Hybrid pseudo-random number generator and system based on carbon-silicon fusion process

Abstract

The present invention relates to a hybrid pseudo-random number generator and system based on a carbon-silicon fusion process. A hybrid pseudo-random number generator based on a carbon-silicon process combined with a carbon nanotube field effect transistor technology is designed. The main body of the hybrid pseudo-random number generator consists of a linear feedback shift register module and an SM4 encryption and decryption module. By performing encryption and decryption operations on pseudo-random numbers generated by the linear feedback shift register module, the generated random number sequence is significantly improved in terms of randomness, uniformity and independence. The carbon nanotube field effect transistor technology is used to implement the linear feedback shift register module, which reduces circuit power consumption and improves the overall performance of the hybrid pseudo-random number generator.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a hybrid pseudo-random number generator and system based on a carbon-silicon fusion process. Background Art

[0002] Data encryption technology is an important means to ensure the security of electronic information. With the increase in the amount of information and the speed of transmission, hardware encryption has become the mainstream. As the first commercially available encryption algorithm, SM4 is widely recognized for its simple structure, fast encryption and decryption speed, and high security. It is widely used in fields such as data encryption storage and information encryption communication. At the same time, random numbers are crucial in computer security and are widely used in encryption algorithms. Generating high-quality random number sequences is essential to ensure the randomness of keys, which directly affects the security of information systems. Good random numbers can enhance the unpredictability of keys and effectively resist attacks such as cracking and cryptanalysis. Modern security protocols rely on high-quality random number generators (RNGs), whose output randomness must be rigorously tested and verified. In addition, the quality of random numbers also affects security mechanisms such as digital signatures, identity authentication, and key exchange. Therefore, efficient and secure random number generation technology is essential to improving the overall security of information systems.

[0003] Linear Feedback Shift Register (LFSR) is a pseudo-random number generator widely used in digital circuits. It is favored for its simple structure, fast speed and good uniformity. However, there are some shortcomings of traditional LFSR. First, the longest random number sequence period of n-bit LFSR is 2 n -1, resulting in the random number sequence actually generated being not uniform enough and unable to traverse all states, and may fall into a self-enclosed state, so a self-starting circuit needs to be designed to prevent deadlock. Secondly, LFSR only generates one random number per cycle, and the generation rate is low. These shortcomings limit the effectiveness of traditional LFSR in the application of high-performance pseudo-random number generators. Summary of the invention

[0004] Based on this, it is necessary to provide a hybrid pseudo-random number generator based on a carbon-silicon fusion process and an information system that can effectively improve the application performance of the pseudo-random number generator.

[0005] In order to achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] On the one hand, a hybrid pseudo-random number generator based on a carbon-silicon fusion process is provided, comprising a linear feedback shift register module, an SM4 encryption and decryption module and m adjustable frequency dividers, wherein the linear feedback shift register module is used to generate pseudo-random numbers, and the SM4 encryption and decryption module is used to perform encryption and decryption processing on the pseudo-random numbers output by the linear feedback shift register module as a key, a plain text and an encryption and decryption mode selection signal, and output a pseudo-random number sequence; m is the total number of the linear feedback shift register modules;

[0007] The linear feedback shift register module includes m-1 first linear feedback shift register modules made of carbon nanotube field effect transistors and a second linear feedback shift register module made of silicon-based complementary metal oxide semiconductor field effect transistors, m-2 first linear feedback shift register modules are used to output pseudo-random numbers as keys, one first linear feedback shift register module outputs a pseudo-random number as an encryption and decryption mode selection signal, the second linear feedback shift register module is used to output a pseudo-random number as plaintext, and m adjustable frequency dividers are respectively used to control the pseudo-random number generation frequency of each linear feedback shift register module.

[0008] In one embodiment, each linear feedback shift register module uses a jump output method to calculate and generate a pseudo-random number at any time after the register state at the current time ends.

[0009] In one embodiment, each linear feedback shift register module connects the register input at the head and the end to the register input after XORing its own feedback logic according to the two adjacent states with the least number of "1" in its own state transition diagram and then reconnects them to the register input.

[0010] In one embodiment, the second linear feedback shift register module includes a 128-stage linear feedback shift register.

[0011] On the other hand, an information system is also provided, including a communication device and the above-mentioned hybrid pseudo-random number generator based on the carbon-silicon fusion process, and the hybrid pseudo-random number generator based on the carbon-silicon fusion process is installed inside the communication device.

