Application and standardization status of IPv6 technology in ubiquitous network perception extension layer

1. Basic concepts of ubiquitous network

Ubiquitous comes from Latin, meaning to exist anywhere. In 1991, Mark Weiser, a computer scientist at Xerox Laboratory, first proposed the concept of "ubiquitous computing", describing that anyone can connect to the network through appropriate terminal devices at any time and anywhere to obtain personalized information services. With the development of IT technology and communication technology, communication networks will not only meet the communication needs between people, but also further develop to communication between people and machines (or objects) and machines and machines, and evolve towards ubiquitous networks. In the future heterogeneous network environment, different levels and multiple network technologies such as wide area networks, local area networks, vehicle area networks, home area networks, and personal area networks will complement each other and develop in an integrated manner. With the support of microelectronics technology, embedded technology, short-distance communication technology, sensor technology, and smart tag technology, they will eventually promote the "realization of a ubiquitous information society."

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Ubiquitous network refers to the use of existing and new network technologies to realize on-demand information acquisition, transmission, storage, cognition, decision-making, and use services between people, people and things, and things and things based on the needs of individuals and society. The ubiquitous network has super environmental perception, content perception, and intelligence, providing ubiquitous and all-encompassing information services and applications for individuals and society.

"5C+5Any" is the key feature of ubiquitous network. 5C refers to Convergence, Contents, Computing, Communication, and Connectivity. 5Any refers to Any time, Anywhere, Any Service, Any Network, and Any Object. The overall meaning is that through the underlying fully connected, reliable, and intelligent network, as well as the integrated IT and communication technologies, communication services are extended to industries such as education, finance, smart buildings, transportation/logistics, health care, disaster management, and security services to provide people with better services.

2. Ubiquitous network architecture

The network architecture of the ubiquitous network can be divided into a three-layer architecture consisting of the perception/extension layer, the network layer, and the application layer.

(1) The perception extension layer of the ubiquitous network uses sensors, two-dimensional barcodes, RFID tags, multimedia information and other information collection terminals to obtain various types of information such as the attributes, identification, status, type, quantity, and intensity of various targets in the physical world, and uses network, information processing and middleware technologies to perform local or global interactive processing and aggregation on the perception information to provide the network layer with perception information of the physical world. The perception extension layer must solve the problems of low power consumption, low cost and miniaturization, and develop towards more sensitive and comprehensive perception capabilities.

(2) The network layer of the ubiquitous network includes the access network sublayer and the core network sublayer. The access network sublayer includes various access technologies such as satellite-to-ground wireless access, wired broadband access, wireless broadband access, and 2G/3G/super 3G mobile access. The core network sublayer includes the existing telecommunications network, the Internet, the radio and television network, the future next-generation network (such as NGN/NGI), and the industry-specific networks built by various industries. Since the ubiquitous network is a network, it requires a unified network architecture and protocol foundation. At present, at the core level, it can be considered to merge with NGN/IMS. The core protocols include SIP and TCP/IP. At the access level, it is necessary to consider the coordination of multiple wired and wireless technologies, such as Wi-Fi, WAPI, 2G, 3G, LTE, UWB, ZigBee, etc.

(3) The application layer of the ubiquitous network mainly realizes information processing, collaboration, sharing, and decision-making, including the application support sublayer and the application service sublayer. The application support sublayer provides unified and fixed network support services to industry services, especially for some industry integration services, so as to support intercommunication between different industries. The application service sublayer includes ubiquitous network public services, industry-specific services, etc. Businesses and applications involve a variety of technologies such as intelligent processing of massive information, distributed computing, middleware, and information discovery.

3. Key technologies of the ubiquitous network perception extension layer

The key technologies of the ubiquitous network perception extension layer include data acquisition technology, wireless/wired transmission technology, networking technology, information processing technology and middleware technology. It also involves the intercommunication technology between the perception extension layer and the network layer.

(1) Data collection technology. It is mainly used to collect physical events and data that occur in the physical world, including various physical quantities, identification, audio, and video data. It can use sensors, RFID, and one-dimensional/two-dimensional codes to obtain object information anytime and anywhere, collect audio and video information through multimedia technology, and obtain object location information through positioning technology.

(2) Wireless/wired transmission technology. It is mainly used to supplement and extend the access network, so that the network can connect various "things" to the network. At present, various short-range wireless communication technologies are mainly used, including IEEE802.15.4, UWB, NFC, Bluetooth technology, etc.

(3) Networking technology. Through wireless self-organizing network technology, scattered nodes are automatically organized into a network within a certain range, so that the information collected by each node can be uniformly processed and transmitted, or through mutual "contact" between nodes, the nodes can negotiate and transmit their respective partial information, ultimately achieving reliable and efficient information transmission.

(4) Information processing technology: Achieve collaborative processing of massive amounts of information and provide intelligent, accurate and diversified information services.

(5) Middleware technology: Shield the differences between underlying software (operating system) and hardware, build a unified development platform, encapsulate common functional components, and provide services for upper-level applications.

(6) Intercommunication technology with the network layer. The perception extension layer can adopt two different technical routes, one is non-IP technology, such as the ZigBee protocol, and the other is IP technology. At present, the network layer mainly uses IP technology to form a network. Therefore, in order to realize the interconnection between the perception extension layer using non-IP technology and the network layer, protocol intercommunication must be achieved through gateway devices.

