Help you understand what is wireless multi-connection (1)

Do you know about wireless multi-connection? It is a technology based on wireless communication technology and maintenance links. It can improve the communication environment of wireless networks and improve the communication quality. So, this article will introduce this technology in detail, from four perspectives, I hope to help you.

1. Overview

With the development of mobile communication technology, a variety of wireless communication systems and technical systems coexist. The second generation of mobile communication system GSM/GPRS, will deploy the application of the third generation mobile communication system TD-SCDMA/WCDMA, Local Wireless Access System, wireless LAN and so on. It is common for mobile communication operators to have multiple wireless communication systems and corresponding wireless communication frequencies.

In addition to how to use the new wireless transmission technology to further improve the spectrum efficiency of the wireless communication system, it is also important to consider how to make better use of existing wireless frequency resources and make full and reasonable use of various wireless systems.

Wireless multi-connection is a new concept in this context. Generally, a wireless communication device can maintain multiple wireless links at the same time. The use of wireless multi-connection can improve the system performance. Through the joint wireless resource management between multiple wireless links, load sharing between different access systems can be realized, in this way, the overall wireless frequency utilization is improved, the business data rate is improved, the user experience is improved, and the "always on" function is better supported in the Next Generation Network. In addition, multiple wireless connections can improve the switching performance of mobile communication systems, reduce switching latency, and improve system reliability.

In this article, we will focus on the concept and basic meaning of wireless multi-connection, analyze the implementation technology of wireless multi-connection, and discuss the required international standardization work.

2. concept analysis and implementation technology of wireless multi-connection

Wireless multi-connection is a wireless communication device capable of initiating and maintaining multiple wireless connections. There are four wireless multi-connection modes. This section describes the four wireless multi-connection modes and their implementation technologies.

2.1. Mode 1: Virtual Multi-connection with the same access technology

Virtual Multi-link with the same access technology means to maintain only one wireless link at a time while maintaining the wireless link, measure air interfaces of other same access technology systems that are not on the same frequency point and complete necessary Signaling connection preparation. If there is a problem with the current wireless link or the system load is too high, you can quickly switch to another wireless link that is ready for signaling.

In this scenario, multi-connection is the most basic form in the concept of multi-connection. In essence, it is still a single connection, only systems that can connect to the same technical system in multiple frequencies within a period of time from the system perspective have the basic features of wireless multi-connection. The advantage of Multi-connection in this mode is that it can improve the switching performance of the system and improve the reliability of the system. When the current system load is too heavy or the wireless link quality is seriously reduced, you can quickly switch to the ready Second Wireless Link.

Some mobile communication systems, such as GSM, already have the ability to measure different frequencies. However, in order to save system overhead and air interface resources, no Signaling connection is established in advance. Therefore, in this scenario, the focus of the research is on how to strike the optimal balance between system overhead and switching performance.

2.2. Mode 2: Same access technology with different frequency and multiple connections

This multi-Connection Mode means that mobile communication devices can maintain wireless connection with two systems with the same technical system at the same time in different frequency bands. A mobile communication device can use a separate MAC function entity or multiple MAC function entities to complete multiple physical layer connections.

In this multi-connection mode, Two RF receiving devices are required for the mobile communication terminal to simultaneously process physical layer connections in different frequencies. It also requires the same or different MAC processing entities, especially in OFDM systems. Multi-Band OFDM is also a new concept and technology that will be introduced into the MPI-Advanced system.

The advantage of this multi-connection mode is that the non-continuous spectrum can be used more freely. The frequency of the MMS-Advanced System is likely not to be available in mass pairs. The multi-band method can be used to treat discontinuous frequencies as fragments of physical resources, constitute a more powerful physical layer.

In this scenario, there are two problems that need to be focused on. First, we need to solve the problem that the physical layer can simultaneously process signals in two frequency bands. This can be done through RF or baseband digital signal processing methods. Secondly, MAC management and control problems are required. If you only use RF signals of different frequencies as part of the physical layer, you only need one MAC layer and its functional entities to process connections of multiple frequencies. If the physical layer is considered as an independent part, the processing method is closer to the Cross-Frequency Dual-receiver, and multiple MAC functional entities are required. When multiple MAC functional entities are required to complete the wireless multi-connection function, coordination and management between multiple MAC functional entities becomes the most urgent problem to be solved.

2.3. Mode 3: Virtual Multi-connection with different access technologies

For Virtual Multi-connection of different access technologies, mobile communication systems only need to maintain one wireless link at a certain time point, but need to measure other systems using different access technologies, and establish necessary signaling connections in advance under certain conditions. This wireless multi-connection method requires mobile communication devices to have multiple MAC and corresponding physical layers required by wireless technology, but does not require different physical layers to work at the same time, instead, multiple connections are used in time division multiplexing.

In fact, the current wireless communication system, especially the communication technical standards set by the same Standardization Organization, is out of the need for backward compatibility and smooth network evolution, the measurement of the existing system is considered in the system and protocol design. Therefore, this multi-connection scenario is within the scope of the International Standardization Organization. For example, GSM and WCDMA systems and various interoperability methods between LTE and WCDMA are typical Virtual Multi-connection between different access technologies and access systems.

However, standards formulated and maintained by international standardization organizations often do not take into account the measurement of different systems, and do not make necessary signaling preparation. Generally, data is forwarded at the core network layer, that is, the two systems are "loosely coupled. Therefore, the Virtual Multi-link proposed here for different access technologies requires that the two systems have a "tightly coupled" relationship and require necessary air port Measurement with signaling coordination and preparation.

The advantage of this multi-connection mode is that multiple wireless frequency resources can be used together to make full use of the capabilities of different wireless access systems, which can improve the reliability of the mobile communication network. Through the joint resource management of the two systems, resources can be used more efficiently. At the same time, for users, this multi-connection mode can improve the user experience, so that users feel that in different environments, the best connection is always maintained, with the support capability of "always on.

Two or more MAC layers and physical layers are required in the terminal device, and dual receivers are available. Due to the interference of RF, the dual-receiver does not work at the same time. In this multi-connection scenario, the focus of the research is to conduct measurements between different systems and determine the strategies for preparing signaling in a timely manner, it improves the system's fast switching performance, improves load balancing among different wireless systems, and reduces system overhead.