[0012] One of the above technical solutions has the following advantages and beneficial effects:

[0013] The above-mentioned hybrid pseudo-random number generator and system based on carbon-silicon fusion process designs a hybrid pseudo-random number generator based on carbon-silicon process combined with carbon nanotube field effect transistor technology. The main body of the hybrid pseudo-random number generator consists of two parts: a linear feedback shift register module and an SM4 encryption and decryption module. By performing encryption and decryption operations on the pseudo-random numbers generated by the linear feedback shift register module, the generated pseudo-random number sequence has significant improvements in randomness, uniformity and independence; the use of CNFET technology to implement the linear feedback shift register module reduces circuit power consumption and improves the overall performance of the hybrid pseudo-random number generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 Schematic diagram of the overall structure of a hybrid pseudo-random number generator based on a carbon-silicon fusion process in one embodiment;

[0017] Figure 2 A schematic diagram of the structure of an improved LFSR in one embodiment;

[0018] Figure 3 FIG. 4 is a state transition diagram of an improved LFSR in one embodiment. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0020] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings in the embodiment diagram of the present invention.

[0021] Since the advent of Moore's Law, the integrated circuit industry has experienced rapid development, with chip process sizes shrinking and integration gradually increasing. This process has promoted the development of information technology and promoted innovation in the fields of computers, communications, and consumer electronics. However, as the complementary metal oxide semiconductor (CMOS) process enters the 10nm node, Moore's Law has gradually shown its limitations. Continuing to reduce the size of transistors to increase integration not only significantly increases manufacturing costs, but also leads to excessive power consumption per unit area of ​​the chip, seriously affecting the reliability of the chip.

[0022] As the global semiconductor industry enters the post-Moore era, carbon nanotube field-effect transistors (CNFETs) have become the most promising choice among new semiconductor materials. CNFETs have superior electrical properties and high carrier transfer capabilities, and can significantly improve circuit performance while consuming low power. They are particularly suitable for mobile devices and high-performance computing. Compared with traditional metal-oxide semiconductor field-effect transistors (MOSFETs), CNFETs can provide better energy delay product (EDP) advantages. In addition, the working principle of CNFETs is similar to that of CMOS devices, and the design can directly utilize the existing CMOS architecture, thereby reducing design complexity and development costs. Its manufacturing process is compatible with CMOS, which will help accelerate the commercialization of CNFET technology. Therefore, in-depth research on the application of CNFETs has important academic and engineering significance.

[0023] This application proposes a high-performance hybrid pseudo-random number generator combining a linear feedback shift register and SM4, aiming to provide a pseudo-random number sequence with better randomness, uniformity and independence. A hybrid circuit using carbon nanotube field effect transistors and Si (silicon) is used to improve the actual performance of the circuit and reduce the power consumption of the circuit by taking advantage of the low power consumption and high performance of carbon nanotube field effect transistors, solving the problem of slow random number generation rate and uneven distribution of random numbers "0" and "1" generated by traditional linear feedback shift register circuits.

[0024] In one embodiment, see Figure 1, a hybrid pseudo-random number generator based on carbon-silicon fusion process is provided, including a linear feedback shift register module, an SM4 encryption and decryption module and m adjustable frequency dividers, the linear feedback shift register module is used to generate pseudo-random numbers, the SM4 encryption and decryption module is used to use the pseudo-random numbers output by the linear feedback shift register module as keys, plain text and encryption and decryption mode selection signals for encryption and decryption processing, and output pseudo-random number sequences; m is the total number of linear feedback shift register modules. The linear feedback shift register module includes m-1 first linear feedback shift register modules made of carbon nanotube field effect transistors and a second linear feedback shift register module made of silicon-based complementary metal oxide semiconductor field effect transistors, m-2 first linear feedback shift register modules are used to output pseudo-random numbers as keys, one first linear feedback shift register module outputs pseudo-random numbers as encryption and decryption mode selection signals, the second linear feedback shift register module is used to output pseudo-random numbers as plain text, and the m adjustable frequency dividers are used to control the pseudo-random number generation frequency of each linear feedback shift register module.

[0025] It can be understood that this embodiment proposes an innovative design for generating a pseudo-random number sequence with higher randomness, uniformity and independence, while reducing circuit power consumption and improving performance. First, in view of the shortcomings of the traditional LFSR circuit, its random number generation rate and the uneven distribution of the generated random numbers "0" and "1" are improved; then a hybrid pseudo-random number generator based on the combination of carbon nanotube field effect transistors and silicon (based on carbon silicon fusion process) is designed. The overall architecture of the hybrid pseudo-random number generator designed in this embodiment can be as follows Figure 1 As shown in FIG. 1 , its circuit structure mainly consists of an improved linear feedback shift register module and an SM4 encryption and decryption module. The improved linear feedback shift register module is used to generate pseudo-random numbers. The SM4 encryption and decryption module is used to encrypt and decrypt the pseudo-random numbers output by the linear feedback shift register module as a key, plain text (data) and an encryption and decryption mode selection signal (slt) to generate a better quality pseudo-random number sequence. Function F is the function F (i.e., the round function) of the SM4 encryption and decryption algorithm, and Reg is the pipeline register in the pipeline of the SM4 encryption and decryption module.

