Wireless Mesh Networks (Wi-Fi Mesh)

Wireless mesh networks (WMN) are wireless network structures in which nodes (network routers and clients) self-organize and dynamically establish connections without requiring a central infrastructure. In these networks, nodes achieve end-to-end data transmission by forming multi-hop connections directly or indirectly with each other. Mesh networks hold a significant place among wireless communication technologies due to their flexibility, scalability, and self-healing capabilities.

Definition and Structure

The fundamental components of wireless mesh networks are mesh routers and mesh clients. Mesh routers include multiple wireless interfaces in addition to the functions of traditional wireless routers, supporting the network infrastructure. These routers provide extended coverage with lower transmission power through a multi-hop communication system. Mesh clients are typically user devices that can dynamically connect to the network.

(Source: Generated by artificial intelligence.)

Mesh networks offer high flexibility through automatic node interconnection and self-configuration. These networks are generally classified into three architectural types:

Infrastructure (Backbone) Mesh Networks: Connect wired networks to wireless devices. Mesh routers function as central control units linking the wireless network to the wired network.

Client Mesh Networks: An independent local network formed by client devices using ad-hoc or peer-to-peer connections without reliance on a wired infrastructure. Each node serves both as a client and a router.

Hybrid Mesh Networks: Combine ad-hoc and infrastructure topologies. Mesh routers form the backbone of the network, while clients can also perform functions such as data packet routing.

Characteristics

Wireless mesh networks are distinguished by the following features:

• Low Cost: Provide an economical solution due to the widespread use and mature technology of the Wi-Fi standard.
• Decentralized Structure: Enable connectivity without a central infrastructure, offering advantages especially in rural or isolated areas.
• Energy Efficiency: Nodes consume low power and can operate using natural energy sources such as solar power.
• Flexibility and Scalability: A node can automatically join the network upon detecting a neighboring node, allowing the network to be easily expanded.
• Redundancy and Reliability: Nodes maintain network continuity and reliability by communicating through multiple paths.
• Easy Setup and Maintenance: Nodes preloaded with mesh software can be quickly deployed, and the network is dynamically configured.
• Security: Provide security services such as data confidentiality, user authentication, access control, and service continuity.

Routing and Channel Assignment

Routing is essential for the efficient operation of wireless mesh networks. Various metrics used during routing ensure that data packets reach their destination via the optimal path. Metrics such as Hop Count, Expected Transmission Count (ETX), Expected Transmission Time (ETT), and Weighted Cumulative ETT (WCETT) have been developed to improve data transmission quality.

Routing protocols vary according to the characteristics of the network:

Ad-hoc Based Protocols: Protocols such as AODV, DSR, and OLSR are suitable for networks with mobile nodes.

Controlled Flooding Protocols: Ensure controlled data dissemination among nodes.

Traffic-Aware Protocols: Optimize routing by monitoring network traffic.

Opportunistic Routing Protocols: Dynamically select the most suitable path based on the current status of available routes.

Multi-Channel Multi-Radio Architectures

To enhance the performance of mesh networks, multi-channel multi-radio (MCMR) architectures have been integrated. These architectures aim to reduce interference and increase network capacity. In MCMR networks, channel assignment is a critical process, employing fixed, dynamic, and hybrid assignment schemes. Architectures incorporating directional antennas have been developed to reduce interference and improve routing accuracy.

Application Areas

Wireless mesh networks can be used in various scenarios:

Community Mesh Networks: Provide services such as shared internet access, security cameras, emergency communication, and local market platforms within neighborhoods.

Municipal Mesh Networks: Used in urban commercial areas, tourist information points, and citizen service applications.

Home Mesh Networks: Enable connectivity for audio, video, telephony, and smart devices within households.

Campus Mesh Networks: Offer seamless internet access across classrooms, laboratories, and administrative areas in universities and educational institutions.

Rural Area Mesh Networks: Provide low-cost and sustainable internet access in isolated regions.

Spontaneous Mesh Networks: Create temporary networks for data, voice, and video services.

Application Example 1

In university campuses, mesh networks are used to provide wide coverage and reliable connectivity. For instance, in one study, a mesh network was designed to replace the existing star-topology Wi-Fi network. The wireless internet service provided by 18 access points was insufficient because each access point could support only 20 users. The proposed mesh network was designed by placing eight routers at specific locations. Simulation results showed that the mesh network achieved higher performance (24,000 bit/s compared to 15,000 bit/s), lower latency (0.0007 ms compared to 0.0084 ms), and greater packet delivery than the existing network.

Application Example 2

Mesh network technology is also used in applications requiring high bandwidth and low latency, such as video surveillance systems. For example, a large-scale video surveillance system deployed on a university campus was built using a mesh network infrastructure, and the impact of routing algorithms on video quality was analyzed. In this system, multi-path routing was employed to achieve load balancing, fault tolerance, and high total bandwidth.

Application Example 3

In rural areas, mesh networks are ideal for providing low-cost and sustainable internet access. A mesh network project implemented in a rural community was developed with community participation and applied with respect for local traditions. The network was established using nodes powered by solar energy and open-source software. The project aimed to ensure sustainability through training local technicians and implementing modular electrical systems. However, social and cultural dynamics emerged as key factors influencing the project’s success.