CN101795146A

CN101795146A - Multi-frequency-band cognitive network node used for frequency spectrum monitoring

Info

Publication number: CN101795146A
Application number: CN 201010121647
Authority: CN
Inventors: 吴威; 刘旭东; 苏金钊; 周忠; 赵沁平
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2010-03-10
Filing date: 2010-03-10
Publication date: 2010-08-04
Anticipated expiration: 2030-03-10
Also published as: CN101795146B

Abstract

The present invention designs a hardware terminal applied to multi-band frequency spectrum detection in wireless cognitive network, which is used to detect and utilize frequency spectrum resources in authorized TV broadcasting frequency bands and unlicensed ISM partial frequency bands. Authorized TV broadcast frequency bands are mainly concentrated in TV channels in 47MHz～910MHz VHF/UHF, and unlicensed ISM frequency bands are mainly concentrated in 433.05MHz～434.79MHz, 902～928MHz and 2.400～2.4835GHz (ZigBee) frequency bands. The hardware of the cognitive node is composed of a processor, radio frequency module, memory, display module, and power supply module; the processor adopts the ARM1136(J)FS microprocessor core of ARM Company, and is responsible for the task scheduling, information processing, driver module and Network protocol stack. The radio frequency module is divided into three parts, which are respectively responsible for scanning the TV broadcasting frequency band and the ISM frequency band. The Broadcom BCM2940 mobile TV receiver is used for the scanning of the TV broadcasting frequency band, the PTR8000+ RF module is used for scanning in the 433.05MHz～434.79MHz, 902～928MHz of the ISM frequency band, and the CC2420 RF chip is used for scanning the ZigBee frequency band. The present invention can scan the corresponding frequency bands through the above device, display the resource information of the corresponding spectrum of each frequency band, and finally realize the detection of wireless spectrum resources.

Description

The multiband cognitive network node that is used for spectrum monitoring

Technical field

The present invention relates to be used for the cognitive network node of frequency spectrum detection, more specifically, relate to the frequency spectrum detection cognitive radio, belong to the cognitive radio technology field.

Background technology

Cognition network is in cognitive radio (Cognitive Radio, development on basis CR) and come.The initial purpose that proposes of cognitive radio is to solve the not high problem of the availability of frequency spectrum that the radio spectrum resources anxiety is distributed.Under traditional spectrum management mode, the radio control department of most of country gives different users with the Frequency Distribution below the 3GHz on the one hand, and therefore along with the continuous increase of people's mobile wireless business demand, it is more and more rare that radio resource will become.And on the other hand, (Federal Communication Commissions, test report FFC) is presented at the availability of frequency spectrum from 15% to 85% of having distributed in different time and the space and does not wait by FCC.

In order to alleviate the contradiction between the low and ever-increasing frequency spectrum resource demand of the current availability of frequency spectrum, academia has proposed the notion of CR.Cognitive radio realizes that by frequency spectrum environment such as perceived frequency, time and spatial domains frequency spectrum is dynamically shared, and spectrum utilization flexibly is provided, and utilizes the frequency spectrum that leaves unused to carry out the signal transmission, to satisfy commerce, military, the continuous demand that changes of government guest.The research of CR at present is at the early-stage, and a lot of viewpoints are also ununified, even dispute is very big, and for example authorized user is suspected the reliability of CR user's frequency spectrum detection, worries that communication reliability is subjected to CR user's threat; The various frequency spectrum detecting methods that propose at present the system in reality of often the having no chance checking of getting on the other hand.Therefore, a concrete experimental system can well illustrate and verify the problems of CR, can accumulate experience, provide reference to the establishment of CR Study on Theory and standard.

Comparatively popular and ripe Software Radio platform is common software radio peripheral hardware (the Universal Software Radio Peripheral that Eric Blossom proposes in the GUN Radio and the Ettus Matt of proposition in 2000 at present, USRP), GUNRadio is a software kit that is used to make up Software Radio platform of increasing income, be responsible for the digital signal that receives from hardware platform USRP is handled, the data after will handling are then passed to the external world by display or the sound card of PC.USRP comprises a mother matrix and some daughter boards, and mother matrix is responsible for being transferred among the PC changing finally from the live signal of daughter board or IQ signal.It can be changed daughter board and realize scanning to different frequency range, but can not scan a plurality of frequency ranges simultaneously, and the present invention can scan three frequency ranges simultaneously, utilizes frequency spectrum resource more fully.

