As an application-oriented research field, wireless networks have achieved rapid development in recent years. In the research and development of key technologies, the academic community has carried out a lot of research from network protocols, data fusion, test and measurement, operating system, service quality, node positioning, time synchronization, etc., and achieved fruitful results; the industry is also in environmental monitoring, military Application exploration in target tracking, smart home, automatic meter reading, lighting control, building health monitoring, power line monitoring and other fields. With the promotion of applications, wireless sensor network technology has begun to expose more and more problems. Devices from different vendors need to achieve interoperability and avoid mutual interference with the current system. Therefore, different chip manufacturers, solution providers, product providers and associated device providers are required to reach a certain tacit agreement and work together to achieve the goal. This is the background to the standardization of wireless sensor networks. In fact, because the standardization work is related to many economic interests and even social interests, it is often valued by the relevant industries. How to coordinate the interests of all parties and reach a consensus requires the participants to have sufficient understanding and patience.
So far, the standardization work of wireless sensor networks has received widespread attention from many national and international standards organizations, and a series of drafts and even standard specifications have been completed. The most famous of these is the IEEE 802.15.4/zigbee specification, which has even been considered a standard by some researchers and industry. IEEE 802.15.4 defines the physical layer and link layer specifications for short-range wireless communications, and zigbee defines network interconnection, transport, and application specifications. Although the IEEE802.15.4 and zigbee protocols have been introduced for many years, with the promotion of the application and the development of the industry, the basic protocol content can not fully meet the needs, and the protocol only defines the content of the network communication, there is no sensor component. The standard protocol interface is proposed, so it is difficult to carry the dream and mission of wireless sensor network technology. In addition, when the standard is in different countries, it is bound to be bound by the current standards in the country. To this end, people began to introduce more versions based on the IEEE 802.15.4/zigbee protocol to adapt to different applications, different countries and regions.
Despite the imperfections, IEEE 802.15.4/zigbee is still the best combination of the industry's development of wireless sensor network technology. This article will focus on the IEEE 802.15.4/zigbee protocol specification, with due regard to other relevant standards of sensor network technology. Of course, the standardization of wireless sensor networks has a long way to go: First, wireless sensor networks are still an emerging field, and their research and applications are still quite young, and the demand for the industry is still unclear. Second, IEEE 802.15/zigbee is not aimed at wireless. The sensor network is tailor-made, and some problems need to be further solved in the wireless sensor network environment. In addition, the international standardization work for the wireless sensor network technology has just begun, and the domestic standardization working group has just been established. To this end, we must be fully prepared for the smooth completion of the standardization work.
1. PHY/MAC layer standard
The underlying standards for wireless sensor networks generally follow the relevant standard portion of the wireless personal area network (IEEE 802.15). The Wireless Personal Area Network (WPAN) appears earlier than the sensor network and is usually defined as a wireless short-range private network that provides interconnection between personal and consumer electronic devices. The wireless personal area network focuses on the two-way communication technology problem between portable mobile devices (such as personal computers, peripheral devices, PDAs, mobile phones, digital products and other consumer electronic devices), and its typical coverage is generally within 10 meters. The IEEE 802.15 working group was specifically set up to accomplish this mission and has completed the development of a series of related standards, including the underlying standard IEEE 802.15.4, which is widely used in sensor networks.
(1) IEEE 802.15.4b specification
The IEEE 802.15.4 standard is mainly developed for the Low-Rate Wireless Personal Area Network (LR-WPAN). The standard targets low energy consumption, low-rate transmission, and low cost (which is consistent with wireless sensor networks) and is designed to provide a unified interface for low-speed interconnection between different devices within an individual or home range. Since the characteristics of the LR-WPAN network defined by IEEE 802.15.4 and the intra-cluster communication of the wireless sensor network have many similarities, many research institutions regard it as the physical and link layer communication standard of the sensor network node.
The IEEE 802.15.4 standard defines the physical layer and media access control sublayers, in line with the Open Systems Interconnection Model (OSI). The physical layer includes a radio frequency transceiver and an underlying control module, and the medium access control sublayer provides a service interface for the upper layer to access the physical channel. Figure 1 shows the relationship between IEEE 802.15.4 layers and layers and the IEEE 802.15.4/zigbee protocol architecture.
