Networking

Proxim wireless systems offer affordable networking

Looking for a reasonably priced wireless solution for your home office? In this Daily Drill Down, James McPherson tests the Symphony Cordless Networking suite by Proxim. It runs on Intel's HomeRF specification. Read on to see whether it meets your needs.


While wandering through a computer mega-store the other day, I ran across a set of fairly inexpensive wireless networking devices. My curiosity was piqued and with ideas of meandering about home and office with laptop in hand, I acquired the Proxim Symphony-HRF cordless USB adapter ($100), Symphony PC card adapter ($130), and Symphony Wireless Gateway ($200). I would have liked to test one of the PCI adapters, but they seem unusually difficult to locate—even on the Internet. Proxim also sells a Symphony Wireless Modem ($250) for non-broadband locations that I did not test.

Proxim?
While Proxim has experienced some success with its RangeLAN series of wireless networking systems, it isn’t exactly a household name. Not that long ago, however, Intel bought a sizeable chunk of Proxim to expand its portfolio and help it move into non-processor markets. Intel and Proxim established the HomeRF Shared Wireless Access Protocol (SWAP) standard, which has several dozen members. Intel hooked up with long-time OEM ally Compaq to provide a corporate distribution channel, and Intel began manufacturing consumer-grade HomeRF products branded as Intel AnyPoint wireless network. To help facilitate transitions with shops using the older RangeLAN systems, the Symphony HomeRF series can be migrated by simply running the Symphony software with the RangeLAN cards. Everyone wins.

Naturally, this means that the heterogeneous networks of Symphony, RangeLAN, Compaq, and AnyPoint devices can be combined, with the only standardization being the administration software. You can somewhat avoid the historic lesson of “do not become dependent on a single vendor” with this technology if you don’t mind a little corporate inbreeding between vendors.

Technology
Like most non-IR wireless devices, HomeRF uses the 2.4-GHz band. It claims a maximum range of 150 feet with two bandwidth modes: 1.6 Mbps (200 KBps) and 0.8 Mbps (100 KBps). While the specifications are less than phenomenal, the products themselves are noticeably cheaper than the 11-Mbps Airport (IEEE802.11) wireless networks that list for around $200 per adapter and $375 for a NAT-enabled gateway.

The 2.4-GHz band is getting to be very cluttered. Many cordless phones and all microwave ovens operate on that spectrum, not to mention HomeRF and 802.11. Interference is a distinct possibility, hence the two modes of operation: a high-bandwidth mode for areas where interference is minimal and a low-bandwidth mode where signals can be duplicated to increase reliability.

Details
The gateway is a small black box, about the size of a laptop power adapter, with the standard link/activity/error lights, as shown in Figure A. The gateway also sports a standard and crossover RJ45 port to make it easy to connect to PCs or hubs. The 6-foot power cord felt a bit short, since I was trying to get as much distance as possible from the other electronics in my office—gateway server, desktop PC, 19-inch monitor, two hubs, 50W computer speakers, an entertainment system, and mini-fridge. A 6-foot power cable and 4-foot CAT5 cable just don’t do it for me.

Figure A
The gateway is a small black box.


The USB adapter is roughly the size of a deck of cards with a single, green/amber activity LED, as shown in Figure B. The device is bus-powered, cutting down the number of cables running around your desk. I think the USB cord could have been longer on this too, since the antenna works better when it is mounted higher.

Figure B
Sleek and black, the USB adapter fits in with your desk décor.


As for the PC card, shown in Figure C, the antenna is very small, extending only about half an inch from the side of the computer. The round shape helps to prevent snags, an important factor for a mobile device. I was concerned about the way the antenna snapped on. As Figure D shows, there isn’t much holding it on—one good impact could break it.

Figure C
The Proxim PC card—a card by any other name is still a PC card.


Figure D
As with many wireless cards, the antenna could be damaged easily.


