (1545).

[0168] The relay condition determination unit (1535) includes the following configuration:

[0169] - Signal quality measurement unit (1535a): Determines whether the quality of the received signal is above a preset threshold.

[0170] - Packet sequence number check unit (1535b): Checks whether the sequence number of the received packet is less than or equal to the relay limit value and limits the number of relays.

[0171] - Node ID verification unit (1535c): Checks whether the sender or receiver has its own node ID.

[0172] The TDMA relay unit (1540) includes the following configuration:

[0173] - Time slot allocation unit (1540a): Allocates different time slots to each relay node to prevent collisions during simultaneous transmission.

[0174] - Relay signal generation unit (1540b): Generates a signal to be relayed in an allocated time slot, and manages the number of relays by increasing the packet sequence number during relay.

[0175] The relay frame generation unit (1545) includes the following configuration:

[0176] - Chaos sequence conversion unit (1545a): Generates different chaos sequences for each relay node and uses them to redeploy the payload, thereby preventing interference between multiple relay signals.

[0177] The following effects can be achieved through the configuration of this relay unit:

[0178] 1. Separate routing table management is unnecessary due to autonomous relay node selection.

[0179] 2. TDMA-based sequential relay prevents collisions between relay signals.

[0180] 3. By using different chaos sequences for each node, stable communication is possible without mutual interference even during multiple relays.

[0181] 4. Packet sequence management can prevent unnecessary relaying and allow for the efficient use of network resources.

[0182] FIG. 18 is a block diagram showing the detailed configuration of the receiver (1550) of the present invention, showing the detailed configuration of the receiver signal processing unit (1555), the receiver frame analysis unit (1560), and the chaos signal despreading unit (1565).

[0183] The receiving signal processing unit (1555) includes the following configuration:

[0184] - Frequency control unit (1555a): Controls the frequency and bandwidth to be received, and sets the frequency of the Fc and Fn sections of the preamble and the Fp section of the payload.

[0185] - Frame synchronization unit (1555b): Detects a sequence for frame synchronization in the Fc section of the received preamble to obtain frame synchronization.

[0186] - Jump pattern generation unit (1555c): Generates a frequency jump pattern identical to that of the transmitting side and uses it when receiving the preamble.

[0187] The received frame analysis unit (1560) includes the following configuration:

[0188] - Control information analysis unit (1560a): Extracts chaotic sequence information and data length information of the payload in the Fn interval.

[0189] - Synchronization information analysis unit (1560b): Analyzes node number and packet sequence information in the Fc section.

[0190] The chaotic signal dediffusion unit (1565) includes the following configuration:

[0191] - Chaos sequence restoration unit (1565a): Generates a chaos sequence identical to that of the transmitting side based on the received control information.

[0192] - Data restoration unit (1565b): Recovers the original data by de-spreading the band-spread payload using the generated chaos sequence.

[0193] Through the configuration of this receiver, necessary information can be obtained from a preamble transmitted via high-speed frequency hopping, and based on this, the payload transmitted concealed by a chaotic signal can be successfully recovered. In addition, relay signals received via multiple paths can also be distinguished and received using different chaotic sequences for each node.

[0194] FIG. 19 shows a detailed flowchart of an ad-hoc hidden communication method of an ad-hoc hidden communication system (1500) according to the present invention.

[0195] First, the transmitter (1510) generates a chaotic signal having non-periodicity and unpredictability (S1902).

[0196] Next, the transmitting unit (1510) sets the structure of the transmission frame (S1904), the preamble is composed of a common frequency Fc for network synchronization and a frequency Fn for transmitting control information per node, and the payload is composed of a frequency Fp.

[0197] The transmitting unit (1510) generates a preamble (S1906), which includes synchronization information including a sequence for frame synchronization, a node number, and a packet number, and control information including chaotic sequence information of the payload and data length.

[0198] The transmitter (1510) uses the generated chaos signal to band spread the payload (S1908).