Summary of the invention

The objective of the invention is to realize a kind of cognitive network node that is used for frequency spectrum detection, the operating position of its frequency spectrum resource in can the certain frequency range of perception.By three different frequency ranges are monitored, fully also effectively utilize existing frequency spectrum resource.

The technical solution used in the present invention is:

The cognitive network node that is used for frequency spectrum detection, it is characterized in that, the hardware of this node is made up of processor, radio-frequency module, memory, display module and power module, and radio-frequency module, memory, display module link to each other with processor, and power module provides power supply for other each module.

The ARM1136J of processor adopting ARM company (F)-S micro-processor kernel cooperates suitable peripheral circuit, erects the hardware platform of whole node.I/O pin by processor can be realized common hardware standard interfaces such as RS232, SPI and USB, also can realize simultaneously the driver of its hardware interface by processor, the reading and writing data program can be carried out the scanning of corresponding frequency spectrum after making radio-frequency apparatus insert cognitive nodes immediately.

Radio-frequency module mainly is responsible for three frequency ranges are carried out perception and transmission:

1.47MHz the perception and the transmission of the TV channel the in～910MHzVHF/UHF frequency range

Send for signal, will realize the transmission system of DVB-H transmission IP service by cognitive nodes.By microprocessor the data that perceive being carried out certain encapsulation launches then.

Receive for signal, adopt television broadcast receiver to receive the digital television signal of terrestrial broadcasting and satellite broadcasting.The present invention utilizes hardware mode to realize DVB-H MPE-FEC mechanism for correcting errors, the data that mis repair and reduction send.Adopt the mobile TV receiver of Broadcom BCM2940.

2.433.05 the perception of～434.79MHz and 902～928MHz ISM band and transmission

The nRF905 monolithic radio frequency transceiving chip of selecting for use Norway Nordic VLSI company to produce.It can work in three ISM of 433/868/915MHz (industry, science and medical science) frequency range, and can perception and the spectrum information of surveying on the corresponding band.

3.2.400 the perception and the transmission of～2.4835GHz ISM band (ZigBee)

Selection work is at the single-chip low-voltage CC2420 of 2.4GHz transceiver.CC2420 be TI-Chipcon company release first meet the radio-frequency (RF) transceiver of 2.4GHz IEEE802.15.4 standard, also be the RF device that first item is applicable to the ZigBee product.

Compared with prior art, beneficial effect of the present invention is:

Traditional Wireless Telecom Equipment can only use pre-assigned definite frequency range usually, and its hardware is only supported less frequency band range, and can only be with fixing bandwidth work.Cognitive nodes device of the present invention can be selected working frequency range in three different band limits, in conjunction with concrete algorithm, the existence and the appearance of concrete analysis radio frequency environment, judgement authorized user (as TV user), and adjust parameter, take rationally to dodge strategy according to analysis result, and authorized user original on its frequency range is not caused flagrant influence.

Description of drawings

Fig. 1 is the hardware architecture framework of cognitive nodes;

Fig. 2 is ARM1136J (F)-S micro-processor kernel framework;

Fig. 3 is a DVB-H data encapsulation form;

Fig. 4 is that cognitive nodes is used schematic diagram;

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing.

The overall construction drawing of its hardware as shown in Figure 1, sensor node is made up of the processor shown in the figure, radio-frequency module, display module and power module.Radio-frequency module, memory, display module and processor link to each other, and power module provides power supply for each module.

It is the microprocessor of kernel that the processor chips of sensor node are selected for use with the ARM1136J of ARM company (F)-S, ARM1136J (F)-S kernel is based on the ARMv6 instruction set architecture, adopt the operation of 8 level production lines, Load-Store unit and arithmetic operation unit have independently streamline respectively, and have branch prediction and forward data passage, can improve the efficient of pile line operation efficiently.In the system of ARMv6, between processor cores, instruction Cache and the Data Cache, and the data channel between kernel and the coprocessor is 64bit, permission is in two instructions of single cycle emission, improve the transfer rate of data greatly, avoided simultaneously the power consumption that 64 bit processors are brought and the rising significantly of cost again.The instruction set of ARMv6 has increased the multimedia instruction of a large amount of supports, makes ARM11 be suitable for Voice ﹠ Video signal processing and 3-D view signal processing, and the MMU of ARM11 can support the zero access of memory.ARM1136J (F)-S kernel highest frequency can reach 660MHz, so disposal ability is very powerful.The I/O pin and the peripheral circuit of design microprocessor are realized common hardware standard interfaces such as USB, RS232, and realize the driver and the reading and writing data program of its interface, just can expand ancillary equipment more easily by these interfaces.