Abilities
Proxim adapters are flexible devices, enabling a variety of network topologies and peer-to-peer conditions. Connection sharing, either via modem or Ethernet, is possible just with the adapters. The Symphony Maestro software package is surprisingly easy to use and understand, as you can see in Figure E. Maestro controls the client adapters and can also configure the gateway. While HomeRF devices use the same frequency and signaling, in order to be compatible with each other they must all use the same software. Maestro’s lack of a security lock on the gateway settings is disappointing.

Figure E
Using the Symphony Maestro software, you can set up your network topology.


The gateway provides for more complex solutions, including network address translation (NAT) or transparent bridging, essentially turning the wireless gateway into a hub. It provides DHCP services to clients or allows for static IP assignment. It also supports PPP over Ethernet (PPPoE), a common requirement for DSL broadband connections. I was very pleased with the gateway’s features. It can act as a full-function gateway or simply a wireless bridge, tying HomeRF clients to the LAN. The ability to change modes without downtime or reconfiguring clients is very convenient.

Security is a sticking point with me, and that is something the HomeRF devices are lacking. Unlike the packet encryption of 802.11, HomeRF doesn’t have security but uses labels instead. The software promises not to look at signals that don’t have the same label you told it to use. There may be a layer of simple encryption in there somewhere, but I couldn’t find it. If it were there, I’d expect the existence of solid data encryption to be prominently displayed on the box and in the specifications as another marketing bullet point.

Installation
The gateway installation is a snap: Plug it in to your Ethernet access point, add 110-volt power, and go. The first client adapter you get working will ask you to configure the gateway. However, the installation could have benefited from the ability to lock the configuration. Anyone with an adapter can reconfigure your system, which doesn’t make this wireless setup practical for most IT shops.

Installation of the USB adapter is a breeze. Boot your computer with the adapter plugged in, cancel the Windows Installation Wizard, then run the Symphony software. Two reboots later and a visit from my Win98 disk, and I was into the Symphony configuration. I was happy to learn that the connection test gave my signal quality an “excellent” rating. While my machine was only about 20 feet away from the base station, the signal did pass through several walls.

Being the first device on the Symphony network, the host-less gateway needed simple configurations (DNS servers, IP addresses, and determining whether it should use PPoE or DHCP). I changed it from a transparent bridge to a NAT interface and back without noting any problems. The gateway reset in about 10 seconds and did not require any actions from the clients, as long as the available IP ranges were unchanged.

Excellent technical support, dismal Web site
Installing the PC card adapter proved much more challenging. Proxim’s Web site was disappointing. The help and troubleshooting sections were reprinted manuals. Finally, I was able to determine, with the help of Proxim’s excellent technical support (they answered on the second ring!), that I had a bad card. Once I had the new card, the installation went without a snag. Proxim’s technical support made up for the uninformative Web site.

Performance
I measured throughput with the adapters and host computers located approximately 20 feet from the gateway and with two non-structural walls in between. The only active electronic devices were the local file server (without monitor), a five-port hub, the wireless gateway, and a few fluorescent lights. This is as “clean” a condition as I could expect to appear in any home office.

Single adapter
Using one adapter connected to the gateway, the data transfers for the USB adapter averaged 75–80 KBps, or 0.6–0.64 Mbps, significantly less than the claimed 1.6 Mbps, but on par for the 0.8 Mbps speeds. The PC card was even slower, with 50–55 KBps transfer speeds. This wasn’t surprising, as I had suspected the USB adapter would fare better, given that it has a larger antenna.

The connection quality was called “excellent” by the Maestro software. I believe the signal quality should have been dubbed “typical.” Moving closer to the gateway resulted in no noticeable speed improvements.

However, sustained transfer rates of 50+ KBps still greatly exceed anything a 56-KBps modem can provide and are more than adequate for single-channel ISDN. With a mere 10–20 ms of latency, they provided a zippy Web experience and did not noticeably apply lag to the Quake test. Few Web sites were able to max out the connection.

Dual adapters
This was where I had hoped the Symphony would shine. The gateway has a 10-Mbps connection and can handle eight clients, theoretically providing each of those clients with a full 1.6 Mbps of bandwidth. Since I was seeing only the low-speed mode, I expected the gateway would be able to provide each of my adapters with the paltry 75 KBps they had been drawing.

