No Strings Attached

Benefits outweigh risks in choosing wireless access control solutions

• By Ray Shilling
• Jun 30, 2008

Much attention has been given to the development and deployment of IP-based video surveillance systems. However, the adoption rate of these new technologies has been slowed, in part, by the heavy bandwidth consumption of video streams and their adverse impact on the network.

Meanwhile, unhindered by these restraints, manufacturers of relatively low data-rate access control systems gradually have been introducing network-based offerings of their own. The idea is to take advantage of the powerful and ubiquitous TCP/IP communication platform without the drawback of convincing the IT department to permit consumption of large quantities of their most precious commodity: bandwidth.

Furthermore, the IP network is reasonable to deploy and universally understood. IT professionals from any nation work within the same framework and rule set, therefore installation and configuration challenges associated with proprietary technologies are all but eliminated.

However, in many cases, a wire-line network connection is not readily available at all locations where access control points may be required. Few buildings—even those that are relatively new—include network connections (RJ-45 ports) at their doors and gates. As a result, wireless technologies are being considered to deploy these Ethernet-based edge devices. End users should explore many factors when designing and deploying a wireless Ethernet-based access control system.

Traditional Protocols
With its introduction several decades ago, electronic access control has solved many of the limitations of mechanical locks and keys. A wide range of credentials can be used to replace mechanical keys; the electronic access control system grants access based on the credential presented.

When access is granted, the door is unlocked for a predetermined time, and the transaction is recorded. When access is refused, the door remains locked, and the attempted access is recorded. The system also will monitor the door and alarm if the door is forced open or held open too long after being unlocked.

In most access control solutions, the system uses a simple challenge-response system to allow access to a door or gate. When a credential is presented to a reader, it sends the credential’s information, in the form of an encrypted bit string, to a control panel. The control panel compares the credential’s number to an access control list, grants or denies the request and sends a transaction log to a database. When access is denied based on the list, the door remains locked. If there is a match between the credential and the access control list, the control panel operates a relay that, in turn, unlocks the door.

Therefore, communication typically is taking place between the access control hardware at the door and a panel containing the system intelligence and database of authorized personnel. This communication traditionally has taken place along standard low-voltage cabling, creating a dedicated loop between the two devices. The advantage of this dedicated design is that it allows the system designer complete end-to-end control of the system’s cabling, without concern for impact from other devices running on the same wire. The principal disadvantage is that the reader devices must be hard-wired to the central panel to facilitate communication, and therefore costly cable runs to every access-enabled door are required. The system cannot be easily accessed from other geographical locations.

Why Use Ethernet?
Before examining the case for wireless technology, first understand that an Ethernet-based IP solution is preferred over a traditional closed-loop proprietary protocol. Here are the most compelling reasons:

Ubiquitous existing infrastructure. Billions of linear feet of Cat-3, Cat-5(e) and Cat-6 copper cabling and optical glass fiber are already installed worldwide. TCP/IP networks are everywhere and are being used to support data transmission in almost every vertical market.

Ethernet (IP) technologies also are widely understood by many IT and business process professionals; therefore, it is easier to conduct discussions among disparate groups within a company to reach consensus and share network resources among users.

Finally, since TCP/IP networks are standards-based, manufacturers can develop and bring to market products that are cost-effective and readily upgraded.

Thus, with this infrastructure in place, access control companies are providing customers with the ability to leverage the existing network and not requiring them to run new dedicated low-voltage cabling from every door controller and/or card reader to a centralized database server.

Cost. Since so much of the TCP/IP network infrastructure already exists— and in many cases is underused and contains extra capacity—the system designer ought to consider using existing network cabling prior to specifying a solution that requires new low-voltage cabling installation. Fortunately, data rates required for access control are low, therefore the system designer can obtain permission from the IT department to allow the system to use the current TCP/IP network.

Scalability. Access control systems are by their very nature spread out across large areas. This is usually because the points of access or egress are at the edge or perimeter of a building or facility. It makes perfect sense that the ideal technology to communicate between these devices is one tuned to fit large areas.

As a result, when discussing which platform to standardize upon—whether concerning a few doors on one floor of a small office building or gates spread across a 15-square-mile major international airport—integrators need a solution that will readily scale up.

It is generally accepted that Ethernet communication technologies provide the most robust, cost-effective and easy-toinstall solutions to deploy edge devices across a wide variety of geographic conditions. Ethernet networks are, by design, modular and highly scalable. Adding network subnets can be as simple as installing a managed switch or network bridge and laying additional cable. Using internal IP addressing, the number of network-based devices that can be installed to communicate with each other is numerous.

Accessibility. Finally, and perhaps most importantly, the power of an IPaddressable system is most evident when examining its accessibility or visibility from other geographical locations. Inside the router—on the same subnet or the LAN—simply calling the internal IP address will provide instant access to the device. This is useful; however, even more valuable is the ability to use network address translation and port forwarding. This way, any IP device can be configured for easy access for external communication requirements from outside the router serving the LAN. This means, unlike closed-loop dedicated point-to-point low-voltage cabling, the IP-based system is accessible from an Internet connection anywhere in the world.

Why Go Wireless?
A wireless transmission solution is not always preferred. When transmission distances increase, and the bidding on the project becomes more competitive, it makes sense for the system integrator to consider going wireless. Here are a few of the principal factors:

Cost. Price is always an important consideration for any job and is the most significant factor in the case of government projects. Therefore, when designing a new network-based access control system, the choice must be made between the price of the materials and labor associated with dedicated cabling runs and conduit versus the cost of the Ethernetbased radio transceiver and power supply. Since long-range wireless Ethernet radio transceivers are now below $300, while the price of copper and conduit is rapidly increasing, it often makes sense to examine the wireless option for any distance greater than 50 feet in a building.

In an outdoor installation, connecting a main building to a perimeter gate access system is even more compelling. The cost of trenching conduit in place can be more than $35 per foot. A radio transmission system is almost always more cost-effective in these situations.

Due in part to rising insurance and healthcare costs, labor rates have climbed briskly over the past two decades, making labor a significant component in the overall cost of the project. The cost of labor to pull cable can be difficult to estimate—especially in older buildings—but it is likely to be greater than the few hundred dollars the wireless radio equipment costs.

Interruption in service. On the job site, the use of wireless radio transmission means that the system can be installed during regular business hours without as much concern for the interruption in service associated with pulling cable. This should be taken into account when estimating the actual total cost of the cabled solution versus that of a wireless- enabled system.

Appearance. Trenching cable outdoors will often leave a scar on the landscape. In many cases, this is hard to quantify from a cost standpoint, but certainly most professional facility managers would prefer to not have their parking lot cut through unless absolutely necessary.

Unforeseen incidents. Negotiating in-ceiling cable runs under difficult conditions—in an older building that might be contaminated with asbestos, for example—is a nightmare for all parties involved with the project. Furthermore, digging trenches on a job site to lay conduit for the network cable can be risky if the underground utilities in the area are poorly understood.