The radio-frequency module of sensor node is divided into the perception of three frequency ranges and transmission:

Send for signal, will realize the transmission system of DVB-H transmission IP service by cognitive nodes.At first the service data of DVB-H is packaged into after the IP package in processor, it is packaged among the transmission stream TS again, and add timesharing section (Time-Slicing) information simultaneously, modulation becomes wireless signal to send again.Wherein many agreements encapsulation MPE (Multi-Protocol Encapsulation) of transmitting terminal, reach an agreement on packaging forward error correction mechanism MPE-FEC and Time-Slicing mechanism will be comprised among encapsulation of IP package and the crossfire TS more.Its data encapsulation form as shown in Figure 3.

Receive for signal, adopt television broadcast receiver to receive the digital television signal of terrestrial broadcasting and satellite broadcasting.Need after the receiving terminal received signal to carry out reverse error-correcting decoding action, obtain and repair the error in data that is taken place because of transmission.(Multi-Protocol Encapsulation, MPE) during form, the present invention utilizes hardware mode to realize DVB-H MPE-FEC mechanism for correcting errors, the data that mis repair and reduction send decomposing the multi-protocols encapsulation.Adopt the mobile TV receiver of USB 2.0 high-speed interfaces of BroadcomBCM2940.The BCM2940 of Broadcom company is a monolithic reception of Mobile Digital TV scheme, is applicable to two kinds of standards of DVB-T and DVB-H, therefore is responsible for the spectrum signal of receiving television broadcasting frequency range with this receiver, gives processor after the parsing and handles.

The nRF905 monolithic radio frequency transceiving chip that the Norway Nordic VLSI company that selects for use produces, it can work in three ISM of 433/868/915MHz (industry, science and medical science) frequency range, have a plurality of channels (maximum more than 170), the special occasions of the multichannel work of satisfying the demand especially.Change-over time between the channel is less than 650us.NRF905 is made up of frequency synthesizer, receiving demodulation device, power amplifier, crystal oscillator and modulator, need not add filter.The ShockBurstTM mode of operation is handled prefix and CRC (CRC) automatically, uses SPI interface and micro-controller communications.Microprocessor is by carrying out frequency spectrum perception and transmission to this chip programming control in its available frequency band.

3.2.400 the perception and the transmission of～2.4835GHz ISM band (ZigBee)

Selection work is at the single-chip low-voltage CC2420 of 2.4GHz transceiver.CC2420 be TI-Chipcon company release first meet the radio-frequency (RF) transceiver of 2.4GHz IEEE802.15.4 standard, also be the RF device that first item is applicable to the ZigBee product.It is made with 0.18 μ m CMOS technology based on the SmartRF03 technology of Chipcon company, only needs few external devices, and stable performance and power consumption are extremely low.Utilize the Wireless Telecom Equipment of this chip development to support message transmission rate, can realize multi-multipoint quickly networking up to 250kb/s.Just can control its perception of in corresponding frequency range, carrying out frequency spectrum and send by the driving that in microprocessor, realizes it.

The whole software structure of cognitive nodes mainly is made up of network protocol stack, standard interface driving, radio-frequency module driving, information processing and the several modules of upper layer application interrelated logic as shown in Figure 2.Wherein network protocol stack is made up of agreements such as physical layer, media access control layer, network layer, transmission controls.

Physical layer is responsible for finishing Radio Link and can be connected, and guarantees that original data can finish transmission on physical medium; The major function of medium Access Layer is to judge currently whether can send data to physical layer, need add control information to data message if can send, the form stipulated of data and control information sends to physical layer the most at last, the MAC agreement is at first judged the information of input and whether error of transmission is taken place when receiving data, if there is not mistake, then removes control information and be sent to the upper strata; The major function of network layer is that according to the wireless sensor network topology information that gets access to, the generation routing table is transmitted message according to destination address and local routing table after receiving message, finishes the point-to-point reliable transmission; Transmission control layer adds necessary header with data message, comprises control information transmissions such as source address, destination address, sequence of message number, confirmation message sequence number, guarantees reliable transmission end to end.

Be driver layer on network protocol stack, the corresponding driver module of each interface is finished the operations such as read-write to this interface, so that from corresponding radio-frequency module reading of data.

The information exchange processing layer is responsible for from each standard interface reading of data data being carried out format conversion, and the data that a plurality of radio-frequency modules transmit are handled, and afterwards the data upload of handling well is further handled to application layer.

