Cutting the Cord
The latest solution for improving productivity and enhancing efficiency is wireless technology. Despite the current fascination, material handling managers would do well to explore this solution thoroughly before rushing to untether.
By Leslie Langnau, senior technology editor
Faster order entry. Better accuracy. Paperless transactions. Lower costs. There’s a lot of promise to wireless.
However, while installations are going in, the technology is still young and evolving. It’s not a matter of “plug-n-play.” Here’s what’s happening: Work in developing standards for the two main wireless systems, 802.11b and Bluetooth, is ongoing. Security – how much and even whether to have it – can be a big issue. Many security features have proprietary elements, compromising compatibility. And throughput promises are just that – actual rates are about half of what’s promised.
If you keep in mind the history of industrial bus systems, like DeviceNet and Profibus, you’ll have a fairly good idea of what to expect with wireless while development goes on.
Should you cut the cables?
Wireless in the distribution center is not new; 900 MHz systems have been in place for many years. Some facilities are still using UHF radio.
What’s exciting people today is the prospect of higher transmission speeds. Eleven megabits per second (Mbps) is tantalizing, with 54 Mbps even better and not far from commercial availability. Before you buy, however, determine what you really need. For one thing, you won’t actually transmit data at 11 Mbps. That number includes overhead and error checking code that goes with the data through the network. Thus, the actual data throughput rate for the 11 Mbps networks is closer to 5 or 6 Mbps.
Secondly, few distribution center applications need a high transmission rate. “Most centers doing pick-and- place have very little data traffic,” says Yangmin Shen, senior manager, Wireless Technical Marketing, Symbol Technologies, “so they don’t really get any benefit out of a faster network.” That’s why older systems operating at 9,600 bps are still viable for many facilities.
More bandwidth, such as that promised for 54 Mbps, is no guarantee of faster “speed.” Again, overhead, security algorithms and other network features significantly cut speed. “You can design a wireless system to provide high rates,” says Jim Bostwick, senior systems consultant, Intermec, “but it will double or triple the amount of equipment you need to install to achieve it.” And that will double and triple the system cost.
Data transmission speed should not be the main reason for going wireless. Consider other benefits possible with this technology. For example, many claim it will spread information faster and streamline processes, but then, all new technologies make that claim.
Probably one of the more important benefits from wireless is the ability to reduce errors and increase inventory accuracy, which it does by reducing paper work.
“Wireless lets you go from a paper-based system to paperless,” says Bostwick. “It tells you where to go next and what to pick. And the instructions may be complex or fairly simple.”
Another reason is that “Wireless is an enabling technology,” says Shen. “You can’t have guys on lift trucks using a wired system. Wireless enabled the use of trucks in picking. And new capabilities are coming in terms of real-time location systems that use transponders or transmitters to locate parts to an accuracy of 10 feet. Other systems will have better location capabilities. All of which will be integrated into wireless networks.”
Plus, you can consolidate multiple communication and tracking systems. “We’re on the cusp of replacing that radio,” adds Shen.
Freedom of movement
Material handling managers can work through their WMS vendors to install wireless systems. Many advanced WMS programs include wireless features and will contract out the actual installation work.
The WMS software combined with wireless communication offers an advantage beyond simple communication to lift truck drivers, pickers and other operators on picking, receiving and put-away activities. It offers excellent coordination. When a hot order comes in, for example, the software can direct all pickers to fulfill that order. It can direct wave picking. It can implement multitasking picking for better efficiency, instructing an operator to pick the nearest item because it will be needed soon, even though it doesn’t fulfill the immediate order. “With a paper-based system,” says Bostwick, “this is hard. But a good WMS system will multitask users’ time to best advantage.”
Another perk of wireless and WMS is the ability to do continual cycle counting. When times are slow, the software can direct operators to do a cycle count of a specific area, which it then uses to update its database. In this way, inventory is always up to date. Operators no longer must do a physical inventory; instead they do cycle counting.
Another use of wireless is for field people to check inventory status, place orders, and track accounts. However, connecting to Web sites and the Internet is still a problem area for wireless technology. Some say it’s worthless to connect to the Internet because of all the transmission, data downloading and compatibility and security issues. The industry is working on changing this, but be aware it’s not ready yet.
The main suspects
The 802.11b is the standard for interoperability of unlicensed 2.45 GHz wireless local area networks (LANs) and is compatible with most Ethernet cable-based networks. It’s supposed to ensure that radios that comply with the standard will smoothly interoperate.
Bluetooth is a 2.45 GHz network originally designed for personal area networks, those that involve an individual’s personal computer and companion peripherals, such as personal data units, cell phones, plug-ins, etc.
