Posted Laptop and Desktop Hardware, WiFi Wireless Networking, Techie News on Tuesday, May 23rd, 2006.
MIT’s Media Lab demo’d prototypes of their $100 laptops today, May 23rd. Here’s a photo gallery of the OLPC $100 laptops that are targeted at children in developing nations …and they’re some sweet little machines. Putting aside the issues of black- and gray-market sales of these systems the whole rest of the project is incredibly well thought out.
Our “custom-configured” Windows world has a lot to learn from the design of these little machines. By standardizing both hardware and software configurations they’ve managed to implement 802.11 wireless-mesh networking and a minimal-IT-required Linux system. Should the operating system or software get messed up or infected (…however unlikely that is on Linux) - the whole system can be reimaged without worries of data loss. How do they manage to store data without any expensive servers? Each machine only has 512MB of FlashRAM/non-volatile storage and is designed to share data via a community (the local mesh, I think) wiki system. Sounds a little like Windows roaming profiles, except without the bloat and ability for users to still store data on the local drive; also way ahead of the server-centric network PC/thin client systems encouraged by Oracle, Citrix, Wyse and many hardware manufacturers.
The whole project is well documented at laptop.org, so take a look for yourself.
Posted Laptop and Desktop Hardware, WiFi Wireless Networking on Monday, May 1st, 2006.
Wireless USB and PCMCIA (PC Card) adapters now available are very similar in performance. There is little reason, other than personal preference to choose one over the other. There is good reason to choose a laptop with a built-in Wi-Fi adapter over an external option, so if you’re considering saving a few dollars by getting a USB or PC Card adapter instead - don’t.
Wireless range is directly related to the amount of power sent through the antenna. Since laptop devices usually have less powerful antennas than base stations plugged into the wall, early reports of inferior range in USB wireless devices were because the USB bus supplied less power (ref. #1 below) than the PC Card bus (ref. #2 below). Now that the antennas on both types of devices are very similar and most Windows XP drivers allow Windows to manage the power used by the wireless device automatically it’s rare for either USB or PC Card devices to either be run at full power or for one type to have a better range than the other.
An internal wi-fi card is a big improvement over the above options, because the antenna are much larger and more sensitive. Most laptops with internal wireless devices have an antenna wire in around the outside edge of the screen, making a big improvement over any external options, regardless of power output.
Also, PC Card technology has more power-saving modes (handled automatically by the PC Card controller, ref. #2 below) than USB does. Before Windows XP started to manage power via the driver - PC Card wireless devices went into low-power mode more often and depleted the battery less than USB devices did. Now there is little to no noticable difference in battery use by either device. …although, when a laptop is put to sleep either device will continue to consume a small amount of battery power if it is left in the laptop. Since USB has slightly better hot-plug support (ie: it can be removed and reinserted without causing errors on the PC) it is usually easier to remove it when putting the PC to sleep. …so, maybe USB is the way to go for you.
Note on Wireless-B, -G, and -N: It’s worth paying attention to the type of communication that a wireless device uses. All Wi-Fi devices “speak” some form of the 802.11 “language”. The letter after the 802.11 indicates the “flavor” of the language - and some are much better/faster than the other flavors. 802.11G deals with radio “noise” (like microwaves and cordless phones) better than 802.11B. Also, if you can find a “pre-N” (pre-802.11N) wireless device choose it (if it’s in your budget). The pre-N technology may not work with the final 802.11N, but all N-flavor devices have much better antennas than the B or G flavors. So, the “best” flavor is “pre-N”, followed by “G”, and then by “B”.
References:
- http://www.usb-port.com/usb_faq.html - USB supplies 500mA @ 5V
- http://www.pcmcia.org/pccard.htm - PC Card supplies 660mA @ 5V, 1000mA @ 3.3V
Posted Windows Desktop Fixes, WiFi Wireless Networking on Thursday, September 1st, 2005.
In recent months new NetGear RangeMax and Linksys SRX wireless adapters have been configured to require that respective manufacturer’s wireless management utility to be installed with the drivers. This is a problem because both managment tools cause errors when running on a Windows XP PC with Service Pack 2 installed. There are even several reviews of the RangeMax PCI adapter on Amazon
The fix…
Simple. First, don’t uninstall the NetGear or Linksys software. That will probably remove the drivers for the card too. Instead, disable the NetGear or Linksys configuration software by pulling them from the Programs menu’s Startup folder and the registry startup items (Open regedit > then HKLM/Software/Microsoft/Windows/CurrentVersion/Run/ > and delete any references to the software). Then just follow the steps in this Microsoft Knowledge Base article to enable the Wireless Zero Config. (WZC) service: “Error Message in Wireless Network Setup Wizard…“. That’s it, no reboot required, the Windows WZC should pop up a message about detected networks in a few seconds.
