You have several options for how to rig your car PC for wireless Internet connectivity so you can surf the Web, download email, or transfer files while on the go.
In the old days, there were only a few ways to get online wirelessly, each of them slow and expensive. Recently, that has all changed. This hack will help you understand your options and choose your wireless connectivity solution.
In the era of analog cell phones, you could pay upwards of a dollar per minute for a modem connection of between 2,400 and 9,600 bits per second (i.e., up to 9.6 kbps). Not only was the connection slow, but it usually took a minute or so to connect as well, making even a failed attempt at getting online a costly affair. The conversion to digital cell phone standards opened the door to faster connect times, but for a long time it did nothing to increase connection speeds, which were still pegged at 9600 bits per second.
For many years the U.S. market had its own handful of cell phone standards, including analog and early transitional digital standards, while Europe had standardized on GSM (Global System for Mobiles). In the last five years GSM has gained popularity in the U.S. market (through T-Mobile, AT&T, and Cingular), and now the two major standards in the United States are GSM and CDMA (Code Division Multiple Access, describing how the signals travel).
Both GSM and CDMA have basic digital transfer and fax capabilities, being digital protocols. But these so-called 2G (second-generation) cellular standards maxout at modem speeds (i.e., up to around 50 kbps). Higher-speed data protocols build upon these standards.
The broad set of aims for wireless evolution with all the features anyone could want falls in the scope of 3G (the third-generation wireless protocol; see http://www.3gpp.org for GSM and http://www.3gpp2.org for CDMA). What has been deployed so far is only part of this grand vision, and these transitional standards have been dubbed 2.5G.
In addition to the GSM and CDMA standards, there are a number of technologies that seek to push data-transfer speeds into the broadband range. These include GPRS, EDGE, 1xRTT, and EVDO.
At the bottom of the speed barrel is GPRS (General Packet Radio Service). While the top speed of GPRS is theoretically over 150 kbps, in practice it consistently offers only the speed of a 28.8-kbps modem. However, unlike with traditional dial-up-over-cellular solutions, the connection times with GPRS are so short as to seem instant, and the connections are very durable, handling the transition between cell towers well so that your connection is not dropped.
GPRS service is relatively cheap—T-Mobile provides it for an additional $20 per month on your existing Bluetooth phone or for $30 per month on a PC card for unlimited data transfer. It has a very wide coverage range (pretty much anywhere you get GSM cellular reception, GPRS will work), and you can use it to surf the Web (slowly) on your car PC. For general telemetry applications, it is a cheap, solid solution.
T-Mobile and Cingular (which has absorbed AT&T) provide GPRS service in the U.S. market. There are two major ways to use it. One way is to get a dedicated GPRS PC card. T-Mobile provides a Sony Ericsson combination WiFi and GPRS card, so that you can transition between a T-Mobile WiFi hotspot and their GPRS service. The other way is over a Bluetooth connection to your mobile phone.
EDGE (Enhanced Data Rates for GSM Evolution) is an upgrade path for GPRS speeds. It has a theoretical maximum connection speed of 128 kbps or 384 kbps, depending on the configuration. In the U.S. it actually provides about 60–80 kbps. Since Cingular recently absorbed AT&T, Cingular and T-Mobile are now the two leading GSM phone service providers in the U.S. Right now, Cingular/AT&T has EDGE, and T-Mobile is about to deploy it.
EDGE networking works in the same way as GPRS. You can use either Bluetooth or a PC card to get it in your machine, and EDGE access cards are backward-compatible with GPRS networks, so you get wide coverage. In my experience, it delivers a sort of choppy enhancement to normal GPRS. When fetching large emails or downloading files, the raw throughput is fantastic. However, the latency of the connection is high, and while you're surfing the Web this can mean lots of failed connections or 20-second waits while switching towers. Once established, though, EDGE connections, like GPRS, are very solid.
As this list of confusing acronyms shows, the marketing hasn't really caught up with the technology. Within the CDMA standards used by Verizon and Sprint, the terms 1xRTT (1 pair of channels, Radio Transmission Technology), W-CDMA (Wideband-CDMA), and 1xEVDO or just EVDO (1 pair of channels, Evolution, Data Only) describe the new higher-bandwidth data protocols that are available. While 1xRTT only goes up to 144 kbps, EVDO operates at up to 25 times the bandwidth of traditional CDMA, with a theoretical maximum connection speed of 2 Mbps and an average of between 300 kbps and 500 kbps. The upload speeds are considerably slower, at 60–80 kbps.
Sprint provides the bandwidth for the very popular Treo (Palm OS) hand-helds, but their network, as of this writing, only offers speeds of up to 144 kbps, and their pricing is not that competitive. Verizon, on the other hand, offers the fastest flat-fee bandwidth available. Their NationalAccess plan offers only modest speeds of 40–60 kbps, but it lives up to its name with coast-to-coast availability in the U.S. Verizon's BroadbandAccess, however, provides what you an truly call broadband speed at 300–500 kbps, and it is available in a dozen major city markets. Reviews I have read report sustained speeds as high as 800 kbps, with spikes of up to 2 Mbps. At this speed, live audio streaming (e.g., via http://www.live365.com) and even video streaming are possible.
