CN116017423A

CN116017423A - Wireless ad hoc network safe transmission method based on USRP

Info

Publication number: CN116017423A
Application number: CN202211635086.6A
Authority: CN
Inventors: 丁宁; 严纬华; 庄东曙; 王龙龙; 孙正健
Original assignee: Nanjing Panda Electronics Co Ltd; Nanjing Panda Communication Technology Co Ltd
Current assignee: Nanjing Panda Electronics Co Ltd; Nanjing Panda Communication Technology Co Ltd
Priority date: 2022-12-19
Filing date: 2022-12-19
Publication date: 2023-04-25

Abstract

The invention provides a wireless self-organizing network safe transmission method based on USRP, which adopts USRP software radio equipment to build a wireless self-organizing network communication platform and designs and realizes a physical layer key extraction scheme based on channel state information. LabVIEW software programming realizes channel state information extraction, and carries out quantization, key negotiation and privacy amplification on the extracted channel state information, and finally generates an available key for encryption of the transmission data of the ad hoc network; in the key negotiation stage, a mode of correcting errors before checking is adopted to carry out consistency negotiation on the key, so that the key inconsistency rate is effectively reduced, and the key generation rate is improved; the invention can set corresponding communication nodes according to different ad hoc network communication scenes, has higher flexibility and expansibility, and solves the problems of difficult key distribution, high calculation complexity and more consumed system resources in the traditional security mechanism.

Description

Wireless ad hoc network safe transmission method based on USRP

Technical Field

The invention belongs to the field of communication, and particularly relates to a wireless ad hoc network safe transmission method based on USRP.

Background

In recent years, the need for low latency high quality communications has driven the rapid development of wireless communication technology. Various wireless communication technologies greatly facilitate the lives of people, and the most common wireless communication technologies are cellular communication, WIFI and the like. These wireless communication technologies rely on a fixed infrastructure to enable communication, such as cellular telephones that rely on base stations to transmit data, and WIFI networks that rely on access points to forward data. However, in the case of military operations, flood control, disaster relief, emergency rescue, etc., conditions for constructing infrastructure are lacking. Under the conditions, the wireless ad hoc network which does not depend on infrastructure, is flexible, changeable and rapidly deployed has wide application prospect. The wireless ad hoc network does not adopt centralized management, and each node performs communication transmission by self-networking. Each node in the wireless ad hoc network adopts a wireless communication mode to carry out data transmission, and the broadcasting characteristic of radio waves provides natural conditions for an attacker to implement malicious attacks. Today, the volume of transmitted information is larger and larger, the requirements on the safety of communication are higher and higher, especially in the fields of battlefield, medical treatment, personal privacy and the like, once the safety of the communication is destroyed due to the attack of a wireless network in the communication process, the problems of the stealing of battlefield instructions, the leakage of medical data and personal privacy and the like can be caused.

The current information transmission safety protection method mainly adopts a data encryption technology. The method mainly protects information transmitted by legal users, even if the information is intercepted by an attacker, the attacker cannot obtain useful information, and the confidentiality of the information is guaranteed; in the conventional security mechanism, the implementation of the security protection means requires a trusted third party to distribute and manage the secret key. However, the nodes in the wireless ad hoc network have strong dynamics, so that key distribution in the traditional security mechanism has certain difficulty. Furthermore, conventional security mechanisms are based on cryptography, and require various complex encryption algorithms to ensure the security of information, which requires hardware devices to possess certain computing power and resources. The node computing capacity and resources in the wireless ad hoc network are limited, and the computing capacity and resources of each node are not necessarily capable of guaranteeing the computing requirements of the complex cryptographic algorithm. Based on the problems of the traditional security mechanism, the physical layer key extraction of the wireless channel characteristics can directly extract the key at the positions of both legal communication parties without the need of a third party for key distribution management, thereby effectively solving the traditional key distribution problem.

