Troubleshooting is usually necessary for commissioning a new project, expanding an existing system, and of course to repair a malfunctioning system. Whether it is mechanical, wired or wireless, troubleshooting has as much to do with technique as it does the particular devices involved.
The term wireless has been redefined over time. Wireless can mean there are no physical connections required for the device to operate. It may mean the device does not require a wired connection or a power supply to communicate with other devices. It may mean that the device requires wired power to operate but no physical connection to communicate with other devices.
Since the introduction of wireless, the major obstacle to its acceptance has been reliability. Reliability is reduced when a device (transmitter or receiver) does not apparently function, or when there is a degradation of communications between devices due to factors affecting the range of the devices. Degradation of communications is manifested by a loss or weakening of the signal, or a decrease in bandwidth or the amount or quality of data.
Reliability can also be taken to refer to not only the safe communications between wireless points, but also the security of the information contained in the communications.
The security of data has become a major concern in our society. Network security, data encryption and other protective tactics are specialties in their own rights. The Locksmith Ledger will explore wireless and network security in future articles.
With all the wireless equipment in our world, no doubt Locksmith Ledger readers are thinking of their own personal experiences with theses issues; such as losing the picture on their TVs and dropping calls on their cell phones.
In the professional environment where wireless technology is part of our security and safety systems, aberrations in wireless performance must be ideally eliminated or at least minimized, since lives may be at stake.
Properly designed professional wireless systems incorporate some degree of fault tolerance into their design.
Fault tolerance is the property that enables a system to continue operating properly in the event of the failure of some of its components. If its operating quality decreases at all, the decrease is proportional to the severity of the failure. With a system that is not fault-tolerant, a small failure may result in the device malfunctioning.
A fault-tolerant design enables a system to continue its intended operation, possibly at a reduced level, rather than failing completely.
Wireless hardware requires power to operate, and often wireless equipment uses batteries for power. In other applications, power is provided by a more permanent source such as a wall receptacle, and an internal battery in the hardware is used to backup the system to keep it operating through temporary interruptions of power.
With mobile type equipment which is by definition always moving, operating range is a major variable which has to be overcome.
Those Locksmith Ledger readers who have experience with wireless probably have observed where wireless signal strength can sometime be affected in unexpected ways. Signal propagation is not intuitive. I have found that the issues associated with the wireless topologies used for security and access control are analogous to those experienced with Wi-Fi and 3G-4G. The penny in the socket technique is as helpful as it ever was.
Interference or signal degradation can be caused by many environmental factors such as microwaves leaking from equipment example: a microwave oven), industrial equipment, metal appliances or metallic coating or an impeded line of sight. The sensitivity of a wireless signal has to do with its frequency band.
For wireless applications where equipment may sit dormant for extended periods and only be called upon to work in an emergency, there is a concern that the idle equipment will not work. This problem was largely resolved with supervised wireless. The receiver and the transmitter conduct regular self-tests, assuring the equipment has adequate power and the transmission path has not been blocked.
Numerous methods employed in wireless designed to overcome range issues.
A Wi-Fi repeater (also called wireless range extender) takes an existing signal from a wireless router or wireless access point and rebroadcasts it to create a second network.
Since only one wireless device can transmit at once, wireless transmissions are doubled (router to repeater and then repeater to client versus just router to client). Wireless throughput is reduced by at least 50 percent. Wireless interference (e.g., with other networks on the same channel) is at least doubled.
A star network is a situation where each of the endpoints (clients or nodes) communicate directly back to a central hub, or host.
A mesh network is a network topology in which each node relays data for the network. All mesh nodes cooperate in the distribution of data in the network.
Mesh networks can relay messages using either a flooding technique or a routing technique. With routing, the message is propagated along a path by hopping from node to node until it reaches its destination. To ensure all its paths' availability, the network must allow for continuous connections and must reconfigure itself around broken paths, using self-healing algorithms such as Shortest Path Bridging. Self-healing allows a routing-based network to operate when a node breaks down or when a connection becomes unreliable.
As a result, the mesh network is typically quite reliable, as there is often more than one path between a source and a destination in the network.
A mesh network whose nodes are all connected to each other is a fully connected network. Fully connected wired networks have the advantages of security and reliability.
Troubleshooting Tips
Troubleshooting wireless networks’ performance can seem like a baffling challenge but just consider that there are really just two main factors to consider—coverage and speed.