IEEE 802.15.4 is designed for low-cost and higher-level integration in the physical (PHY) layer design. The operating frequency is divided into three types: 868MHz, 915MHz and 2.4GHz. The channels that can be used in each frequency band are 1 respectively. One, ten, and sixteen each providing a transmission rate of 20 kb/s, 40 kb/s, and 250 kb/s, and the transmission range is between 10 meters and 100 meters. The three frequency bands used in the specification are the open bands of ISM (Industrial Scientific and Medical) for scientific research and medical treatment defined by the ITU Telecommunication Standardization Sector (ITUT), and are widely used by various wireless communication systems. In order to reduce inter-system interference, the protocol specifies direct sequence spread spectrum (DSSS) coding techniques in each frequency band. Compared with other digital coding methods, direct sequence spread spectrum technology can make the analog circuit design of the physical layer simple and has higher fault tolerance performance, which is suitable for the implementation of low-end systems.
IEEE 802.15.4 defines two access modes for the medium access control layer. One is Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). In this way, referring to the DCF mode defined by the IEEE802.11 standard in the wireless local area network (WLAN), it is easy to achieve channel level coexistence with a wireless local area network (WLAN, Wireless LAN). The so-called CSMA/CA is to listen to whether there is a co-channel carrier in the medium before transmission. If it does not exist, it means that the channel is idle and will enter the data transmission state directly; if there is carrier, it will be randomly evacuated. The channel is re-detected after a period of time. This medium access control layer scheme simplifies the process of implementing self-organizing (Ad Hoc) network applications, but it brings troubles to improve bandwidth utilization in high-traffic transmission applications. At the same time, because there is no power management design, it is implemented. Low-power network applications based on sleep mechanisms require more work.
Another communication mode defined by IEEE 802.15.4 is similar to the PCF mode defined by the 802.11 standard. It is easy to achieve low by using a synchronized superframe mechanism to improve channel utilization and by defining a sleep period in a superframe. Power control. The PCF mode defines two devices: a Full-Function Device (FFD) and a Reduced-Function Device (RFD). The FFD device supports all 49 basic parameters, while the RFD device requires only 38 basic parameters for its minimum configuration. In the PCF mode, the FFD device acts as a coordinator to control the synchronization and data transceiving processes of all associated RFD devices, and can communicate with any device in the network. The RFD device can only interwork with the FFD device associated with it. In PCF mode, there is at least one FFD device in the IEEE 802.15.4 network as the PAN Coordinator, which acts as the network master controller, and performs inter-cluster and intra-cluster synchronization, packet forwarding, and network establishment. , member management and other tasks.
The IEEE 802.15.4 standard supports both star and peer-to-peer network topologies, with 16-bit and 64-bit address formats. The 64-bit address is the only extended address in the world, and the 16-bit segment address is used for small network construction or as the identification address of the device in the cluster. The IEEE 802.15.4b standard has several variants, including IEEE 802.15.4a for low-speed ultra-wideband, and IEEE 802.15.4c and IEEE 802.15.4e, which are currently being promoted in China, and major advances in Japan. The IEEE 802.15.4d is not discussed in depth here.
(2) Bluetooth technology
In May 1998, just after the establishment of the IEEE 802.15 wireless personal area network working group, five world-renowned IT companies: Ericsson, IBM, Intel, Nokia and Toshiba A research and development program called "Bluetooth" was announced. In July 1999, the Bluetooth Working Group introduced the Bluetooth protocol version 1.0, which was updated to version 1.1 in 2001, which is known as the IEEE 802.15.1 protocol. The agreement is designed to design a common international standard for the Radio Air Interface and its software, enabling the further integration of communications and computers, enabling portable devices from different manufacturers to achieve close-range interoperability without cables. ability. As soon as the plan was announced, it received extensive support from nearly 2,000 vendors including Motorola, Lucent, Compaq, Simens, 3Com, TDK and Microsoft. And adoption.
Bluetooth technology also works in the 2.4GHz ISM band. It uses fast frequency hopping and short packet technology to reduce co-channel interference, ensure the reliability and security of physical layer transmission, has certain networking capabilities, and supports 64Kbps real-time voice. Bluetooth technology is becoming more and more popular, and related products in the market are also increasing. However, with the emergence of ultra-wideband technology, wireless LAN and zigbee technology, especially its security, price, power consumption and other issues are increasingly apparent, and its competitive advantage. begin descending. In 2004, the Bluetooth working group launched version 2.0, which tripled the bandwidth and reduced power consumption by half, rebuilding the confidence of the industry to a certain extent.