As early as 1949 shannon research on the problem of secure communication from the point of information theory, put forward the concept of perfect encryption, the concept points out that if encryption of plaintext M by different secret keys K each time, namely one secret at a time, is satisfied, and the length of secret key K is equal to or greater than the length of plaintext M, then the mutual information of ciphertext C and plaintext M can be zero, and any message about plaintext cannot be deduced from ciphertext. 1993. Maurer et al have proposed that legal communication parties can generate a key by sending random signals to each other, with the random signals being the shared random source of the key. In 1995 Hassan indicated that both parties of legal communication can utilize reciprocity, randomness and uniqueness of channels to estimate uplink and downlink channels in coherence time to obtain an extracted encryption key, so as to realize encrypted communication. The above research lays a theoretical foundation for physical layer key extraction. According to the principle of channel reciprocity, both communication parties have consistency in estimating the characteristics of the channel. By utilizing the characteristic, both communication parties can use the common channel characteristics as a random source of the key to extract the physical layer key. The main aim of the physical layer key extraction technology research is to improve the key generation rate on the premise of ensuring that physical layer keys extracted by legal communication parties have consistency and randomness.

Disclosure of Invention

The invention aims at: a wireless ad hoc network communication platform is built by using USRP software radio equipment, and a physical layer key extraction scheme based on channel state information is designed and realized for generating an available key and realizing encryption of ad hoc network transmission data.

In order to achieve the above purpose, the present invention provides the following technical solutions: a wireless self-organizing network safe transmission method based on USRP, based on the creation of 1 communication master node and at least 2 destination nodes, the communication master node forms legal communication groups with each destination node respectively, each legal communication group generates a secret key, and the method comprises the following steps:

s1: the method comprises the steps that a main node and a target node in a legal communication group alternately send detection signals in coherent time, and receive the detection signals through an antenna to perform channel estimation, wherein the main node and the target node respectively measure channel frequency domain response amplitude values;

s2: the main node and the target node in the legal communication group respectively quantize the measured frequency domain response amplitude of the channel to obtain respective corresponding initial key bit sequences;

s3: the master node and the destination node in the legal communication group respectively carry out interleaving treatment on the obtained initial key bit sequence, then the master node and the destination node cooperate to carry out key error correction and CRC check, and finally the master node and the destination node respectively obtain the key bit sequence with consistency after consistency negotiation;

s4: and the master node and the destination node in the legal communication group respectively carry out hash operation on the key bit sequence with consistency obtained in the step S3 to obtain a key finally used for secure encryption.

Further, a system for realizing the USRP-based wireless ad hoc network safe transmission method comprises a channel estimation module, a quantization module, a negotiation module and a privacy amplification module; the channel estimation module is used for carrying out channel estimation on the received detection signals to obtain channel frequency response amplitude values; the quantization module is used for performing quantization on the response amplitude of the channel frequency domain in the S2 to obtain an initial key bit sequence; the negotiation module is used for executing consistency negotiation between the communication nodes in the S3; the privacy amplification module is used for executing the hash operation on the key bit sequence in the S4 to obtain a final key.

Further, the foregoing negotiation module includes a master node negotiation end and each destination node negotiation end, where each negotiation end includes an error correction module and a CRC check module.

Further, the master node end error correction module is configured to generate error correction information and send the error correction information to each destination node end error correction module, where each destination node end error correction module performs key error correction according to the received error correction information.

Further, each of the foregoing destination node end verification modules is configured to perform CRC operation on the destination node end key after error correction, and send generated CRC verification information to the master node end verification module, where after the master node end verification module receives the CRC verification information from the destination node end, the master node end verification module performs CRC operation on the key of the master node end, and then compares the generated master node end CRC verification information with the received destination node end CRC verification information to obtain a verification result.

Furthermore, the data security transmission of each legal communication group of the wireless ad hoc network is based on the construction of a USRP platform, and the construction of the USRP platform comprises a programming USRP configuration module, an OFDM modulation demodulation module, a frame identification module, a frame grouping module and a frame analysis module.

Compared with the prior art, the wireless ad hoc network safe transmission method based on USRP has the following technical effects:

1) The invention utilizes USRP radio equipment to build a wireless ad hoc network communication platform and realize key extraction, solves the problems of difficult key distribution, high calculation complexity and more consumed system resources in the traditional safety mechanism, improves the safety of communication between wireless ad hoc network nodes, and provides a new technical approach for enhancing the safe transmission of information in the wireless ad hoc network;

2) The invention designs a physical layer key extraction scheme based on the combination of error correction and verification in the communication process of an ad hoc network, and adopts a mode of error correction before verification to carry out consistency negotiation on a key in a key negotiation stage;

3) The wireless ad hoc network physical key extraction realization system developed at the time has higher flexibility and expansibility, and a user can set corresponding communication nodes according to different ad hoc network communication scenes.