The Locksmith Ledger asked some industry insiders for their advice and procedures for troubleshooting wireless systems. Following are a few key questions and some expert advice.
How do you instruct your customers on assessing wireless signal strength, and what methods or solutions do you offer to extend wireless signal strength?
Adam Auer, Sr. Product Manager for Securitron: Our customers receive training which covers radio ranges and suggested placement. Configuration tools also include a simple signal strength indicator. Wireless performance can be improved with an optional antenna accessory.
Fred Dawber, CANSEC: No Green LEDs - no connection. 1 to 3 Green LEDS and you are good to go. It needs to be just that simple. No meters, no configuration software, no RF sniffers. When we are asked by a customer if our AIR-485 modem will work in a given situation, we always give them the same answer. We don’t know. Every site is different ‑ Different ranges, different background RF, different buildings. There is no way to know for sure without taking a couple of devices to the site, placing them where they need to go, putting them in Range Test Mode and checking the LEDS.
If they do not work on your site, simply send them back for a full refund. We even have a battery pack that you can use to do a walk test with the Slave unit so you can see where it works best. You can see a live AIR-485 rang test on our web site at http://cansec.com/support/online-training-videos/videos/video/latest/air-485-walk-test.html or on Youtube at https://www.youtube.com/watch?v=6Q6FNcGA4m8.
Vince Ricco, Business Development Manager, AXIS: First, we would never recommend or instruct and end-user on testing wireless signal strength unless they had a wireless expert on staff. That being said, there are many tools today that make signal testing much more simple than in the past. Companies like Fluke have test equipment and associated applications that can give the tester a very clear picture of transmit and receive signal strength as well as detect potential interference signals coming from other wireless systems nearby.
There are also more options today to deploying wireless end-points to avoid weak signals as well as signal interference. Some examples are Cambium Networks who make a variety of licensed and unlicensed wireless solutions for “Point to Point” as well as “Point to Multi-Point” connections. Cambium, as well as other similar technologies such as RadWin, Fluidmesh and Firetide, are also in this Enterprise Class outdoor solution environment. Aruba is doing a great job with more traditional mesh wireless connectivity for indoor / outdoor use and scale from simple low count connections to Enterprise Deployments. There are also a handful of traditional wifi solutions out there such as Ruckus and Xirrus.
The reason I bring all of this up is you can pretty much break down the connection requirement and weigh this / these out with the type of wireless system you will require. If the connection is mission critical, the integrator or end-user is most likely going to want to look at a system that is more signal strength robust and less interference susceptible. It is always a matter of weighing out cost versus need or benefit. There is always that balance between technology capabilities and budgets.
A couple of interesting alternative technologies out there today are companies like SIKLU and Sierra Wireless. When I look at SIKLU’s wireless technology, I think of a simplified Media Converter approach where the media happens to be wireless. They are worth a look for campus and small municipal requirements. Sierra Wireless as well as CradlePoint are both doing great work enabling cellular Service Provider connections via LTE or 4G carrier networks.
There are a few other very localized technologies such as Z-Wave and Zigby that could be looked at but this is not an area of expertise for me.
As an Network Connected Camera, Access Control and Two Way Audio manufacturer, we really look to our technology partners to be the experts and advisors as well as our integration channel. My strongest recommendation to your audience is to clearly understand their requirement first.
- Is this primarily indoor, outdoor or a mix of both?
- If I lose signal or connectivity how bad will the result be (inconvenient, costly or life threatening?)
- Understand my environment in terms of how much wireless signal is in my environment, either owned or in nearby business or entities.
- Do some basic research on the available technologies for my application(s) (video, access control, motion detection, etc.)
Note: Video is going to take more bandwidth and some wireless manufacturers handle this better than others in terms of Application Priority or Quality of Service.
Lastly, rely on the experts to advise you whether in house or your integration partner. Every wireless manufacturer that I work with as a Technology Partner has exceptional support and tools to help select the right technology for specific applications. Don’t discount your access directly or indirectly to these companies.
Chris Wilson, Product Manager for Paxton Access: Paxton offers a signal strength indicator within our Net2 software to allow both installers and end users the ability to see the signal strength of the various wireless devices on the system. Paxton offers the Net2 AirBridge for secure wireless communication to the locksets without fear of interference with building WiFi or the ability for someone to 'see' them from a traditional wireless connection.
For more information, visit http://www.paxton-access.com/products.asp?id=011,24&strStage=product_page&strFamily=net2&strGroup=group-05138