[0199] The ad-hoc hidden communication system determines whether to transmit or relay (S1910), and if it is to transmit, the transmitting unit (1510) transmits a preamble (S1912) and then transmits a bandwidth-spread payload (S1914).

[0200] In the case of relay, the relay unit (1532) checks the relay conditions (S1916), and checks the following conditions:

[0201] - Whether the sender or receiver is its own node ID

[0202] - Whether signal quality is above a threshold

[0203] - Whether the packet sequence number is less than or equal to the relay limit value

[0204] The relay unit (1532) determines whether the relay conditions are satisfied (S1918), and if the conditions are satisfied, performs TDMA-based relay (S1920). If the conditions are not satisfied, it checks the relay conditions again.

[0205] The receiver (1550) generates a chaotic sequence identical to that of the transmitter using control information obtained from the preamble (S1922), and restores the original data by de-spreading the payload using this (S1924).

[0206] Through this method, hidden communication combining high-speed frequency hopping and chaotic signal spreading is possible, and stable communication can be performed without mutual interference even during multiple relays using TDMA-based sequential relay. In addition, efficient multi-hop communication is possible without the need for separate routing table management.

[0207] Although it is described that all components constituting the embodiments of the present invention described above are combined or operate in combination, the present invention is not necessarily limited to such embodiments. That is, within the scope of the purpose of the present invention, all such components may be selectively combined in one or more ways to operate. Furthermore, while all such components may each be implemented as a single independent piece of hardware, they may also be implemented as a computer program having a program module that performs some or all of the combined functions in one or more pieces of hardware by selectively combining some or all of the components. Additionally, such a computer program may be stored on a computer-readable media such as a USB memory, CD disk, or flash memory, and read and executed by a computer to implement the embodiments of the present invention. Magnetic recording media, optical recording media, etc., may be included as recording media for the computer program.

[0208] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications, changes, and substitutions within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such embodiments and accompanying drawings. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