Unfortunately, running two adapters cut the transfer speeds by half. Both adapters dropped to about 35 KBps. This tells me the gateway is using the entire frequency band to support all clients simultaneously rather than using a different sub-band for each adapter. The data compression on HomeRF must be incredibly poor in comparison to 802.11 wireless, which uses the same frequency and has a theoretical bandwidth of 11 Mbps.

The moral of the story is that more is not merrier. Using eight adapters simultaneously would result in each one drawing about 8 KBps. For someone using the Wireless Modem or modem-based connection sharing, this isn’t an issue for Web surfing, but it is inconvenient for sharing files within your network. While there are few times when all eight users would be accessing data at the same time, the fact remains that there isn’t a whole lot of bandwidth.

Maximum electronic interference
The adapters were located as before—approximately 20 feet from the gateway with two non-structural walls in between. This time, however, I cranked up the juice. Our static generators consisted of a 21-inch monitor located about 18 inches from the gateway, a desktop PC, the file server and hub, a 32-inch TV, the computer and Symphony adapter, and the coup de grace—a 300-watt microwave oven about 15 feet down the hall operating on high power. I thought about scuffing my feet on the carpet and arcing into the doorknob but figured that was going too far. I expect that this scenario is more indicative of the working conditions this device should have to contend with. As expected, bandwidth and latency both suffered.

Single adapter
Total transfer speeds ranged from 45–60 KBps, with an average of 50 KBps, while latency increased somewhat to a 19 ms average. Not really that noticeable, but it could be indicative of packet loss under extreme conditions. I was rather pleased that the performance dropped only by 30 percent under this kind of stress, as I had thought the signal might be blocked entirely.

Dual adapter
Running two adapters reduced transfer speeds to 20–25 KBps as expected from the low-interference tests. Both adapters performed as before, reaffirming the fact that at transfer rates below 50 KBps, the increased antenna size of the USB adapter does not give it an advantage.

Again, these speeds and response times are far beyond what you would see with a 56-KB modem. An office with single-channel ISDN really wouldn’t notice much performance loss when it comes to accessing the Internet, but file swapping would be inconvenient.

Range test
The Symphony system lists a maximum range of 150 feet, far exceeding the size of my office. So I took a hike around the building. At 100 feet, the maximum range at which I still had line of sight to my office, the connection appeared undiminished. Wandering behind a nearby building brought the connection to a crawl but not, I should emphasize, a dead stop. I occasionally had to retry or reload a page, but the connection never dropped entirely despite being 100 feet, three brick exterior walls, at least two fire walls, and unknown internal walls away.

Final grades
The gateway was a wonder of Plug and Play technology that just plain worked, deserving an A+. I give the Maestro software an A+ for ease of use and features, but a C– for security. The USB adapter receives a solid B as a result of its simple installation process and reasonably acceptable performance. Because of the dud PC card and the lower bandwidth, the Symphony Cordless PC card receives a C+.

Proxim gets mixed reviews for support; the Web site earns a C, while the top-notch phone support warrants an A, for a total support average of B.

In general, the current incarnation of HomeRF is fairly slow with a peak bandwidth of 1.6 Mbps (I never saw more than half that). Even if 802.11 components cost twice as much, their 11-Mbps bandwidth (nearly seven times as much as HomeRF) seems much more attractive. The range of the HomeRF does live up to expectations, however.

The Symphony HomeRF system is appropriate where bandwidth is not a priority. Given that the broadcasts are unencrypted, they aren’t really appropriate for use with sensitive material. For a home office, training areas, or home use, the HomeRF system provides a cost-effective, easy-to-implement solution without the hassle of wires. But if you need CAT-5 speed without the wire, you should keep looking.

Conclusion
In this Daily Drill Down, I showed you how to install, configure, and set up HomeRF, and took each component on a test drive. I concluded with a recommendation about whether HomeRF components—and the Symphony suite of adapters—are right for your home office.
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