Devices using Bluetooth are slowly becoming available, but not at the pace the industry expected. Part of the problem is that the price of microprocessors implementing the protocol are still too expensive; they cost about $15 to $25 each. When the price drops to $5, more Bluetooth devices will be available.
Contrary to the hype, these networks don’t compete with each other, or with the newer versions of 802.11. The structural formats of these networks is similar, both use wireless stations and fixed access points. Access points provide a bridge between the wireless points and the network.
The competition angle, however, primarily involves costs. If you look at Bluetooth strictly from a cost viewpoint, it’s less expensive than 802.11b. That’s partly because Bluetooth has a much shorter transmission range than 802.11b.
802.11b devices can transmit data about 1,000 feet before they need to reach another access point or station. Bluetooth’s range is about 30 feet.
Both are considered local area networks. For these networks, that means data typically move within the walls of a distribution center, room, or within the walls of a large building. By contrast, a wide area network can send data beyond the walls. The majority of 802.11b installations in distribution centers and DCs have transmissions that stay in the walls. Problems of signal clutter because “everyone is using the 2.45 band” are minimal to non-existent unless everyone in your facility uses a cell phone, PDA, several scanners, and so on. Security is less of an issue too, as it’s primarily when your data go outside the walls that you need to worry about data integrity.
Both technologies can even be used together in an application. UPS, for example, is doing this to help package sorters at its Chicago distribution center work more efficiently. The employees will wear a Motorola computer terminal around their waist. They will use a Symbol Technologies cordless ring scanner to scan incoming packages.
The ring scanner uses Bluetooth technology. It scans package bar codes and sends the data to the terminal on an employees’ belt. The terminal, which can hold about 640 K of data, uses 802.11b to send the data to the WMS system. Thus, employees are unhampered by cabling, giving them the mobility they need in the large facility.
The terminal uses both Bluetooth and 802.11b protocols. If both networks attempt to transmit simultaneously, they could cancel each other out. To prevent this, each network transmits its data at separate times. Research indicates that a distance of one meter between devices can cut or eliminate transmission problems.
There’s a debate on how secure wireless systems need to be because they tend to be open and susceptible to hacking. Actually, security depends on the application. Few distribution centers are transmitting critical data, so security needs may be low. Plus, the wireless devices themselves are generally not the keepers of sensitive information. Instead, they simply transmit data to another source, like a control or central database. Thus, security, if it’s needed, is only needed during data transmission.
“Another factor, though,” adds Shen, “is that security is a layer of administration and inconvenience. And there’s a cost associated with these. Companies must weigh the costs versus the need.”
That said, however, security should not be ignored. “You need firewalls, at least,” says Bostwick. “Especially if the wireless system ties into the corporate mainframe. The vulnerable points are when data go outside the building “
Agrees Shen, “At the very least, turn on WEP [the Wired Equivalent Privacy algorithm], regardless of its flaws. If you don’t want your car stolen, you remove your keys. Without WEP, you’re almost advertising, ‘please steal me.’ And what people will steal is access to your network service provider. This can slow your throughput rates.”
In addition, the world has changed. It might be far-fetched to think terrorists might somehow use your distribution center for their goals, but then, a lot of scenarios seemed far-fetched before September 11, 2001.
The Wired Equivalent Privacy, or WEP, protocol is built into 802.11b. This algorithm was not meant to provide end-to-end security, and has already been “cracked and hacked” in several showy demonstrations. Part of the problem is that all devices and access points use the same key to encrypt and decrypt data. But it will keep out amateur hackers, as long as it’s used.
That’s part of the problem with 802.11b security – many are not taking advantage of it. The rush to install has left a large number of installations wide open to anyone with a $100 network interface card, a PC and some free downloadable software.
You can install additional security to this and other wireless networks. However, be aware that the more you add to a system, the more you will slow the throughput rate.
Security is a system issue. Not only must you secure access points; you must also secure the devices that connect to the access points.
Solutions range from end-to-end encryption, frequently changing passwords and encryption keys to virtual private networks. Watch encryption, though. Some algorithms make your systems proprietary, hampering compatibility. If your data are sensitive, treat them more carefully than you do Internet data. A determined hacker will probably get in anyway, but you don’t have to be an easy mark. And there is software available that will tell you if something suspicious is happening to your network.
Security is a concern for another reason. Most breaches still occur within a company from disgruntled employees, and they often occur as denial of service attacks. This means your servers cannot accept orders or send messages out because they are too busy handling a flood of other message packets that tie up access. The end result can be a loss of business because your customers can’t reach you.