Drawings

FIG. 1 is a diagram of an ad hoc network communication model in accordance with an embodiment of the present invention;

FIG. 2 is a diagram of a host computer software interface in accordance with the present invention;

FIG. 3 is a USRP transmission flow chart of the invention;

FIG. 4 is a USRP receiving flow chart of the invention;

fig. 5 is a block diagram of an OFDM modulation scheme in accordance with the present invention;

FIG. 6 is a diagram of an insert pilot module of the present invention;

fig. 7 is a block diagram of an insert virtual subcarrier of the present invention;

figure 8 is a diagram of an insert cyclic prefix module of the present invention;

fig. 9 is a block diagram of a beacon frame packet according to the present invention;

FIG. 10 is a block diagram of a frame identification of the present invention;

FIG. 11 is a block diagram of a frame parsing module of the present invention;

fig. 12 is a block diagram of a channel estimation of the present invention;

FIG. 13 is a quantization block diagram of the present invention;

FIG. 14 is a diagram of a master node A-side error correction module of the present invention;

FIG. 15 is a block diagram of the end error correction module of destination node B, C, D of the present invention;

FIG. 16 is a node B, C, D side CRC check map of the present invention;

FIG. 17 is a master node A-side CRC check chart of the present invention;

fig. 18 is a privacy amplification block diagram of the present invention.

Detailed Description

For a better understanding of the technical content of the present invention, specific examples are set forth below, along with the accompanying drawings.

Aspects of the invention are described herein with reference to the drawings, in which there are shown many illustrative embodiments. The embodiments of the present invention are not limited to the embodiments described in the drawings. It is to be understood that this invention is capable of being carried out by any of the various concepts and embodiments described above and as such described in detail below, since the disclosed concepts and embodiments are not limited to any implementation. Additionally, some aspects of the disclosure may be used alone or in any suitable combination with other aspects of the disclosure.

As shown in fig. 1 and 2, in this embodiment, a wireless AD hoc network communication system is built by using 4 single-antenna USRP devices, and a wireless AD hoc network simulation platform is built, where the wireless AD hoc network simulation platform includes a communication master node a and 3 destination nodes B, C, D, so as to form 3 legal communication groups AB, AC, and AD; the building of the wireless ad hoc network simulation platform comprises a USRP configuration module, an OFDM modulation demodulation module, a frame identification module, a frame grouping module and a frame analysis module.

In this embodiment, the USRP configuration module includes a transmitting end configuration module and a receiving end configuration module, where the transmitting end configuration module mainly includes: the functions of niUSRP Open Tx session.vi, niUSRP configuration signal.vi, niUSRP Write Tx data.vi and niUSRP Close session.vi are respectively: opening a USRP session, configuring USRP send parameters, writing data to the buffer, and closing the USRP session. As shown in fig. 3, a complete transmission procedure includes:

1) Inputting the IP address of the USRP to the niUSRP OpenTx session. Vi, wherein the vi outputs a USRP session handle, and the USRP session handle stores the setting information of the USRP;

2) The niUSRP configuration signal.vi is mainly used for configuring the transmission parameters of USRP, and the common parameters are mainly as follows: IQ Rate (IQ Rate), carrier frequency (Carrier Frequency), antenna Gain (Gain), and Antenna path (Active Antenna);

3) After the USRP parameter configuration is finished, the IQ data is required to be sent out through the USRP, and the IQ data is only required to be written into the USRP cache. The function realized by niUSRP Write Tx data vi is that IQ data to be transmitted is written into USRP buffer and transmitted through USRP antenna, and the data types mainly include: a double-precision complex type, a double-precision complex waveform type, and a double-precision complex cluster type. The vi defaults to send the write-once cache data, so the vi needs to be nested in the While loop to realize the continuous sending of the data;

4) When the While loop stops, the niUSRP Write Tx data.vi runs to end and passes the USRP session handle to the niUSRP Close session.vi, which closes the USRP session and ends the transmission.

