With the continuous development of society, wireless network technology has been greatly improved. Let's take a look at the papers on wireless network technology, hoping to help everyone!
The application of Bluetooth in wireless access is discussed, and the single chip Bluetooth product BlueCoreTM0 1 of CSR(CambridgeSiliconRadio) is briefly introduced.
Keywords: Bluetooth; Wireless communication; Data; A common old telephone system
Bluetooth solution wireless connection
This paper introduces the application of Bluetooth in wireless connection, and briefly introduces the Bluetooth MCU of CSR-Bluetooth 0 1.
Keywords: Bluetooth; Wireless communication; Data; A common old telephone system
1 Introduction
Bluetooth technology is a new wireless communication technology that uses microwave wireless communication technology to complete point-to-point or point-to-multipoint short-distance communication instead of data line. Using Bluetooth, devices that need data and voice communication can be connected into a piconet (piconet), or several piconets can be further interconnected to form a larger scatternet network (distributed network). The PSTN wireless access point of Bluetooth uses the existing VoIP phone as the carrier to predict its development. He enables mobile phone users to realize signal connection through fixed telephone network, so that the majority of mobile phone users can become users of fixed telephone network at the same time. For mobile phone users, while solving the problem of mobile phone network signal, it can also reduce the communication cost of mobile phone users; For fixed telephone operators, it means huge telephone revenue. There are several innovations in this scheme:
(1) instead of a large number of cables for short-distance connection, especially in places where cables can't reach, Bluetooth has greater advantages.
(2) The computer can surf the Internet wirelessly through the Bluetooth PSTN wireless access point and enjoy the network resources at the same time.
(3) The cross-profile application protocol stack of bluetooth profile is realized, which enables the bluetooth PSTN wireless access point to communicate internally with all Bluetooth mobile phones in the network.
(4) Because the scheme design is designed according to the Bluetooth technical standard, it is compatible with Bluetooth products such as Bluetooth mobile phones and adapters.
Introduction of 2BC0 1 Chip and Development Tool Bluelab
BC0 1(BlueCore0 1) is a single-chip Bluetooth product designed by CSR(CambridgeSiliconRadio). It integrates wireless devices, microprocessor and baseband circuit, adopts 0.35μm standard CMOS process, and can provide fully compatible data and voice communication through external FlashROM with Bluetooth protocol. After optimized design, only a few external RF components are needed, so the motherboard can be designed quickly. Therefore, the shortest time to market can be achieved at the lowest cost.
Its main features are as follows:
(1) conforms to the Bluetooth V 1. 1+0 specification.
(2) Main interface with USB and UART.
(3) Programmable PCM interface supports bidirectional serial synchronous voice transmission of 13b 8kss- 1.
(4) Built-in digitizer can convert linear PCM (pulse code modulation), A-law PCM, μ-law PCM and CVSD (continuous slope increment modulation) and decode Bluetooth control protocol to HCI layer.
(5) Adopt a single power supply of 3. 15V, and support various power saving modes such as PART, SNIFF and HOLD.
(6) piconet supporting all packet types and up to 7 slave devices.
(7) The chip includes link control, link management, HCI and optional L2CAP, RFCOMM and SDP multi-layer software protocol stacks, which can be used directly.
(8) Provide virtual machine mechanism. RISC microprocessor embedded with 16b can run the user program downloaded to FlashROM while running the protocol stack, thus realizing a real single chip.
Its structural block diagram is shown in figure 1.
Bluelab is a simulation development system specially designed for Bluecore. It simulates the environment of Bluecore0 1 on PC, thus facilitating the development of applications based on Bluecore0 1. It includes compiler, emulator/debugger, documentation and some source code samples. Bluelab also provides Bluestack, a Bluetooth protocol stack that supports high-level protocols such as SDP, L2CAP and RFCOMM. Users can call Bluestack through UART/USB interface or access Bluestack through VM.
3 system scheme design
The whole system consists of two parts: front-end data processing and PC-side data management. The front-end data processing block diagram is shown in Figure 2.
The air wireless interface of Bluetooth ISDN access point is Bluetooth, the wired interface is RJ 1 1, the S/T interface of ISDN and the USB data interface. The S-port transceiver can provide the functions required by CCITT's recommendation I.430 on ISDNS/T reference point, and support full-duplex data transceiver in the 4-wire balanced transmission mode of192kb/s/s. Due to the limited internal resources and pins of BC0 1, MCU 80C 196 mainly controls and coordinates the work of each module. It deals with D-channel signaling, B-channel data transceiver and external interrupt applications, and mainly provides digital-to-analog conversion of voice signals and A-law/μ-law compression PCM coding and decoding through various SLIC modules, which has the function of generating and controlling various signal tones. The Bluetooth module mainly realizes the Bluetooth function and provides an air interface in line with bluetooth profile. It integrates various Bluetooth protocols (including CTP application protocol stack and internal telephone application protocol stack) and management programs.
In order to form the network management of Bluetooth piconet, the data management of PC is the master device of piconet, and the data processing of front end is the slave device. The overall system structure is shown in Figure 3.
BC0 1 connected to the PC is the master device, and it will automatically search for Bluetooth devices within the query range and add them to the piconet as slaves. Because each slave device has a unique BD _ Addr (Bluetooth device address), the master device can distinguish each slave device and control it.
4 software structure
The software design is based on L2CAP layer, and the function of the slave station is to accept the query and connection request of the master station, or to join the piconet after querying the existing piconet. The slave function is simple, and all the program codes can be run in FlashROM of single chip microcomputer 80C 196. The master node is responsible for managing the entire piconet, controlling and managing each slave node, so the resources provided by BC0 1 can no longer be satisfied. Therefore, the software above L2CAP protocol layer runs on PC, and the interface with PC is HCI layer. The software structure is shown in Figure 4.
5 conclusion
In the field application of wireless access, the distance between the central control node and each wireless access is within1000 mm. At present, the coverage of high-power Bluetooth chip can reach1000 m, which fully meets the practical application. The online debugging of the scheme has been completed in the laboratory, which meets the preliminary design requirements. The next step is to apply the scheme to the actual wireless access site, conduct on-site debugging and further improve the system.
refer to
[1] Jin Chun, Xu,. Bluetooth technology [M]. Beijing: Beijing Electronic Industry Press, 200 1.
[2] Bluetooth system version specification 1. 1a. 26 July, 1999.
[3] Xu Aijun. Programming and Application of Advanced Single Chip Microcomputer Language C5 1Windows [M]. Beijing: Electronic Industry Press, 200 1.
[4] Krulinskidj。 Technical insider of programming Microsoft Visual C++6.0 [M]. Beijing: Hope Electronic Publishing House, 1999.
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