Because of the commonality between Bluetooth technology and zigbee technology, they are often used in wireless sensor networks.
2. Other wireless personal area network standards
The wireless sensor network needs to build a complete network from the physical layer to the application layer, and the wireless personal area network standard prescribes the physical layer and medium access control layer specifications. In addition to the IEEE 802.15.4 and Bluetooth technologies discussed above, the wireless personal area network technology solution also includes: ultra-wideband (UWB) technology, infrared (IrDA) technology, home radio frequency (HomeRF) technology, etc., and their common features are Short-range, low-power, low-cost, personal-specific, etc., which are used in the underlying protocol scheme of wireless sensor networks in different application scenarios, which are briefly described as follows:
(1) Ultra-wideband (UWB) technology
Ultra Wide-Band (UWB) technology originated in the late 1950s and is a technology that uses broadband electric wave signals from a few Hz to several GHz. It emits a very short pulse and receives and analyzes the reflected back. Signal, you can get the information of the detected object. UWB uses a very high bandwidth, so its power spectral density is very flat, showing that the output power at any frequency is very small, even lower than the noise emitted by ordinary equipment, so it has good anti-interference and security. Sex. Ultra-wideband technology was originally used primarily as a military technology in radar detection and location applications. The US FCC (Federal Communications Commission) granted the technology to the civilian sector in February 2002. In addition to low power consumption, the transmission rate of ultra-wideband technology can easily reach more than 100Mbps, and its second-generation products are expected to reach more than 500Mbps. Only this one indicator can make many other technologies far behind. The standard dispute surrounding UWB has been fierce since the beginning. Freescale's DS-UWB and MBOA advocated by TI have gradually emerged. In recent years, domestic research in this area has also been very popular.
Due to its low power consumption, high bandwidth and strong anti-interference ability, UWB technology has undoubtedly a fantastic development prospect, but UWB chip products have not been available for a long time, which undoubtedly leaves us with a big regret. In recent years, reports on related products have begun to appear, but this deep-rooted technology also needs to be promoted by the entire industry. At present, the ultra-wideband technology can be said to be the first to show its edge. It is believed that it belongs to the type of late, old and strong, and it will have a lot to do in wireless sensor network applications.
(2) Infrared (IrDA) technology
Infrared technology is a technology for point-to-point communication using infrared rays. It was promoted by the IrDA (Infrared Data Association), a non-profit organization of the Infrared Data Standards Association established in 1993. The association is committed to establishing a world standard for wireless communication connections. Currently has more than 130 official corporate members. The transmission rate of infrared technology has increased from 4 Mbps of the initial FIR to 16 Mbps of the current VFIR, and the reception angle has also been extended from the original 30 to 120. Since it is only used for point-to-point communication and has a certain directionality, data transmission is less subject to interference. Due to its small size, low cost, low power consumption, and no need for frequency application, infrared technology has been widely used since its birth. It is an evergreen tree in the field of wireless personal area networks. After years of development, its hardware and supporting software technology are quite mature. At present, there are at least 50 million devices in the world using IrDA technology, and still growing at an annual rate of 50%. Today, 95% of laptops are equipped with an IrDA interface, while remote control devices (television, air conditioners, digital products, etc.) are more commonly used in infrared technology.
However, IrDA is a line-of-sight transmission technology. The core components of infrared LEDs are not very durable, and it is impossible to build a stable network for long-term operation. As a result, infrared technology has not become the physical layer standard technology of wireless personal area networks. Attempts have been made in wireless sensor network applications (such as location tracking) and are used in conjunction with other wireless technologies.
(3) Home RF (HomeRF) technology
The Home Radio Frequency Working Group (HomeRF WG) was established in March 1998 and is led by the US Home RF Committee. The first members include: Intel, IBM, Compaq, 3Com, Philips, Microsoft. Companies such as Motorola, whose main purpose is to build interoperable voice and data networks in the home, while consumers can afford it. The Home Radio Frequency Working Group developed the Shared Wireless Access Protocol (SAP) in 1998, which is aimed at home wireless LANs. The data communication of the protocol adopts the simplified IEEE 802.11 protocol standard, and uses Ethernet carrier sense multiple access/collision detection (CSMA/CD) technology; its voice communication adopts DECT (Digital Enhanced Cordless Telephony) standard, and the time is divided. Multiple Access (TDMA) technology. The home RF operating frequency band is 2.4 GHz, initially supporting data and audio maximum data transmission rate of 2 Mbps, in the new home radio frequency 2. The WBFH (Wide Band Frequency Hopping) technology is adopted in the standard to increase the frequency hopping modulation function. The peak data bandwidth can reach 10 Mbps, which can satisfy most applications.