[0026] It should be noted that the underlying circuit structure of each of the above-mentioned linear feedback shift register modules can be the same as the circuit structure of the existing linear feedback shift register in the art. The main difference between each linear feedback shift register module and the existing linear feedback shift register in the art is that the former uses CNFET to replace the CMOS device used in the latter, and at the same time, an adjustable frequency divider is added to each input end of the former, and the input form of the former can be modified by software settings (as shown below). The above-mentioned SM4 encryption and decryption module can directly use the existing SM4 pipeline core unit, and the adjustable frequency divider can also directly use the existing frequency divider. The specific specifications can be selected according to actual use needs.

[0027] The above-mentioned hybrid pseudo-random number generator based on carbon-silicon fusion process has designed a hybrid pseudo-random number generator based on carbon-silicon process combined with CNFET technology. The main body of the hybrid pseudo-random number generator consists of two parts: a linear feedback shift register module and an SM4 encryption and decryption module. By performing encryption and decryption operations on the pseudo-random numbers generated by the linear feedback shift register module, the generated pseudo-random number sequence has significant improvements in randomness, uniformity and independence; the use of CNFET technology to implement the linear feedback shift register module reduces circuit power consumption and improves the overall performance of the hybrid pseudo-random number generator.

[0028] Pseudo-random number generators (PRNGs) continuously flip levels in actual circuits, making power consumption an important limiting factor in their performance. Compared with traditional silicon-based circuits, carbon nanotube field-effect transistors, as new semiconductor devices, have shown significant advantages in achieving low-power and high-performance circuits. Carbon nanotube field-effect transistors mainly use carbon nanotubes as conductive channels. Compared with traditional MOSFETs, carbon nanotube field-effect transistors have lower switching threshold voltages, resulting in a significant decrease in static power consumption under the same operating conditions. This feature makes carbon nanotube field-effect transistors particularly suitable for fast-switching pseudo-random number generator circuits when operating at high frequencies. In addition, the carrier mobility of carbon nanotubes is much higher than that of silicon, which means that carbon nanotube field-effect transistors can complete level flips in a shorter time, thereby increasing the operating frequency of the circuit and generating pseudo-random number sequences at a faster speed.

[0029] The structure of carbon nanotube field effect transistors can also achieve smaller sizes, which helps to improve the integration density of chips, which allows more functions to be integrated into a single chip, thereby optimizing the design and reducing costs. Finally, in high temperature environments, the performance of carbon nanotube field effect transistors is more stable, which shows that circuits based on carbon nanotube field effect transistors have better reliability and stability. In summary, the pseudo-random number circuit designed based on carbon nanotube field effect transistors can effectively reduce power consumption, significantly improve performance, and provide higher stability.

[0030] Specifically, Figure 1 The overall architecture of the hybrid pseudo-random number generator based on the carbon-silicon fusion process is demonstrated. The design of this architecture uses a linear feedback shift register module to generate a pseudo-random number sequence, and provides these pseudo-random number sequences as input keys, plaintext, and encryption and decryption mode selection signals to the SM4 encryption and decryption module. The SM4 encryption and decryption module encrypts and decrypts the received data to generate a new pseudo-random number sequence, thereby enhancing the complexity and security of the random number. In this design, two linear feedback shift register modules (such as the first linear feedback shift register module CNFET-LFSR and the second linear feedback shift register module Si-LFSR) are used to generate keys, input plaintext, and encryption and decryption mode selection signals, respectively.

[0031] The improved design may include three independent linear feedback shift register modules, each of which has a pseudo-random number generation frequency controlled by an adjustable frequency divider, so as to provide different frequency inputs to the SM4 encryption and decryption module, thereby generating a diverse random number sequence. In addition, the linear feedback shift register module for generating keys and encryption and decryption mode selection signals is implemented using carbon nanotube field effect transistors to reduce overall power consumption and improve circuit performance.