Posted WiFi Wireless Networking on Tuesday, June 7th, 2005.
Review Summary:
Linksys manufactures several models of antennas to improve the range of 802.11b and 802.11g, also called Wireless-B and Wireless-G, network connections. The HGA7S model is a single antenna designed to replace the removable antennas on most brands of PCI-bus wireless adapters and some access points. Raw specifications suggest that wireless range should be improved about 2.6x normal by adding this antenna to the networking setup. Due to noise and signal degradation playing a large role in an office setting, the signal strength improved enough to add only 25-30% (about 1.3x normal) to the effective range of consumer grade access points. Using the separate antenna stands sold by Linksys (model AS1SMA) the antenna could be relocated away from walls and corners, making this antenna and the stand a moderately effective solution to signal cancellation. There are more effective options for improving wireless range, although none is quite as inexpensive as the Linksys High Gain antennas (currently selling for only $36.05 on Amazon.com).
Detailed Review:
The biggest advantage of this antenna over other range-increasing devices is the easy installation. The original, OEM, antenna can be unscrewed and this antenna attached even with the WiFi card or access point turned on. Waiting a minute for the card or access point to reconnect to the opposite end of the WiFi connection is required after a powered-on swap. Just make sure there is enough additional overhead space for this antenna. It is 11.5-inches long and, to be most effective, it should be vertical and not tilted (omni-directional antennas, like both this and OEM 2.2 dBi ones, are most effective when placed vertically). Indoors an omni-directional antenna should be tilted only in situations where a wall or angled surface causes signal reflection noise. Without enough overhead space the Linksys AS1SMA antenna stand can be purchased separately and used to relocate the antenna a short distance from the SMA connector on the PCI-card or access point. This additional freedom of movement proved helpful in improving the wireless signal for PCs that were placed in angled corners or inside enclosed cabinets.
The low cost of this antenna is a small advantage over other range-increasing devices. It is a quick fix for spotty wireless connections, but because adding it yielded only limited range increases in both office and home it isn’t a solution when no signal at all reaches an enclosed or distant area. In indoor situations enclosed areas may have too much signal noise for any antenna to help. Distant areas in indoor situations can be completely shielded by walls and have no signal to amplify. For such distant or enclosed areas more expensive solutions like the Belkin F5D7130 in repeater-mode or NetGear’s RangeMax Access Point
According to specifications the HGA7S antenna has a peak gain of 7 dBi. Most OEM antennas included with wireless access points and PCI-bus cards only have a peak gain of 2.2 dBi. The range of an antenna in an open field with no other interference should double about every +3 dBi. So, in an open field the HGA7S antenna adds about 4.8 dBi of gain, and +4.8 dBi/3 dBi per 2x range = 2.6x normal range. Unfortunately our tests in indoor environments resulted in about 1.2-1.5x the pre-HGA7S range.
Before purchasing the HGA7S, several things to check on existing equipment:
- Does the device to be upgraded have a removable antenna with an SMA connector?
- Is the existing device either 802.11b or 802.11g? This antenna will not work with new 802.11n or older 802.11a equipment.
- Does the existing connection fail occasionally or completely not connect? A wireless signal repeater or Wireless-N/MiMo access points are more likely to be effective in greatly increasing range.
Posted WiFi Wireless Networking on Saturday, May 14th, 2005.
A client of mine has a (very) large house and because of a long-ago remodel the only cable hookup into the house is in a far corner of the downstairs - while there are three PCs upstairs so the kids can do their homework (aka: instant messaging endlessly). To get a wireless signal through four walls, a floor, and 200 ft. of space, instead of attaching antennaes to the existing Linksys wireless router and every wireless card in the house, I decided to try an active signal repeater. An active repeater
With very few options on the market the Belkin F5D7130 access point
The installation and setup process to configure the unit as a repeater was simple. I plugged it in, assigned an IP on my client’s subnet (although that isn’t even necessary) through the straighforward web interface, and then added the MAC address of the existing access point. A yell from upstairs not more than 5 minutes after I had started to configure the device let me know it was working …already.
Despite a limited feature-set and a simplistic web interface, the F5D7130 router is a 5 out of 5 when using it as a repeater. I haven’t seen a setup this easy or fast on any wireless access point yet; normally something doesn’t work right or needs to be double-checked. Like all wireless devices this is vulnerable to hacking, even if it’s not the primary access pint on a network, be sure to configure WEP encryption & update the firmware to support WPA. Just one warning , this device will strengthen Wireless B, G and N singals, but with only one antenna it doesn’t support the full pre-N/MIMO wireless range. Screenshots and one-page setup instructions can be found at Tom’s Hardware.