The penetration rate of household radio frequency technology reached 45% at around 2000, but because the technical standards were controlled by dozens of companies, they were not as open as infrared technology, especially the emergence of the 802.11b standard. Since 2001, home The penetration rate of radio frequency suddenly dropped to 30%. In 2003, the home RF working group announced that it would stop research and development and promotion. The once-popular home radio has finally withdrawn from the historical stage of the wireless personal area network, just like a short-lived.
3. Routing and high-level standards
Based on the underlying standards discussed above, some high-level protocol standards including routing and application layers have emerged, including zigbee/IEEE 802.15.4, 6LowPAN, and IEEE1451.5 (Wireless Sensing Communication Interface Standard). In addition, Z-Wave Alliance, Cypress (Wireless USB Sensor Network) and other similar standards have been introduced, but before the standards specifically designed for wireless sensor networks came out, zigbee is undoubtedly the most favored and also more Many app manufacturers are highly respected, here is a brief introduction.
(1) zigbee protocol specification
The zigbee alliance was founded in August 2001. Its original members include: Honeywell, Invensys, Mitsubishi (MITSUBISHI), Motorola and Philips, and currently has more than 200 members. The zigbee 1.0 (Revision 7) specification was officially launched in December 2004. In December 2006, zigbee 2006 (Revision 13), version 1.1, was launched. In 2007, zigbee 2007 Pro was launched. In spring 2008, There are certain updates. Zigbee technology has many advantages such as low power consumption, low cost, large network capacity, short delay, safe and reliable, flexible working frequency, etc. It is currently a popular wireless personal area network solution, and is also regarded by many as a wireless sensor network. The de facto standard.
The zigbee alliance standardizes network layer protocols and Application Programming Interfaces (APIs). The zigbee protocol stack architecture is based on a seven-layer model of the Open Systems Interconnection model, including the IEEE 802.15.4 standard and network layer and application layer protocols defined independently by the Alliance. The network layer defined by zigbee is mainly responsible for the construction and maintenance of the network topology, as well as device addressing and routing. It belongs to the general network layer function category. The application layer includes the Aplication Support Sub-layer (APS) and the zigbee device. The object (zigbee Device Object, ZDO) and the device-customized application component are responsible for the aggregation of service data flows, device discovery, service discovery, security and authentication.
In addition, the zigbee alliance is also responsible for the development of interoperability testing and certification specifications for zigbee products. The zigbee alliance regularly organizes ZigFest events, allowing manufacturers of zigbee products to have an open communication opportunity to complete interoperability testing of devices. In the certification part, the zigbee alliance defines three levels of certification: Level 1 It is the authentication physical layer and the medium access control layer, which has the most direct relationship with the chip factory; the second level (Level 2) is the authentication zigbee protocol stack (Stack), also known as the zigbee compatible platform certification (Compliant Platform Certification); Level 3 is a certified zigbee product. A third-level certified product is allowed to be tagged with zigbee, so it is also called zigbee logo certification.
The protocol chip is the carrier of the protocol standard and is the most easily reflected form of intellectual property. There are many zigbee chip products and solutions on the market, including Jennic's JN5121/JN5139, Chipcon's CC2430/CC2431 (acquired by TI) and Freescale MC13192, Ember's EM250 zigbee and other development tools. And the chip, Table 1 compares these chip indicators.
(2) IEEE 1451.5 standard
In addition to the above two general specifications, specific standards for specific industries, such as electric power, industrial control, consumer electronics, and smart home, are also being developed in different application areas of wireless sensor networks. Here is a brief discussion of IEEE1451 in the field of industrial control. X, of course, the industrial standards are complicated. Recently, the wireless technology standard ISA SP100 for industrial automation applications is being developed. Many Chinese industrial and academic colleagues have worked hard to participate in the development of this standard.