Claim 1 An ad-hoc hidden communication system using chaotic signals comprises: a transmitter that generates chaotic signals having non-periodicity and unpredictability, manages operational information, and generates transmission frames; a relay unit that determines whether to relay a signal received from the transmitter and performs relaying using the TDMA method; and a receiver that processes the received signal, analyzes frames, and despreads the chaotic signals, wherein the transmitter comprises: an operational information management unit that manages broadcasting, one-to-one, and one-to-many communication services; and a transmission frame generation unit that generates a transmission frame including a preamble performing narrowband high-speed frequency hopping and a payload spread into chaotic signals. A transmission signal generation unit that generates a transmission signal; wherein the transmission frame includes an Fc section that includes a sequence for frame synchronization, a node number, and a packet number and is transmitted over a common frequency for synchronization within the network, an Fn section that includes chaos sequence information and data length information of the payload and is transmitted over a frequency for transmitting node-specific control information, and an Fp section in which a payload band-spreaded with a chaos signal is transmitted, and the relay unit generates a different chaos sequence for each relay node and re-spreads the payload using the generated chaos sequence, multiple relay nodes receive the raw signal at the same time and transmit the relay frame at a specified timing based on the received frame, each relay node starts transmitting the relay frame through Fc at a timing corresponding to its node number, and the receiver measures the reception quality from each of the Fc of the multiple relay nodes, compares the measured reception quality to select the signal of the relay node with better reception quality, changes to the Fn of the selected relay node to receive, verifies the chaos sequence information from the Fn, and uses the verified chaos sequence information to transmit the payload Ad-hoc hidden communication system using a chaotic signal characterized by de-spreading. Claim 2 An ad-hoc hidden communication system using a chaotic signal according to claim 1, wherein the relay unit comprises: a relay condition determination unit that determines whether to relay a received signal; a TDMA relay unit that performs relaying using a TDMA (Time Divisional Multiple Access) method; and a relay frame generation unit that generates a relay frame. Claim 3 An ad-hoc hidden communication system using a chaotic signal according to claim 1, wherein the receiver comprises: a received signal processing unit that processes a received signal; a received frame analysis unit that analyzes a received frame; and a chaotic signal despreading unit that despreads a chaotic signal. Claim 4 An ad-hoc hidden communication system using a chaotic signal according to claim 2, wherein the relay condition determination unit comprises: a signal quality measurement unit for measuring signal quality; a packet sequence number verification unit for verifying a packet sequence number; and a node ID verification unit for verifying a node ID. Claim 5 An ad-hoc hidden communication system using a chaotic signal according to claim 2, wherein the TDMA relay unit comprises: a time slot allocation unit for allocating a time slot; and a relay signal generation unit for generating a relay signal. Claim 6 An ad-hoc hidden communication system using a chaos signal according to claim 2, wherein the relay frame generation unit comprises a chaos sequence conversion unit that generates different chaos sequences for each relay node and redeploys the payload. Claim 7 An ad-hoc hidden communication system using a chaotic signal according to claim 3, wherein the received signal processing unit comprises: a frequency control unit for controlling the frequency; a frame synchronization unit for performing frame synchronization; and a hopping pattern generation unit for generating a hopping pattern. Claim 8 An ad-hoc hidden communication system using a chaos signal, characterized in that, in paragraph 3, the received frame analysis unit comprises: a control information analysis unit that analyzes control information; and a synchronization information analysis unit that analyzes synchronization information. Claim 9 An ad-hoc hidden communication system using a chaotic signal according to claim 3, wherein the chaotic signal despreading unit comprises: a chaotic sequence restoration unit for restoring a chaotic sequence; and a data restoration unit for restoring data. Claim 10 A method for ad-hoc hidden communication using chaotic signals, comprising: a step in which a transmitter generates a chaotic signal having non-periodicity and unpredictability; a step in which the transmitter sets a transmission frame structure; a step in which the transmitter generates a preamble; a step in which the transmitter spreads the payload; a step in which the transmitter determines whether to transmit or relay; if transmission is in the case of transmission, a step in which the transmitter transmits the preamble and transmits the payload; if relay is in the case of relay, a step in which the relay unit checks relay conditions, determines whether relay conditions are satisfied, and performs TDMA (Time Divisional Multiple Access) based relay; and a step in which a receiver generates a chaotic sequence. The receiving unit includes a step of despreading the payload, wherein the transmission frame structure includes an Fc section transmitted via a common frequency for synchronization within the network, comprising a sequence for frame synchronization, a node number, and a packet number; an Fn section transmitted via a frequency for transmitting node-specific control information, comprising chaos sequence information and data length information of the payload; and an Fp section transmitted via a band-spread payload with a chaos signal. The step of performing the TDMA-based relay includes a plurality of relay nodes that have received the raw signal at the same time transmitting a relay frame at a specified timing based on the received frame, each relay node starting the transmission of the relay frame via Fc at a timing corresponding to its node number, and generating a different chaos sequence for each relay node and respreading the payload using the generated chaos sequence. The step of despreading the payload includes measuring the reception quality from each of the Fc of the plurality of relay nodes, comparing the measured reception quality to select the signal of the relay node with better reception quality, changing it to the Fn of the selected relay node for reception, and receiving the chaos sequence information from the Fn. An ad-hoc hidden communication method using a chaotic signal, characterized by verifying and de-spreading the payload using verified chaotic sequence information. Claim 11 delete Claim 12 A method for ad-hoc hidden communication using a chaotic signal according to claim 10, wherein the step of checking relay conditions comprises at least one of: a step of checking whether the sender or receiver of the received signal is its own node ID; a step of checking whether the quality of the received signal is above a preset threshold; and a step of checking whether the sequence number of the received packet is below a relay limit value. Claim 13 In claim 10, the step of performing the above TDMA-based relay is characterized by multiple relay nodes sequentially transmitting relay frames according to their respective allocated time slots, and transmitting by increasing the packet sequence number during relay, in an ad-hoc hidden communication method using a chaotic signal.

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