WiFi is the consumer marketing term for a group of wireless networking technologies that you must have heard of by now. Most WiFi signals run at the frequency of 2.4 GHz. WiFi speeds range from 11 Mbps (802.11b) to 54 Mbps (802.11g), and newer standards run into the 100-Mbps range. However, because of protocol overhead, interference, and bandwidth sharing, you are guaranteed to get less than half of the theoretical throughput in the best case.
WiFi was not originally designed as a wide area networking protocol, but the emergence of open wireless hotspots and the workability of WiFi at driving speeds have made it a viable option for mobile Internet access. Mind you, this does not mean that you can drive down any highway and have guaranteed high-speed WiFi access—WiFi will not let your passengers surf the Web unless you are near a hotspot, or driving slowly in rush hour through a WiFi-saturated neighborhood.
What it does mean is that a number of vendors, such as T-Mobile (http://www.tmobile.com), have installed WiFi access points at many popular retail locations (such as Starbucks), and that the same WiFi adapter you use to access the Internet at home and work can seamlessly "roam" onto these networks. For uses that can be batched, such as downloading email and news feeds [Hack #21] , synchronizing MP3 collections [Hack #64] , or uploading GPS logs to a web site [Hack #67] , this high-bandwidth but intermittent connectivity works perfectly.
To connect to one of these mobile phone wireless networks, you'll need a new network card. Your existing WiFi cards won't work on the 3G networks (although your Bluetooth-equipped laptop can communicate with these networks through a Bluetooth-equipped mobile phone).
Normally, wireless PCMCIA cards are sold as part of a service contract (like mobile phones) by the wireless provider. To get a better picture of all the available wireless options, try looking up the hardware first, rather than going directly to the service providers.
Sierra Wireless (http://www.sierrawireless.com) is one of the best starting points, because they make wireless PCMCIA cards (their AirCard series) for almost all of the major wireless networks. Another good hardware provider is Novatel Wireless (http://www.novatelwireless.com), with their Merlin series of wireless cards.
You can improve the reception of these cards by using an external antenna. The best vendor I've found for a wide array of antenna products is HyperLink Technologies (http://www.hyperlinktech.com). My own company, CarBot, buys all its car-mount WiFi antennas from HyperLink, and we've been very happy with the reception using their 5dB antennas. (Decibels, or dB, are a measure of signal strength; more is better.)
Because of a lack of early standards, there are literally dozens of possible connectors for WiFi antennas. HyperLink takes care of that, because they provide pigtails (short wire adapters) that convert any WiFi card or access point you have into an N-female ending, which can then be connected to any of their antennas.
HyperLink's 19" pigtails also provide stress relief for the tiny connector needed for the most popular PCMCIA WiFi cards (see Figure 6-1). Wavelan, which became Orinoco, which became Proxim (http://www.proxim.com), makes the most popular and best-supported WiFi cards. Most of their 802. 11b and 802.11g cards come with an antenna port, which is a rare thing for PCMCIA cards.
Although you can get online with a PCMCIA card, another way to do it is by connecting through a Bluetooth-capable phone [Hack #63] , which you may already own. The cool thing about the Bluetooth modem feature is that it works just as fast as a PCMCIA card and connects very rapidly. It only takes a few seconds to get connected, and your phone can be sitting anywhere—you don't have to point it at the computer or even take it out of your pocket—although I usually put it on the dashboard or clip it to the ceiling so I ensure that it has a good signal.
I've traveled from Los Angeles to San Jose, California via Interstate 5 and maintained a GPRS (modem speed, about 20 kbps) connection most of the way, with some interruptions in the Grapevine (naturally). While going through a canyon on the 152 (which takes you inland from Interstate 5 to the 101 Freeway near San Jose), I lost my connection completely for an hour; however, my mobile phone didn't work in that canyon either.
Once I upgraded to my Nokia 6620 with EDGE (60–80 kbps), I continued testing. When I repeated my LA-to-San Jose mobile connectivity test, the EDGE connection lasted just as durably, with the same Grapevine and Route 152 interruptions. One of my passengers was downloading programs and doing extensive Google searching while we went at freeway speeds up the Interstate 5. Another friend of mine was even programming in the car, using a remote desktop connection to his home PC.
If your car PC is configured to connect via WiFi, and your laptop has a 3G card, you can get your car PC online using your laptop. Conversely, if you have passengers who need to get their laptops online while they ride in your car, and your car PC has a 3G card, why not make your whole car a WiFi hotspot?
Since I got my new PowerBook with built-in Bluetooth, I've used it frequently to give my WiFi-equipped CarBot an Internet connection. Since my PowerBook is already paired with my Nokia 6620, I just click "Connect" in Internet Connect on my PowerBook, which rapidly brings up a Net connection via AT&T/Cingular's EDGE network and then, using Connection Sharing (System Preferences → Sharing → Internet), shares it as a WiFi hotspot. My CarBot and any passengers with laptops (including passengers in other cars in the same vicinity!) then get the benefit of my WiFi connection.
I mention my Macintosh because that's what I use, and I find it very simple. However, there is similar software available for PCs that turns them into real WiFi access points. PCTEL (http://pctel.com/softap.php) makes a software access point product for around $20 that can be installed on a car PC with a PCI WiFi card (their site lists supported cards).
If you have a permanent 3G wireless connection set to auto-dial on your car PC, you can use the PCTEL SoftAP to make your car PC into an access point. If you happen to be in, say, a restaurant near your car and you need to get online, you can just turn on your car PC remotely [Hack #46] and then connect to the Internet through your car PC access point.