The IEEE1451 family of standards is designed to enable industrial transmitters (sensors + actuators) to be independent of the communication network and connected to existing microprocessor systems, instrumentation, and fieldbus networks by defining a common communication interface. Compatibility issues between different networks, and ultimately the interchangeability and interoperability of the transmitter to the network. The IEEE1451 family of standards defines the hardware and software interfaces of the transmitter, dividing the sensor into a two-layer module structure. The first layer is used to run the network protocol and application hardware, called the Network Capable Application Processor (NCAP); the second layer is the Smart Transducer Interface Module (STIM), which includes the transmitter and Spreadsheet TEDS. The IEEE1451 working group has proposed five standard proposals (IEEE1451.1-IEEE1451.5), which are aimed at different industrial application field requirements, among which IEEE1451.5 is the wireless sensor communication interface standard.
The IEEE 1451.5 standard proposal was recently introduced in June 2001. An open standard wireless sensor interface was proposed under the existing IEEE1451 cabinet to meet the needs of different applications such as industrial automation. IEEE 1451.5 uses wireless transmission media as much as possible to describe the wireless connection specification between the smart sensor and the network adapter module, instead of the wireless connection between the network adapter module and the network, and realizes the IEEE 802 of the network adapter module and the smart sensor. 11. Interoperability between Bluetooth and zigbee wireless interfaces. The work of the IEEE 1451.5 proposal focuses on the development of communication data models and communication control models in the wireless data communication process. The IEEE 1451.5 proposed standard must have a general extension of the data model to allow multiple wireless communication technologies to be used, mainly including two aspects: First, define a universal quality of service (QOS) mechanism for transmitter communication, which can Any radio technology performs mapping services, and each radio frequency technology has a mapping layer for mapping wireless transmission specific configuration parameters into the quality of service mechanism. The details of the standard are not discussed in detail here.
(3). 6LowPan draft
The wireless sensor network has been associated with the next generation Internet since its inception. The 6LowPan (IPv6 over Low Power Wireless Personal Area Network) is a standard draft that combines these two areas. The goal of the draft is to develop how to transport IPv6 messages over LowPAN (low power personal area network). The current open protocol adopted by LowPAN mainly refers to the IEEE802.15.4 medium access control layer standard mentioned above, and there is no truly open standard support routing function in the upper layer. Since IPv6 is the next-generation Internet standard, it is mature in technology, and the IPv6 protocol can be seamlessly connected to the IPv6 network on LowPan. Therefore, the Internet Engineering Task Force (IETF) has set up a special work. The group formulates related technical standards such as how to send and receive IPv6 packets on the 802.15.4 protocol.
The choice of transmitting IPv6 packets on 802.15.4 is mainly because the existing mature IPv6 technology can well meet some requirements of the LowPan interconnect layer. First, many devices in the LowPan network require stateless auto-configuration technology. In the IPv6 Neighbor Discovery protocol, host-based diversity has provided two automatic configuration technologies: stateful autoconfiguration and stateless autoconfiguration. In addition, there may be a large number of devices in the LowPan network, which requires a large IP address space. This problem is not a problem for the IPv6 protocol with 128-bit IP address. Secondly, if the packet length is limited, the IPv6 address may be selected to include 802. .15.4 Media Access Control Layer Address.
The original design of the IPv6 and 802.15.4 protocols is applied to two completely different networks, which leads to many problems in transmitting IPv6 packets directly on 802.15.4. The packet length of the first two protocols is incompatible. The maximum packet length allowed for IPv6 packets is 1280 bytes. The maximum packet length of the medium access control layer in 802.15.4 is 127 bytes. Because of its own address domain information (even need to leave some bytes for security settings) occupy 25 bytes, leaving the upper load domain up to 102 bytes, obviously can not directly carry packets from the IPv6 network; secondly two The address mechanism adopted by the user is different. IPv6 adopts a hierarchical clustering address, which consists of multiple prefixes of the address segment with a specific meaning and the host number. In 802.15.4, 64-bit or 16-bit flat addresses are directly used. In addition, the protocol design requirements of the two devices are different, and the energy saving problem is not considered in the design of the IPv6 protocol. In 802.15.4, many devices are battery-powered and have limited energy. It is necessary to minimize data traffic and communication distance to extend network life. Finally, the optimization goals of the two network protocols are different, and generally care about how fast in IPv6. The problem of message forwarding is realized, and in 802.15.4, how to achieve reliable communication while saving equipment energy is its core goal.
In short, because the design of the two protocols is different, there are still many technical problems to be solved in IEEE802.15.4 to support the transmission of IPv6 data packets, such as packet fragmentation and reassembly, header compression, address configuration, mapping and management, and network. Routing and forwarding, neighbor discovery, etc., will not be discussed here.