[0032] First, the improvement of the traditional linear feedback shift register structure solves the two shortcomings of the traditional linear feedback shift register. Taking the first linear feedback shift register module with 4 levels (i.e., CNFET-LFSR (n=4)) as an example, the circuit of the first linear feedback shift register module can be as follows: Figure 2 As shown in the figure, four D flip-flops are used, clk is the clock signal, and rst is the reset signal. In the traditional 4-stage linear feedback shift register express The register status at the moment, then The state at the moment can be expressed as: Then we can deduce The state can be expressed as: So through The status of the four registers at the moment can be calculated at one time The values ​​of all register states at the moment: , , so according to the above formula, we can The moment is calculated directly by calculation The values ​​of the 4 register states at the time.

[0033] In one embodiment, each linear feedback shift register module calculates and generates a pseudo-random number at any time after the register state at the current time ends by means of a jump output.

[0034] It is understandable that if the state at time i is skipped after it ends, , and moment, directly enter moment, 4 new random numbers can be calculated and generated directly in one moment (i.e., jump output), which effectively improves the calculation efficiency. In this way, the problem of slow random number generation rate of traditional linear feedback shift register can be solved by jumping forward 4 times each time.

[0035] Next, the problem that the traditional linear feedback shift register cannot traverse all states is solved. Taking the first linear feedback shift register module with a level of 4 as an example, the traditional linear feedback shift register will add a self-starting circuit to avoid entering a self-enclosed deadlock state.

[0036] In one embodiment, each linear feedback shift register module connects the register input at the head and the end to the register input after XORing its own feedback logic according to the two adjacent states with the least number of "1" in its own state transition diagram and then reconnects them to the register input.

[0037] Specifically, the original feedback function Modified to: If you want to add this function after implementing the jump output improvement, you can follow the LFSR state transition diagram after implementing the jump output, such as Figure 3 As shown, two adjacent states are selected and the all-0 state is inserted between the two states. For example, in this embodiment, two adjacent states can be selected as "1000" and "1001". The reason for selecting two adjacent states is that these two adjacent states contain the least number of "1", so when modifying the circuit of the feedback function, the hardware overhead is minimized. It can be understood that those skilled in the art can also select other two adjacent states with the least number of "1" by the same logic.

[0038] According to the selection of two adjacent states, the register input terminals at the beginning and end of the linear feedback shift register module are respectively XORed with the feedback logic (i.e. Figure 2 In Operation) and then reconnect the input. The state at a moment can be expressed as: , Although this embodiment only takes a 4-stage LFSR as an example, in fact, any LFSR with any number of stages can be improved with this design concept. For LFSRs with different stages, the jump stages are different, and the LFSR jump stages can be customized according to the hardware overhead and random number generation rate requirements. When choosing to insert the all-"0" state, find the two adjacent items with the least "1" bit change, and compare their corresponding state functions. In this way, the all-"0" state can be inserted in the most resource-saving way.

[0039] In one embodiment, the second linear feedback shift register module includes a 128-stage linear feedback shift register.

[0040] It can be understood that an improved 128-level second linear feedback shift register module Si-LFSR can be used to provide plain text input. In addition, 32 improved 4-level first linear feedback shift register modules CNFET-LFSR with different initial states are combined to provide key input, and an improved 4-level first linear feedback shift register module CNFET-LFSR is used to generate an encryption and decryption mode selection signal. Since the circuit scale supported by CNFET is limited, a 4-level linear feedback shift register can be selected for implementation.

[0041] However, the period of the pseudo-random number sequence formed by splicing these 32 4-level linear feedback shift registers is 16, which may cause the output data to present a shorter period when used as plaintext input, which does not constitute a true pseudo-random number. Therefore, the plaintext input is implemented using the 128-level second linear feedback shift register module Si-LFSR to ensure that the generated pseudo-random number sequence has sufficient complexity and randomness.

[0042] It should be noted that the above specific value of n in this specification is only an example. Those skilled in the art can implement module design under other n values ​​in accordance with the design concept of this application and actual application needs to achieve the same or similar functions.

[0043] The encryption and decryption mode selection signal is also generated by CNFET-LFSR to disrupt the encryption and decryption operation mode, further enhance the randomness of the pseudo-random number sequence, and prevent attackers from inferring the encryption and decryption mode by analyzing the output pseudo-random number sequence. The SM4 encryption and decryption algorithm uses a 32-level pipeline structure to increase the encryption and decryption speed, thereby increasing the rate of pseudo-random number generation and ensuring that the system can respond quickly and generate high-quality pseudo-random numbers.

