Detailed Analysis of the Technical Structure of Mesh Ad Hoc Network
2021.08.21 / By hqt
1. Introduction and main technologies of MESH ad hoc network
MESH ad hoc network is a new type of wireless network that is completely different from traditional wireless networks. It is a technology that dynamically establishes new links and connects with other nodes. It has the advantages of self-organizing network, self-healing, multi-hop cascading, node self-management, etc., which can greatly reduce the cost and complexity of network deployment.
At present, the industry’s MESH ad hoc network mainly uses the following technologies:
1) According to the networking frequency band, Mesh is divided into multi-frequency multi-channel networking and single-frequency networking. Single-frequency networking uses a single frequency for transmission and reception, reducing bandwidth capacity by half. In multi-frequency multi-channel networking, the device uses multiple orthogonal frequencies for different links, which can increase system throughput.
2) In terms of radio frequency technology, in order to improve the transmission rate and performance, OFDM, MIMO, smart antenna and other technologies have been widely used in recent years.
3) In terms of resource scheduling, it is usually divided into CSMA/CA mode and TDMA mode. CSMA/CA adopts the resource competition mode, but when there are many nodes and hops, and the network load is high, the effective resource utilization rate is low. TDMA mode is a scheduling mechanism based on time allocation. When the network load is heavy, the efficiency is high.
4) In terms of network routing algorithms, unlike the RIP and OSPF routing protocols used in fixed routing, common Mesh wireless routing algorithms include DSDV, DSR, and AODV.
2. Wireless products based on MESH ad hoc network
In the early days, broadband MESH products widely used Wi-FiMESH technology based on CSMA/CA. Through the multi-frequency modular design, it can provide high-capacity, low-cost wireless access solutions in the ISM band. Wi-Fi MESH products are widely used in the construction of ‘wireless broadband cities’ in European and American countries, and are also widely used by domestic operators, schools, enterprises, and factories. During this period, a large number of Wi-FiMESH manufacturers such as SkyPilot and Azalea appeared. However, after the commercialization of 3G/4G, the wireless broadband access market has shrunk sharply, and many manufacturers have closed down.
Wi-Fi MESH is not suitable for industries such as emergency communications due to frequency band, bandwidth, stability and other issues. MESH products that use the same frequency TDMA method have become a hot topic in the industry. Such products generally adopt the FPGA+ADC chip architecture, which can flexibly design the underlying wireless communication protocol according to the channel characteristics of the application scenario, and widely use OFDM, MIMO and other technologies. The cost of products using this solution is higher, the power consumption is larger, and the product cycle for developing stable work is longer. At present, there are many companies on the market that adopt this scheme.
In addition, there is a MESH scheme using LTE related technologies, which fully integrates the LTE physical layer technology, and the frame structure is specially designed. Different modulation and coding methods can be applied to adapt to different channel changes to obtain maximum transmission efficiency. LTE is a very mature and mature technology, and its reliability and stability can be guaranteed. However, this kind of scheme has a high development threshold and a large investment, and there are few companies that can do low-level R&D.
3. Future development trend of MESH ad hoc network
Equipment miniaturization and portability are one of the future development trends of MESH products. On the premise of fully considering the application scenarios and guaranteeing the necessary functional performance, the portable and smart technology is studied to meet the requirements of single-person carrying and unmanned aerial vehicles.
In the field of emergency communications, Mesh self-organizing network technology is also widely used. The integration of Mesh with other private network communications, satellite communications and other systems is also the focus of future development.