The receiving end configuration module mainly comprises: niUSRP Open Rx session.vi, niUSRP configuration signal.vi, niUSRP initiator.vi, niUSRP latch Rx data.vi, niUSRP Abort.vi, and niUSRP Close session.vi. The functions are respectively as follows: opening a receiving session, configuring USRP parameters, initializing a state, starting to collect signals, reading collected signal data, stopping collection and closing the session. As shown in fig. 4, the complete USRP receiving procedure includes:

1) Inputting a parameter IP address to niUSRP OpenRx session.vi, opening a USRP receiving session and outputting a receiving session handle;

2) The niUSRP configuration signal.vi configures the receiving parameters, and the receiving end configures the same parameters as the transmitting end;

3) After the configuration parameters of the receiving end are finished, running niUSRP initial.vi, wherein the vi is used for initializing the USRP state and starting to acquire signals, and storing signal data into a buffer area to wait for reading;

4) After the niUSRP initial.vi collects the signal data and stores the signal data into the buffer area, the niUSRP Fetch Rx data.vi which is nested in the While cycle is operated to continuously read the data of the buffer area, and the read data type is consistent with that sent by the sending end;

5) After the end of the data reading, niUSRP antibody.vi is responsible for stopping signal acquisition. And finally, running the niUSRP Close session.vi to Close the receiving session, and ending the receiving.

As shown in fig. 5, in the OFDM modulation and demodulation module of this embodiment, the OFDM modulation and transmission module implements parallel/serial conversion, pilot frequency insertion, virtual subcarrier insertion, IFFT, CP insertion, coarse synchronization and fine synchronization. After the data stream enters the OFDM modulation module, serial-parallel conversion is firstly carried out, the serial data stream is converted into parallel data stream, and each row has the length of 125 data symbols. A pilot is then inserted for each data stream. The pilot insertion module is shown in fig. 6. The pilot symbols are mainly used for channel estimation and equalization, so that the receiving party can better recover the data. First, a pilot symbol is inserted in the data header, then, every five data symbols are inserted with a pilot symbol length of 125 before the data symbols are inserted into the pilot, and the length of the output symbol after the data symbols are inserted is 150. After pilot insertion, the data symbol length becomes 150. Then, virtual subcarriers are inserted to cancel the dc component in the signal. The insertion of virtual subcarriers as shown in fig. 7, an all-zero complex array is first initialized, and the input data is split into 75 data symbols. The initialized array is then data replaced, replacing the split data by a complex number 0+0i, starting with

indices

53, 129, respectively. Finally, a data symbol with a length of 256 is obtained. Next, IFFT is performed on the data symbols to obtain time domain data symbols, and then cyclic prefix is inserted, which is to eliminate inter-symbol crosstalk and multi-carrier interference. The insertion of the cyclic prefix as shown in fig. 8, 64-bit data of the tail of the data is inserted as the cyclic prefix into the head, and then 320-bit data symbols are output. After all the parallel sub-carriers finish the steps, parallel-serial conversion is carried out, parallel data are converted into serial data, and finally, the serial data are sent to a USRP sending buffer after being added with a synchronization head and are sent out. OFDM demodulation first requires positioning to the data start position using coarse and fine synchronization information. And then sequentially removing cyclic prefix, FFT, and balancing by using the inserted pilot frequency channel, and finally obtaining the data after OFDM demodulation.

Each information frame in the wireless ad hoc network has own functions, and the nodes receive different information frames and make different responses. The information frame design in the wireless ad hoc network mainly comprises a beacon frame, a network access request frame, a network access response frame, an (N) ACK response frame and a data frame (direct transmission, coordination and relay).

In this embodiment, a frame packet transmission module is described by taking a packet module of a beacon frame as an example. Beacon frame packetization module as shown in fig. 9, the information input by the beacon includes the number of network devices, the IP address in the network, and the like. And inputting the beacon information into a CRC checker for CRC calculation, and finally forming the MAC layer frame by the calculation result and the original beacon information. And inputting the partial information of the MAC layer and the destination IP address into an encapsulation physical layer vi to form a physical layer frame, splicing the partial information of the MAC layer and the destination IP address together to form a complete beacon frame, performing BPSK modulation, and sending the modulation result into an OFDM modulation vi to perform OFDM modulation transmission.