4. Application of IPv6 technology in the ubiquitous network perception extension layer

4.1 Ubiquitous Network Perception Extension Layer IP Technology Route

From the current technological development, the networking technology of the intelligent terminal in the ubiquitous network perception extension layer can adopt two different technical routes. One is non-IP technology, such as the ZigBee protocol developed by the ZigBee Industry Alliance; the other is the extension of IP technology downward to the perception extension layer advocated by IETF and IPSO Industry Alliance. Obviously, the adoption of IP technology will help to achieve end-to-end service deployment and management, and can achieve seamless connection with the network layer IP bearer without protocol conversion, simplifying the network structure. The IP protocol also has the following characteristics to meet the needs of the ubiquitous network, including:

(1) The IP protocol is an open protocol standardized by the IETF and does not require additional licensing fees to use it.

(2) IP protocol is a lightweight protocol. IP was once considered heavyweight, but recently many small lightweight IP protocol stacks have been successfully developed, such as uIP, Arv6, NSv6, uIPv6, IwIP, etc., which can meet the special needs of low-power, low-storage capacity, and low-computing-power smart terminals in the perception extension layer.

(3) The IP protocol is highly scalable. For example, the IPv6 protocol can support a huge address space and adopt a hierarchical address structure to support a larger network scale.

(4) IP protocol is highly manageable. IP networks have a set of fully mature and widely recognized management protocols and mechanisms.

(5) The robustness, flexibility, and layered architecture of IP protocol design enable it to support almost all types of applications, including low-data-rate applications such as remote device control, delay-sensitive applications such as IP telephony, and large-scale data transfer applications such as file downloads.

(6) The IP protocol is independent of the underlying data link layer protocol. IP technology uses a layered architecture that enables it to work on any physical layer, from wired to Wi-Fi to low-power radio.

(7) IP networks are ubiquitous, and almost all networks provide wired or wireless IP access.

Therefore, from a technical perspective, adopting the IP technology route in the ubiquitous network perception extension layer will be able to better meet the future development needs of the ubiquitous network.

4.2 Application of IPv6 Technology in Ubiquitous Network Perception Extension Layer

In a ubiquitous network environment, to achieve "one object, one address, and everything online", a large number of IP address resources will be required. The current available IPv4 address resources are far from meeting the networking needs of perception smart terminals. Especially after the scale popularization of applications such as smart home appliances, video surveillance, and automotive communications, the demand for addresses will expand rapidly. From the perspective of currently available technologies, only IPv6 can provide sufficient address resources to meet end-to-end communication and management needs. In addition to the general characteristics of the IP protocol described in Section 4.1, the IPv6 protocol also has the following characteristics:

(1) Plug and Play. IPv6 introduces automatic configuration and reconfiguration technology, which can automatically add, delete and update configurations of information such as IP addresses, thus improving the manageability of IPv6.

(2) Security. IPv6 integrates IPSec for authentication and encryption at the network layer, providing end-to-end security for users.

(3) Quality of Service: A new flow tag field is added to enable the source and sink to quickly process real-time services.

(4) Mobility. Mobile IPv6 enhances the mobility of terminals and provides users with permanent online services.

The above characteristics enable IPv6 to better meet the interconnection needs of ubiquitous network intelligent terminals in addition to meeting the needs of huge address space in ubiquitous networks. However, it is necessary to simplify the protocol stack and improve the routing mechanism to meet the special networking needs of intelligent nodes with low power consumption, low storage capacity, and low computing power as well as lossy network environments.

5. Current status of IPv6 technology standardization applied to ubiquitous network perception/extension layer

At present, IETF mainly consists of 6lowPAN, ROLL working group and 6lowAPP responsible for studying IPv6 applications and low-power routing related protocols at the perception extension layer.

(1) The 6lowPAN (IPv6 over Low Power WPAN) working group focuses on technologies such as adaptation layer, routing, packet header compression, fragmentation, IPv6, network access and network management. The working group has completed two RFCs: "Overview, Assumptions, Problem Statement and Objectives" (RFC4919); "IPv6 Message Transmission Based on IEEE802.15.4" (RFC4944).

(2) The ROLL (Routing Over Low Power and Lossy Networks) working group mainly studies the routing issues of low power loss networks. The working group has completed two RFCs: "Routing Requirements in Urban Low Power Loss Network Environments" (RFC5548); "Industrial Routing Requirements in Low Power Loss Network Environments" (RFC5673).

(3) 6lowAPP mainly studies node and network applications based on resource constraints, such as wireless embedded network applications. At present, 6lowAPP is not a working group of IETF. In the IETF75 "BarBOF" meeting, five research areas were identified, including application protocols, service discovery, transmission, security and data representation.

The IPSO industry alliance, founded in September 2008, also strongly advocates the integration of the ubiquitous network perception extension layer into the IP technology system. The goal of the IPSO alliance is to provide users with more information about smart objects, industrial fields and markets. The alliance will provide case studies and white papers, track the standards of IETF and other standard organizations, organize demonstrations and interoperability tests, etc. The first goal of IPSO's work is to achieve interoperability of IPv6 on the IEEE 802.15.4 standard. At present, 4 related white papers have been released, including the application of IP technology to smart objects, lightweight operating systems, 6LoWPAN network standards and neighbor discovery mechanisms.

6. Conclusion

In the ubiquitous network environment of the future, the network will no longer passively meet the needs of users, but will actively perceive changes in user scenarios, interact with information, and provide personalized services to users. According to the current development of technology and business, in the next few years, the ubiquitous network will be in the ubiquitous Internet of Things stage, that is, the main goal is to meet the communication needs of things. Therefore, combined with the large demand for addresses of terminal devices, with the simplification of network structure and end-to-end business management as the starting point, we can consider applying IPv6 technology in the relatively closed Internet of Things to achieve ubiquitous interconnection of smart objects, while driving the maturity of the entire IPv6 industry and laying the foundation for large-scale deployment of IPv6 technology for the next generation of Internet.