Residential Spectrum Management: The Manufacturer’s Role

David A. Case

Manufacturers need to take a greater part in helping consumers address wireless interference in the home.

Figure 1. Schematic of the risk management process presented in ISO 14971:2000 (click to enlarge).

Take a look at any Sunday newspaper’s advertising section for stores that sell electronics, and it is clear that wireless devices are everywhere. Visit these stores and listen to the salespeople selling wireless local-area networks (WLANs), cordless phones, and all else wireless to often-naive consumers.

What salespeople fail to tell consumers is that before consumers buy the latest wireless gadget, they should make sure that it will function properly in their home environment. For an unknowing consumer, it can be frustrating to buy a microwave, a 2.4 GHz cordless phone, a 2.4 GHz video transfer system, and a 2.4 GHz WLAN, and then find that only some work error-free once installed at home.

Manufacturers of consumer products have done little to address the issue of residential spectrum management. This article presents an overview of the interference caused by the proliferation of wireless devices in the home. Moreover, it addresses the overriding issue of manufacturer responsibility and what manufacturers can do to address the problem. Although this article does not approach this problem as a quality issue, technically it can be seen as one. By addressing this issue, manufacturers may find the number of returned items reduced accordingly.

Worldwide Spectrum Management

Most consumers are unaware of spectrum issues, particularly interference from devices using the same frequency. Consumers only hear a salesperson say that the 2.4 GHz phone is the best to get, and so they buy it. It’s not until they heat up some leftovers in the microwave that they discover a problem. In this case, because the microwave is a Part 18 device that is interfering with a Part 15 device, the Federal Communications Commission (FCC) will not step in, and manufacturers are in the clear so long as they have met the applicable regulations.

Spectrum management is currently done on several levels: national, regional, and, of course, global. In the United States, FCC and the National Telecommunications Information Administration (NTIA) address the government spectrum issues. Regional spectrum management is done by groups such as the Inter-American Telecommunications Commission (CITEL) and the Conference of European Postal and Telecommunications (CEPT). The International Telecommunication Union—Radiocommunication sector (ITU-R) addresses global harmonization of the frequency bands.

However, good spectrum management stops at the consumer’s doorstep. The ITU-R lists the 2.4 GHz band as an industry, scientific, and medical (ISM) band. Most national administrations allow license-exempt devices to operate in these bands on a noninterference basis. The most popular band for these products is 2.4 GHz. Devices such as WLAN, Bluetooth, cordless phones, wireless video transfer, and wireless cameras operate in this band. And, because it is an ISM band, microwave ovens operate there as well.

Home Spectrum Management

Manufacturers often take the view that as long as their products are certified, interference is the other guy’s problem. What most manufacturers fail to acknowledge is that the consumer ultimately ends up with the problem. Unfortunately, consumers don’t necessarily know why it won’t work, just that it doesn’t. These devices often end up as returns or consumer complaints.

From a compliance engineer’s point of view, however, interference is the one issue that is never fully addressed. Those in the industry who understand this situation choose wireless devices carefully, such as opting for cordless phones that operate at 900 MHz or lower to avoid interfering with the WLAN. Other tips include making sure that the wireless access point is not located next to the microwave oven. However, this information is rarely given to consumers.

Consumers have no spectrum manager in their home to address frequency-use assignments. Although some would like to say it is an FCC issue, FCC does not handle interference issues or spectrum management for individual consumers.

Consumer Education

The only solution at this time is better consumer education. And, the responsibility should rest with manufacturers. Retail salespeople are not familiar with what products will operate together and which ones need to be set up to avoid problems. Manufacturers should inform consumers that the bands are being shared with other systems and that sometimes these devices may not function well with each other when both are operating in the same band.

A number of things can be done up front to avoid some of these problems. As part of product development, manufacturers should include warnings in product manuals. In particular, manuals should warn consumers about interference potential for the device. This warning should be specific. It should address interoperability with competitors’ versions of the product as well as with other types of devices that share the band.

Conclusion

Manufacturers can no longer afford to leave spectrum management up to everyone else. With so many wireless devices now available, the onus must fall on the manufacturers to help consumers manage them. The problem will continue to get worse. It may soon warrant review from groups such as the IEEE EMC Society or the Consumer Engineering Association.

David A. Case, NCE, NCT, is a senior regulatory engineer for Cisco Systems Inc. (Richfield, OH). He is a member of the staff of the Corporate Compliance EMC Standards and Operations Group. He is responsible for addressing radio compliance regulations for Cisco and has been a member of U.S. delegations addressing CITEL and World Radio Conference issues. He serves on numerous technical committees as well as being a member of the Compliance Engineering editorial advisory board. He can be reached at 330-523-2139 or at davecase@cisco.com.