4. Domestic standardization and internationalization
In recent years, the standardization work in the field of domestic wireless sensor networks has made great progress under the promotion of the National Information Technology Standardization Technical Committee (referred to as the Beacon Committee). After more than a year of deliberation, the Beacon Committee organized Chinese and overseas Chinese experts on November 29, 2005, and held the first “Wireless Personal Area Network Technology Standards Seminar†at the China Electronics Standardization Institute to discuss wireless. The development of personal area network standards, market analysis and standards development, the meeting recommended that wireless sensor networks into the wireless personal area network, and set up a special interest group (in addition to low-speed wireless personal area network, ultra-wideband and other interest groups ), since then, China's wireless sensor network standardization work has taken the first step.
After nearly two years of joint efforts by more than 30 domestic research and industrial entities, the working group has organized eight national technical seminars and proposed a 780MHz (779-787 MHz) dedicated frequency band for low-speed wireless personal area networks. Relevant technical standards have been officially approved by the National No Management Committee (using 950MHz in Japan and 915MHz in the United States). For this frequency band, the working group proposed the MPSK modulation and coding technology with independent property rights, and got rid of the patent restrictions of similar foreign technologies. March 3 to 4, 2008, Working Group on Specific Requirements for Telecommunications and Information Exchange between Local Area Networks and Metropolitan Area Networks, Part 15.4: Low-rate Wireless Personal Area Network (WPAN) Physical Layer and Media Access The Control Layer Specification comments were voted and adopted the MPSK and O-QPSK modulation coding technology proposal for the 780 MHz working frequency band as the Co-alternative physical layer specification for low-rate wireless personal area networks (MPSK and O). -QPSK is proposed by relevant groups in China and the United States, and each has intellectual property rights), that is, LR-WPAN can adopt one of MPSK and OQPSK, or use together, and will eventually form the IEEE 802.15.4c standard. In addition, IEEE 802.15.4e, which is mainly drafted by Chinese and Chinese experts and includes the MAC/PHY two-layer protocol, is also in the process of progress (incorporating industrial wireless standard support in IEEE 802.15.4-2006 media access control) ISA SP-100.11a and compatible with IEEE 802.15.4c). This is an important progress in domestic standardization work and an important step in China's participation in the formulation of international standards. The Institute is one of the official members of this working group and has participated in some of these tasks.
Recently, new progress has been made in the standardization of domestic and international wireless sensor networks. First, the National Standards Committee has officially approved the separation of wireless sensor networks from the wireless personal area network working group, and established a wireless sensor network standard working group directly under the National Information Technology Standardization Management Committee (the Secretariat is now affiliated with the Microsystems Institute, One of its member units will work on the development of the standard). The working group is expected to complete the preparatory work around April 10, 2008, which marks a major step forward in the standardization of the sensor network. Second, the ISO has also established the ISO/IEC JTC1/SGSN research group and started. Development of international standards related to sensor networks. China and the United States, South Korea, Japan and other countries participate as important member units. Its first meeting will also be held in Shanghai, China, at the end of June 2008. The meeting not only has experts in related fields at home and abroad to conduct technical discussions on some of the key issues, but also many companies engaged in sensor network applications to bring the latest products to participate in the exhibition. At the same time, Member States will conduct in-depth discussions on the sensor network standard framework to lay the foundation for the detailed design of the draft standard.
Standards are the link between research and industry, and chips are the most direct form of implementation of standards. Participation in standardization work, especially participation in the formulation of international standards, plays an important role in improving the competitiveness and technical level of China's products and occupying the commanding heights of the industry. The ultimate goal of setting standards is to facilitate the improvement of the industry level, the internationalization of products, the protection of independent intellectual property rights, compatibility with similar or supporting products. If we can participate in the development of domestic and international standards related to wireless sensor networks, we will be able to obtain strong guarantees in chip design, solution provision and product manufacturing in this field. As the most direct embodiment of the standard, the system chip will be a key component of the wireless sensor network application system, which is not only the main determinant of cost, but also the main form of intellectual property. The lack of industry standards seems pale and powerless, just a piece of paper; the lack of standardization of chips seems to be nominal, just on paper. However, at present, the level of chip design and industrialization (especially RF chips) is low and the capability is relatively weak. This is two key links in the field of wireless sensor networks. Standard development and communication chips are two indispensable aspects of the current sensor network field.
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