[0044] Figure 1It also shows that an adjustable frequency divider is set for each input interface, and the generation rate of the input information is controlled by the adjustable frequency divider, thereby affecting the generation effect of the pseudo-random number sequence. The frequency division settings of different adjustable frequency dividers can flexibly adjust the response time and data flow rate of the system, thereby optimizing the circuit performance. The frequency division of the three module input information and the randomly generated encryption and decryption mode selection signal can effectively extend the period of the pseudo-random number sequence and avoid strong correlation. This design not only improves the randomness and complexity of the pseudo-random sequence, but also enhances security. By configuring different frequencies of the adjustable frequency divider, a variety of pseudo-random number sequences can be generated to meet different application requirements, thereby further improving the overall performance and security of the system. In this way, a more effective solution is provided for efficient and secure pseudo-random number generation, which is suitable for various information security and encryption applications.

[0045] In general, the hybrid pseudo-random number generator based on the carbon-silicon fusion process can effectively adjust the generation rate of input information by configuring an adjustable divider, thereby affecting the effect of the key, plaintext and encryption and decryption mode selection signal generated by the linear feedback shift register module. Each adjustable divider setting can flexibly adjust the response time and data flow rate of the system, thereby optimizing the circuit performance and ensuring the efficiency and stability of pseudo-random number generation. The generated pseudo-random number will be sent to the SM4 encryption and decryption module, which is responsible for encrypting or decrypting the input information and generating a series of new pseudo-random numbers. The SM4 encryption and decryption module can efficiently process input data through a pipeline structure, improve the encryption and decryption speed, and further improve the rate and quality of pseudo-random number generation.

[0046] In some implementations, after the pseudo-random number generation is completed, the generated pseudo-random number sequence may be subjected to an existing NIST SP800-22 randomness test to evaluate whether the pseudo-random number sequence meets the characteristics of a true random number.

[0047] In one embodiment, an information system is further provided, including a communication device and the above-mentioned hybrid pseudo-random number generator based on the carbon-silicon fusion process, and the hybrid pseudo-random number generator based on the carbon-silicon fusion process is mounted inside the communication device.

[0048] It can be understood that the explanation of the above-mentioned components can be understood in the same way as the corresponding features of the hybrid pseudo-random number generator based on the carbon-silicon fusion process, and will not be repeated in this embodiment. The communication equipment refers to the components of the existing communication equipment in the information system except for the above-mentioned improved hybrid pseudo-random number generator based on the carbon-silicon fusion process, which can be understood in the same way according to the existing structures of different information systems, and will not be described in detail in this specification.

[0049] The above information system has significantly improved the randomness, uniformity and independence of the generated random number sequences, and has a high level of information security.

[0050] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In the present invention, unless otherwise clearly defined and specified, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A hybrid pseudo-random number generator based on carbon-silicon fusion process, characterized in that: It includes a linear feedback shift register module, an SM4 encryption and decryption module and m adjustable frequency dividers, wherein the linear feedback shift register module is used to generate pseudo-random numbers, and the SM4 encryption and decryption module is used to use the pseudo-random numbers output by the linear feedback shift register module as a key, plain text and encryption and decryption mode selection signal to perform encryption and decryption processing, and output a pseudo-random number sequence; m is the total number of the linear feedback shift register modules; the encryption and decryption mode selection signal is an slt signal; The linear feedback shift register module includes m-1 first linear feedback shift register modules made of carbon nanotube field effect transistors and a second linear feedback shift register module made of silicon-based complementary metal oxide semiconductor field effect transistors, m-2 of the first linear feedback shift register modules are used to output pseudo-random numbers as the keys, one of the first linear feedback shift register modules outputs a pseudo-random number as the encryption and decryption mode selection signal, the second linear feedback shift register module is used to output a pseudo-random number as the plaintext, and the m adjustable frequency dividers are respectively used to control the pseudo-random number generation frequency of each of the linear feedback shift register modules.

2. The hybrid pseudo-random number generator based on carbon-silicon fusion process according to claim 1, characterized in that: Each of the linear feedback shift register modules uses a jump output method to calculate and generate a pseudo-random number at any time after the register state at the current time ends.

3. The hybrid pseudo-random number generator based on carbon-silicon fusion process according to claim 2, characterized in that: Each linear feedback shift register module respectively connects the register input terminals at the head and the tail to the register input terminals after XORing with the self-starting feedback logic according to the two adjacent states with the least number of "1" in its own state transition diagram and then reconnects them to the register input terminals.

4. The hybrid pseudo-random number generator based on carbon-silicon fusion process according to any one of claims 1 to 3, characterized in that: The second linear feedback shift register module includes a 128-stage linear feedback shift register.

5. An information system, characterized in that: It comprises a communication device and a hybrid pseudo-random number generator based on a carbon-silicon fusion process as described in any one of claims 1 to 4, wherein the hybrid pseudo-random number generator based on a carbon-silicon fusion process is mounted inside the communication device.

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