Implementation of the frame identification module as shown in fig. 10, the identification of the information frame is mainly based on the frame type field in the information frame. The receiver performs OFDM demodulation on the received signal, and analyzes the frame type and the destination IP in the header of the physical layer of the information frame. If the destination IP is the IP address of the node, corresponding processing response is carried out according to the received frame type; if the destination IP is not the node IP, the subsequent MAC layer analysis is not performed, and the data packet is directly discarded. The frame analysis module is mainly used for analyzing field information in the information frame, and takes analysis of the beacon frame as an example. When analyzing the MAC layer data, CRC verification is needed to be carried out on the data, and the next analysis can be carried out after the CRC verification is passed.

The purpose of the parsing module is to parse the beacon frame, as shown in fig. 11, firstly to determine whether the node is in the network, and secondly to obtain information of other nodes in the network. The method comprises the steps of firstly analyzing the upper limit of the devices which can be accommodated in the network, namely the total device number, then analyzing the existing device number, wherein the two information fields are used for enabling a network master node to judge whether the network can still enable other nodes to enter the network continuously. And finally, analyzing the IP address pool in the beacon frame, and sending messages to other IP addresses in the IP address pool when the network IP address pool has other IP addresses except the IP of the node.

The wireless ad hoc network communication platform built based on the USRP software radio equipment comprises a channel estimation module, a quantization module, a negotiation module and a privacy amplification module. The channel estimation module is used for carrying out channel estimation on the received detection signals to obtain channel frequency response amplitude values; the quantization module is used for quantizing the response amplitude of the channel frequency domain to obtain an initial key bit sequence; the negotiation module is used for realizing key error correction, CRC check and consistency negotiation among the communication nodes; the privacy amplification module is used for carrying out hash operation on the key bit sequence to obtain a final key.

The negotiation module comprises a main node negotiation end and each destination node negotiation end, and each negotiation end comprises an error correction module and a CRC (cyclic redundancy check) module respectively; the master node end error correction module is used for generating error correction information and sending the error correction information to each destination node end error correction module, and each destination node end error correction module performs key error correction according to the received error correction information; each destination node end checking module is used for performing CRC operation on the destination node end key after error correction, sending the generated CRC checking information to the main node end checking module, after the main node end checking module receives the CRC checking information from the destination node end, performing CRC operation on the key of the main node end, and then comparing the generated main node end CRC checking information with the received destination node end CRC checking information to obtain a checking result.

Based on the implementation of the key generation system in the wireless ad hoc network, each legal communication group generates a key comprising the following steps:

step 1: the method comprises the steps that a main node and a target node in a legal communication group alternately send detection signals in coherent time, and receive the detection signals through an antenna to perform channel estimation, wherein the main node and the target node respectively measure channel frequency domain response amplitude values; as shown in fig. 12, in this embodiment, the channel estimation is performed by using a least square method, mainly by calculating the channel state information of each subcarrier by using an interpolation method, and after obtaining the channel frequency response, performing a modulo operation on the obtained channel frequency response to obtain the amplitude of the channel frequency response as the channel characteristic parameter.

Step 2: the main node and the target node in the legal communication group respectively quantize the measured frequency domain response amplitude of the channel to obtain respective corresponding initial key bit sequences; as shown in fig. 13, in the present embodiment, the average quantization method is adopted. After the main node a and the destination node B, C, D obtain the channel frequency domain response amplitude through channel estimation respectively. Firstly, carrying out downsampling operation, then using a filter to carry out low-pass filtering, calculating the average value of the frequency response amplitude of the channel, and finally, carrying out quantization according to the obtained average value to obtain initial key bits.

Step 3: and respectively interleaving the obtained initial key bit sequence by the master node and the destination node in the legal communication group, then carrying out key error correction and CRC check by the master node and the destination node in cooperation, and finally respectively obtaining the key bit sequence with consistency after the master node and the destination node pass through consistency negotiation. In this embodiment, the performing, by the master node and the destination node, the key error correction and the CRC check includes:

(1) as shown in fig. 14, the error correction module at the main node a first performs interleaving processing on the key bits obtained by quantization, so that the bits inconsistent with both legal communication parties are uniformly distributed. The keys are then grouped, with the number of bits per group of keys being ten bits. And performing exclusive OR operation on each group of keys and the code words in the code word set respectively to obtain error correction information. Finally, the obtained error correction information packet Cheng Jiucuo frames are sent to a destination node B, C, D;