Because of the current economic conditions, some experts advise that companies ought to wait a while longer before implementing wireless solutions. Several wireless products, for example, are in their third generation of development in this year alone! So if you’re looking to cut costs, one way may be to postpone wireless until the technology is more stable. It’s crucial to determine what you’ll actually gain from this technology before you go ahead.
However, once you’ve decided to go wireless, how can you avoid a waste of time and money? Here are several tips from integrators.
• Do a site survey and make sure you have professionals do it. Identify the areas that need wireless coverage. Note if you still plan to use RF systems. Examine existing electrical cabinets and network systems, including their hubs and switches, for compatibility problems. Can the current system support a 100 Mbps backbone? Make sure the existing system is not experiencing too many collisions. If it is, it’s time to upgrade that network.
• Make sure you have the needed infrastructure, such as an Ethernet backbone. Communications need to be viewed as crucial to your business. “Try to keep the backbone itself to a single vendor,” advises Bostwick. “Hand-off between access points can be a problem, especially if you have a backbone with different vendors’ access points.”
• Determine what functions the wireless network will handle.
• Wireless lets you be on-line to your database from any location you have coverage in. However, you need software to handle this load. Software will probably be the largest cost. “Wireless hardware cost is always 10 percent or less of total system cost,” says Bostwick.
• Compatibility can be an issue, even among supposedly 802.11b-compliant devices. “Various vendors’ radios will work together, as long as they use direct sequencing transmission format,” says Bostwick. “A direct-sequence 802.11 system won’t talk to a frequency-hopper system, though.”
• Keep in mind that development of these wireless networks is still ongoing. Carefully weigh the benefits of installing wireless now versus waiting for the “next big thing.”
• Use of PDAs can be great, but remember that these devices can’t easily display a lot of text and their ergonomics isn’t good for typing.
• Wireless affects who has access to data, thereby changing management and organizational structures. Resolve issues of who can have access to sensitive customer data before you install a wireless system. Such changes can be great for customer service, but an issue for management.
• Remember that wireless is not a cure-all. SCF
For more information
The following companies offer wireless networking equipment and components:
Axcess Inc., www.axcessinc.com
Comtrol Corp., www.comtrol.com
Crossbow Technology Inc., www.xbow.com
LXE Inc., www.lxe.com
Microwave Data Systems Inc., www.microwavedata.com
Psion Teklogix, www.psionteklogix.com
Symbol Technologies Inc., www.symbol.com
TDK Corp., www.tdkca.com
Zebra Technologies Corp., www.zebra.com
To improve control over all inventory, warehousing and distribution operations, Volkswagen Group UK Ltd and TNT Logistics plan to install a Psion Teklogix wireless LAN solution across a new parts distribution warehouse based in Dordon, Warwickshire, UK. The system will allow two-way, real-time data communication between mobile workers and the central LIS Dispatcher Warehouse Management System.
“It will help us better our overall service to our retailer network and customers because it will prioritize tasks to handle urgent distribution requests,” said Andy Williams, parts logistics manager, Volkswagen Group, “plus it will improve picking accuracy.”
“The success of the operation depends on 100 percent RF scanning within the new warehouse, working through the warehouse management system,” said Rob Elton, account director of TNT Logistics.
The workers will use Teklogix 7035 and 7025 hand-held and 8255 vehicle-mount wireless terminals for the orderpicking, replenishment and put-away tasks.
Social Security Saves Money
Before installing a wireless automated data collection system and a warehouse management system, the U.S. Social Security Administration manually picked and shipped some 240,000 items to its 3,500 customer locations. The items included forms, toner cartridges, publications and other office supplies.
Unfortunately, backlogs often had 10,000 to 12,000 items and it would take 30 to 45 days to process. Emergency orders were processed in seven to 10 days. To speed up delivery, the administration decided to take its order fulfillment system paperless.
Using a wireless backbone, access points, hand-held computers and bar code printers from Intermec and a Radio Beacon WMS installed by Data Technology Software Integration Ltd., the administration is seeing savings of $620,000 per year. Plus, the backlog is gone. Orders come in by e-mail, telephone or fax and are processed in an average of three days. Emergency orders are processed the same day.
Wireless hand-held terminals work well where the goal is to gather data. They help ensure repetitive and simple tasks, like picking, packing and put-away are completed correctly.
Terminals on lift trucks and other vehicles typically direct users to do specific tasks. They too track task accuracy.
Personal Data Assistants (PDAs) may not be the best approach for scanning-intensive applications. They do offer employees mobility, however. Plus, when you need access to more information, they can help.
Wearable and hands-free devices, of course, free hands for other tasks. They work well in scanning intensive applications.