Challenges of Deploying Wireless Mesh Networks

Wireless mesh networks have been around since the early days of Wi-Fi and have recently gained more and more attention in the consumer market. However, there are also wireless mesh solutions for the enterprise market, and advances in wireless technology have increased the feasibility of deploying enterprise mesh networks, especially in environments where running cabling is impractical.

The idea behind wireless mesh networks is that not all access points (APs) have to be plugged into the wired infrastructure. Those that are not plugged in connect wirelessly from a nearby mesh AP. Small mesh networks may only require a single mesh AP plugged into the wired network, larger networks will require multiple mesh APs to be plugged into the network to support wirelessly connected networks.

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Wireless Mesh is different from WDS

Wireless mesh technology is different from the wireless distribution system (WDS) feature supported by most routers and APs. Although both can extend a Wi-Fi network to APs without running Ethernet, there are some key differences between them. Mesh is basically a smarter version of WDS that is easier to configure and deploy.

WDS typically only allows you to configure APs to wirelessly connect to another AP that has a wired network connection. Wireless connections to host APs are typically static and require manual configuration of MAC addresses. Additionally, the number of wireless links between APs is limited, and security/encryption of wireless APs can be complex. Additionally, WDS links typically use the same radio and channel as regular Wi-Fi traffic, which can impact Wi-Fi performance.

Mesh APs can connect wirelessly to mesh APs that have a wired or wireless connection to the network. Many mesh APs have dedicated radios for wireless links between mesh APs, which allows ordinary dual-band radios to serve Wi-Fi users.

The wireless links between APs are designed to be automated and provide self-healing multi-path links or hops. This helps simplify setup and provide better redundancy. So if one mesh AP fails, or the environment changes and negatively impacts the wireless link, the wirelessly connected mesh APs are designed to either reach another mesh AP or find a better path to reach the host AP.

Deploying mesh APs makes more sense than traditional APs

In some cases, it makes sense to consider deploying mesh APs (rather than traditional APs) in your enterprise. For example, in an environment without any existing cabling, mesh network installation can be faster and cheaper. Mesh networks are particularly important when running cables is difficult or impossible. This situation may occur in old historic buildings, parks, and outdoor venues, etc.

Mesh networking is ideal for temporary indoor or outdoor networks, such as events and conferences in public places. It is also suitable for rented spaces, such as offices, where there are no feasible cables.

Even if pulling cables isn't a big issue, you might still consider using a network that may see drastic construction or environmental changes in the future. The same applies if the area or level of coverage required changes significantly. A mesh network allows you to more easily patch capacity holes or modify coverage.

Deployment Challenges of Wireless Mesh Networks

Throughput is one of the most important factors to consider before using a mesh network. For situations that require higher throughput and faster Wi-Fi speeds, traditional APs may be a better fit. In a wireless mesh configuration, you have to deal with a huge bandwidth loss from one repeater to the next; for each wireless link between mesh APs, throughput drops by about 50% from the previous AP.

In some cases, the throughput issues with mesh APs are acceptable, especially given the data rates offered by 802.11ac. If users will be doing regular web work or web browsing, the throughput drop may not be an issue. However, if many users need to use high-bandwidth applications such as HD video streaming or photo uploading, it will certainly be noticeable.

Using a mesh network also introduces more variables when it comes to Wi-Fi surveys and design. Enterprises need to be vigilant about mesh AP placement and consider the number, length, and signal quality of wireless links between mesh APs. Generally, you don't want to return more than three times to a host AP that has a wired connection to the network. You also have to consider the power source of the AP when designing, which may limit your placement.

Keep in mind that in most cases you'll need more mesh APs to cover a given area than you would with traditional APs. Mesh APs need to be placed closer together so that they can communicate with each other effectively. Any money you save by not running cables is offset by having to purchase a greater number of mesh APs.

Compatibility is also an issue. Despite the long-standing 802.11s standard from the IEEE and the Wi-Fi EasyMesh standard from the Wi-Fi Alliance, most mesh APs aren't compatible across vendors. So, stick with one brand, and perhaps the same model, just to be safe. Consider keeping a few extra mesh APs for replacement or network expansion, just in case you can't buy that model in the future.

Many enterprise-class APs have mesh capabilities built in, even though most IT staff typically only use traditional AP deployment modes. However, APs that are marketed as mesh APs typically have more advanced mesh features. The specific features, limitations, and performance vary widely between AP vendors.