Fig. 4 is that of cognitive nodes uses schematic diagram, it has mainly illustrated the applied environment of the cognitive nodes of this invention, cognitive nodes among the figure can be carried out perception to three frequency ranges in the ambient network by its radio-frequency module and be detected, give microprocessor with the data of perception and handle, be controlled at wherein certain frequency range by microprocessor then and carry out work.Two cognitive nodes in environment adjacent also can communicate mutual cooperation and finish perception simultaneously.

Separate statement:

The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims

1. A cognitive network node for spectrum detection, its characteristics include the following aspects:

1) The hardware of the cognitive network node is composed of a microprocessor, a radio frequency module, a memory, a display module and a power module. The radio frequency module, memory and display module are connected to the microprocessor, and the power module provides power for other modules; the radio frequency module belongs to The slave device of the microprocessor, its signal reception and transmission are managed by the microprocessor, and it is transmitted with the microprocessor through SPI; the execution part of the microprocessor includes task scheduling, information processing, and network protocol stack, each driver The module corresponds to the driver program of a radio frequency module. The microprocessor is responsible for task scheduling among the radio frequency module, display module, memory and power supply module. The radio frequency module hands over the obtained spectrum information to the microprocessor for information processing. The network protocol stack is responsible for Each radio frequency module sends data first, and sends the processed data to the microprocessor;

2) The radio frequency module is responsible for scanning spectrum resources and occupying available spectrum resources, which includes scanning three frequency bands:

2.1) Authorized TV broadcast frequency band, TV channel in 47MHz～910MhzVHF/UHF

2.2) Unlicensed ISM frequency band, 433.05MHz～434.79MHz, 902～928MHz

2.3) Unauthorized ISM frequency band, 2.400～2.4835GHz, namely ZigBee

3) The microprocessor on the cognitive node analyzes the information scanned by each frequency band, records the results, and feeds back to the user;

4) For the scannable frequency band, the cognitive node has the function of occupying this frequency band, and can switch between different frequency bands and their channels;

5) Cognitive nodes have universal interfaces USB and RS232, and can be extended to other frequency bands through other devices with the above-mentioned interfaces.

2. The cognitive network node for spectrum detection as claimed in claim 1, characterized in that:

1) The microprocessor and the radio frequency module are connected through a serial synchronous communication protocol (SPI) to complete data exchange;

2) The radio frequency module includes the following three parts:

2.1) Broadcom BCM2940 mobile TV receiver is used to monitor the spectrum resources of TV channels;

2.2) The PTR8000+ radio frequency module is used to monitor the spectrum resources of the unlicensed ISM frequency band, and its frequency range is 433.05MHz～434.79MHz, 902～928MHz;

2.3) The CC2420 radio frequency module is used to monitor the spectrum resources of the unlicensed ISM frequency band, and its frequency range is 2.400～2.4835GHz;

3) The microprocessor is responsible for controlling each radio frequency module, and periodically controls three frequency bands: authorized TV broadcasting frequency band 47MHz～910Mhz, unlicensed ISM frequency band 433.05MHz～434.79MHz, 902～928MHz, unlicensed ISM frequency band 2.400～2.4835 GHz to scan;

4) In the microprocessor, the hardware interface USB, RS232 driver, data reading and writing program are realized, so that the corresponding spectrum can be scanned immediately after the extended radio frequency device is connected to the cognitive node;

5) For the transmission of signals in the TV broadcast frequency band, the cognitive node implements a transmission system that applies the DVB-H standard to transmit IP services;

6) The cognitive node has the function of displaying the spectrum information of each frequency band through the liquid crystal screen in the display module.

3. The cognitive network node for spectrum detection as claimed in claim 2, characterized in that:

1) Monitoring of three working frequency bands: authorized TV broadcasting frequency band 47MHz～910Mhz, unlicensed ISM frequency band 433.05MHz～434.79MHz, 902～928MHz, and unlicensed ISM frequency band 2.400～2.4835GHz mainly includes the following aspects:

1.1) By performing energy measurements on all channels in the three frequency bands, an available channel table for the three frequency bands is generated, including the number of available channels in each frequency band, channel evaluation, and channel abandonment reasons;

1.2) Periodically execute step 1.1 to update the available channel table until the system stops working;

1.3) The microprocessor updates the display module at a certain period, and feeds back the information of the available channel list to the user;

2) The transmission system for DVB-H transmission of IP services mainly includes the following aspects:

2.1) Encapsulating DVB-H service data into IP packets;

2.2) Encapsulate the IP encapsulation packet in the transport stream TS, and add time-slicing (Time-Slicing) information at the same time;

2.3) Modulate the transport stream TS into a wireless signal and transmit it.