(2) the destination node B, C, D performs interleaving operation on the quantized key bits, and performs error correction on its own key after receiving a signal containing error correction information. The error correction module first performs exclusive or on the error correction information and Bob-side key bits to obtain an uncorrected codeword, as shown in fig. 15. And correcting the code word by utilizing the hamming distance minimum principle to obtain the corrected code word. And finally, obtaining the corrected secret key by using the exclusive OR of the corrected code word and the error correction information. The corrected key still has the condition of inconsistent key, so that further CRC check is needed to remove inconsistent keys. The CRC module is mainly divided into a target node B, C, D end verification module and a main node A end verification module;

(3) as shown in fig. 16, the verification module at the end of the destination node B, C, D mainly groups the corrected keys, and groups every twenty key bits into one group; performing CRC operation to obtain a CRC result of hexadecimal characters, converting the CRC result into a binary bit form, and transmitting the binary bit form to a master node A;

(4) as shown in fig. 17, after receiving the CRC check information sent by the destination node B, C, D, the master node a first performs packet CRC operation on its own local key. The generated CRC check information is then compared with the received CRC check information. Meanwhile, the set flag array represents whether the verification results are consistent. If so, transmitting 1001101001; if not, 1010110010 is sent. And finally, sending the verification result to Bob, and after Bob receives the verification information, determining whether to reserve or discard the key group according to the mark array. If the flag array is 1001101001, the key set is reserved; if the flag array is 1010110010, the key set is discarded. And finally, obtaining both legal communication parties.

Step 4: and the master node and the destination node in the legal communication group respectively carry out hash operation on the key bit sequence with consistency obtained in the step S3 to obtain a key finally used for secure encryption. In this embodiment, as shown in fig. 18, the agreed key bits obtained by negotiation are converted into hexadecimal characters, and then the packets are subjected to hash function processing, so as to finally obtain the security enhanced key.

While the invention has been described in terms of preferred embodiments, it is not intended to be limiting. Those skilled in the art will appreciate that various modifications and adaptations can be made without departing from the spirit and scope of the present invention. Accordingly, the scope of the invention is defined by the appended claims.

Claims

1. The wireless self-networking safe transmission method based on USRP is used for generating available secret keys so as to realize encryption of self-networking transmission data, and is characterized in that based on creation of 1 communication master node and at least 2 destination nodes, the communication master nodes respectively form legal communication groups with each destination node, and each legal communication group generates secret keys comprises the following steps:

s3: the master node and the destination node in the legal communication group respectively carry out interleaving treatment on the obtained initial key bit sequence, then the master node and the destination node cooperate to carry out key error correction and CRC check, and after consistency negotiation among the nodes is completed, a key bit sequence with consistency is obtained;

2. A system for implementing the USRP-based wireless ad hoc network secure transmission method of claim 1, comprising a channel estimation module, a quantization module, a negotiation module, and a privacy amplification module; the channel estimation module is used for carrying out channel estimation on the received detection signals to obtain channel frequency response amplitude values; the quantization module is used for performing quantization on the response amplitude of the channel frequency domain in the S2 to obtain an initial key bit sequence; the negotiation module is used for executing consistency negotiation between the communication nodes in the S3; the privacy amplification module is used for executing the hash operation on the key bit sequence in the S4 to obtain a final key.

3. The system for implementing the USRP-based wireless ad hoc network secure transmission method of claim 2, wherein the negotiation module includes a master node negotiation end and destination node negotiation ends, and each negotiation end includes an error correction module and a CRC check module.

4. A system for implementing a USRP-based wireless ad hoc network secure transmission method according to claim 3, wherein the master node end error correction module is used for generating error correction information and transmitting the error correction information to each destination node end error correction module, and each destination node end error correction module performs key error correction according to the received error correction information.

5. The system for implementing the USRP-based wireless ad hoc network secure transmission method of claim 3, wherein each destination node end check module is respectively configured to perform CRC operation on the error-corrected destination node end key, send the generated CRC check information to the master node end check module, and after receiving the CRC check information from the destination node end, the master node end check module performs CRC operation on the key of the master node end, and then compares the generated master node end CRC check information with the received destination node end CRC check information to obtain a check result.

6. The wireless self-organizing network safe transmission method based on the USRP according to claim 1, wherein the wireless self-organizing network safe transmission is realized by each legal communication group based on the construction of a USRP platform; the USRP platform construction comprises a programming USRP configuration module, an OFDM modulation and demodulation module, a frame identification module, a frame grouping module and a frame analysis module.