1-541-955-6900 success@visp.net

New to Fixed Wireless? A MAC Protocol Primer for Outdoor Environments 

by | Oct 1, 2020

Network communication is critical to keep subscribers happy and your WISP profitable

Communication is important in thousands of scenarios. In the ISP space,  constant network communication ensures devices remain connected and responsive.

This simplistic description doesn’t take into account the complexity of an ISP network. In addition to customer WiFi routers, communication towers,  and the WISP network core, there are numerous access points, backhauls, and routers in between that receive and send signals to keep packets flowing. Network communication includes both transmission and reception.

Seven communication layers make up the network and the MAC Access Control sublayer resides in Layer 2, called the Data Layer. This layer is responsible for keeping the data moving between nodes. The MAC address is a unique identifier for each piece of hardware in the network that makes up a node in the MAC layer.

Outdoor environments complicate communication. A network administrator building a network must plan for disruptions from weather, interference and other factors to keep subscribers connected.

This brief primer on wireless MAC protocols for outdoor environments is designed for individuals who are new to the fixed wireless broadband industry.

Network Communication Annoyances

A helpful way to visualize access control is as if you are creating an environment for a public speaker. Your access point is the speaker, and subscribers are the audience. Little or no echo and low noise means communication can be natural and efficient.

If your access points are victims of bad engineering and riddled with echoes or noise, one or more of your subscribers become the annoying guy in the back row who repeats, “I can’t hear you!” You’re frustrated and the affected audience members feel let down.

A network must take into consideration transmission and reception. It’s configured as either a full-duplex system that sends while it receives or a half-duplex system that performs one of those actions at a time. 

Many fixed wireless solutions are half-duplex systems, which means they do not talk and listen at the same time. This is also true of Wi-Fi.

Full-duplex systems separate wireless channels

. Many fixed wireless half-duplex PtMP systems use a single frequency space to separate reception (Rx) and transmission (Tx). They use timing, similar to how respectful people wait for one another to finish speaking before they speak. 

Outdoor Fixed Wireless 

There are some quirks that you should consider for outdoor fixed wireless, including the hidden node problem. This occurs when a node can communicate with an AP, yet interrupts other nodes due to insufficient schedule technology for fixed wireless.

The Carrier-Sense Multiple Access (CSMA) MAC protocol detects the absence of another signal in a shared transmission channel before sending a message to a node. If there is a transmission in progress, it waits until the transmission is completed before “talking”.

Although it works well for WiFi where clients can hear one another, the use of directional antennas, frequency of obstacles, and distance in outdoor fixed wireless environments will influence the viability of the CSMA protocol. 

Different vendors have different MAC protocols and could have a substantial impact on the scalability of your outdoor fixed wireless deployment. With the wrong configuration, you’ll experience a decline in performance and angrier customers as a result. 

Timing Solutions

To address this issue, manufacturers have stepped in to provide solutions to outdoor fixed wireless modulation and timing issues.

Cambium, Radwin, MikroTik, Mimosa and Ubiquiti are among the leading vendors that have developed solutions for time-slot protocols for the fixed wireless broadband market. They schedule transmissions and receptions and each action waits until it’s their time to talk or listen. 

4G and 5G LTE address mobile broadband issues with components that help a device move between sectors. Pioneers like BaiCells, Telrad, Cambium and Airspan are making great strides in adopting LTE throughout the industry. But some prefer the cost and data delivery of traditional fixed wireless PtMP solutions over LTE. 

PtMP Solutions

As you investigate PtMP solutions, keep in mind that each vendor has their own scheduling algorithms. When you use Time-Division Multiple Access (TDMA) with GPS synchronization, your APs don’t hear each other due to the synchronized listening times and clients are directional so GPS synchronization can greatly improve your network’s efficiency. 

When you have vendors that support frequency reuse, it allows you to use your spectrum efficiently, which is the most priceless resource a WISP has. 

Conclusion

There are answers out there for those who search for them — you just have to know where to look. A big advantage in the internet service providers’ space is the willingness of experienced WISP owners and operators to help those who are just coming up. 

To get answers to your network communication questions, visit these free resources: 

WISP Talk – Private Facebook Group

Everything WISP – Private Facebook Group

WISPA – Wireless Internet Service Providers Association

Visp.net Blog

Start Your Own ISP

If you’d like to hire a consultant, contact Visp.net at – we work with many experienced consultants and are happy to refer them. 

To learn more about protocols for the Node Problem, visit the Wikipedia Hidden Node Problem article. (https://en.wikipedia.org/wiki/Hidden_node_problem)

Find out more about Carrier-sense Multiple Access transmissions and Time-Division Multiple Access at Wikipedia. 

Authentication and Provisioning

The system is redundant, scalable and automates control of subscribers’ access, speeds and usage.

Automated Suspension and Reactivation

Train your subscribers to pay on time and make payments easy to get back online.

Activation Servers Fuel Growth

Speed up on-boarding for point-to-point or point to multi-point connections and Wi-Fi at RV parks, campgrounds or marinas.

“It does what I need and more, the support is top notch.“

~Tristan Livingston (NTX Fiberwave)

“Congratulations on having such fine staffing quality on your front lines.“

~Ned Schuman (Founder, Olympus)

“Amazing how quick you guys get things done!“

~Renaldo Coakley (Coakster Wireless)

“Always works, always getting improved. Thanks VISP Team!“

~Louis Uttaro (Oso Internet)

Related Articles

Is Passive Churn Crushing Your Profitability?

Is Passive Churn Crushing Your Profitability?

Can you retain customers despite this subscription business menace?    There are only three ways a WISP or any business can grow -- activate new subscribers, retain customers and get them to spend more each month. Sure, adding new subscribers builds your customer...

A Sales Incentive Plan to Retain and Motivate ISP Salespeople

A Sales Incentive Plan to Retain and Motivate ISP Salespeople

ISP salespeople are essential to keep a steady stream of new subscribers coming into your organization. But, hiring and keeping good professionals requires more than just a base salary and vacation. Discover how well-structured sales incentive plans can help you to attract the best and brightest.

One Habit Ignites Continuous WISP Success

One Habit Ignites Continuous WISP Success

Your success is up to you — the focus, action and habits that you apply to your goals determine how far you’ll climb. But, is there a magic formula that can transport you further into the stratosphere? Yes. Elite business leaders have a trait in common — they are...

?