Windows XP ad-hoc wireless sync and internet sharing (a few BT Q&A too)

Update July 2005:
It was 2002 when I first wrote this guide. Back then adhoc connection was, as I mentioned in the guide, the cheapest way to go wireless. Fast forward to 2005 - access point or wireless router prices are a fraction of what they used to be. Indeed, for the same amount of money that I paid back then for a single adapter, I can get at least a wireless router and a couple of adapters today. Add to the fact that adhoc connection can be hard to troubleshoot when it doesn't work, it is advisable to get a router or an access point and use infrastructure mode instead.

I thought I'd write some kind of guide on how I set up my system for syncing and internet access. Your system is probably different because of different network cards and drivers. Nevertheless, I hope you find something useful here. Comments, corrections, etc. welcomed.

1. Equipments

1. Desktop
   
   • Windows XP Professional (SP1 not applied)
   • Samsung MagicLan SWL-2100U USB WLAN Adapter
   • Internet access using a wired LAN card connected to cable modem
   
   
2. PocketPC
   
   • iPAQ H3630 with Pocket PC 2002
   • BUFFALO WLI-CF-S11G CF WLAN Adapter

As indicated in the title, I want to sync with my desktop and also share Internet access from there. The network consists of just two WLAN adapters working in ad-hoc mode because this is the cheapest way to go wireless. I use the built-in Internet Connection Sharing (ICS) in Windows XP.

2. Desktop

1. Set the USB adapter properties first of all:
   
   Authentication Type: Shared Key
   ESSID: (Something)
   Network Mode: 802.11 Ad-hoc
   WEP: 128-bit
   
   
   
   You may want to disable WEP when setting up the network for the first time.
   
   
2. Then the Wireless Network Connection Properties. Under the Wireless Networks tab, add a new network. Fill in the details - SSID, WEP key and check the last box to indicate this is an ad-hoc network.
   
   
   
   
3. Next, activate internet sharing. In the properties dialog for the Local Area Connection (the connection the desktop uses to access internet), under the Advanced tab, there is an option which activates ICS.
   
   

A few things to know about Windows XP ICS. Once activated, the wireless adapter will be set to a static IP address of 192.168.0.1; other clients (Pocket PC in this case) will be given an IP address by the DHCP server on the desktop.

On my system, not long after boot-up, the Wireless Network Connection will say "Connected to:" even though there's no other clients or access points around. In this state it is very easy for other clients to actually establish a connection and get an IP address. Therefore I always wait until my desktop say "Connected to:" before I try to connect from the Pocket PC.

The above behaviour might be a peculiarity of this driver and as I say, your system is probably different. (Indeed, an updated driver for the adapter seems to make this behaviour go away.) Also, I think the dialog box to add new wireless network is a little different on system with SP1.

3. Pocket PC

1. IP Address and Name Server. Located in Settings, Connections tab and Network Adapters. There is no need to set the IP address and name server, because by default it will get the IP address from a DHCP server. This dialog box also pops up when the CF card is inserted for the first time in the Pocket PC.
   
   
   
   
2. Configure the wireless network setting. This is usually provided in the driver for the wireless card. Mine is installed in the Settings|System page. Some important parameters are Mode, SSID, Channel, and of course WEP.
   A strange thing with my USB adapter driver is that there is no setting for which channel to use. So for my CF card I leave it at the default value.
   
   
   
   
3. Connection settings. All 3 fields are set to Work. Tap on Modify and check the option that says "This network connects to the Internet".
   
   
   
   
4. Host entry in registry. I used to have problem syncing wirelessly with ICS turned on - the Pocket PC would only connect as Guest. Disabling the adapter with Internet access solves the problem, but it's just too cumbersome to keep on enabling/disabling. Turns out the host name and its IP address must be entered into the registry. This is the Pocket PC equivalent of creating HOSTS file on desktop.
   Create a new key under \HKEY_LOCAL_MACHINE\Comm\Tcpip\Hosts with the name of your desktop. This can be found in System Properties, under Computer Name tab and the item "Full computer name:". Then go into the new key just created, create a new binary value named "ipaddr" (without the quotes!) with the data "C0 A8 00 01" (again without the quotes and watch the space between numbers!). The data is the IP address in Hex representation.
   
   
   
   Another easier way to do it would be to get Pocket Hosts from Marc Zimmerman. By the way, if you need a registry editor, here's one from Philippe Majerus.

That should be all for the configuration. Remember that you have to create partnership with the desktop via wired method before you can sync wirelessly.

4. Miscellaneous Questions

Q: Can I access shared folders on network?
A: Yes, Pocket PC 2002 devices can access shared folder on desktop. There is no provision for enabling shared folder on the device, though. NetRunner is one of the programs that can help you to enable the Network folder and do the mapping/unmapping of shared folder easily.
This brings us to the next related questions...

Q: Can Bluetooth do the same? Should I buy Bluetooth adapter or 802.11b adapter?
A: Syncing and Internet sharing is of course possible. Internet sharing is done differently from 802.11b. But I do not know whether it is possible to access shared folders on desktop.
As to the question of choosing Bluetooth or 802.11b adapter, it depends on the usage of the device, in my opinion. For syncing and Internet sharing, Bluetooth is probably enough. But if you intend to access shared folder or do general networking, 802.11b is probably a better choice.
Range could be another consideration. 802.11b adapters usually have longer range. Some class 1 Bluetooth transmitters might match the range of 802.11b transmitters, but this is just considering the adapters, i.e. using 802.11b in ad-hoc mode. With access points, the range of the network is usually increased because access points are not designed with stringent power constraints in mind. Therefore they can afford higher power consumption in return for better range. Choosing between 802.11b or Bluetooth access point is simple - today, 802.11b access point can be had for a much lower price compared to Bluetooth access point.

Q: "Internet sharing is done differently from 802.11b." What do you mean?
A: I mean you don't have to use ICS in Windows XP. Ok, you can use it that way as well, but another way would be to use Passthrough in ActiveSync. Passthrough let a device that is docked or connected to the ActiveSync use the Internet connection of the host computer. I mentioned this point to take us to the next question...

Q: Can I use Passthrough when syncing using wireless LAN (802.11b)?
A: I've seen a number of people asking this. The answer is no. I think the logic behind this is that if you are using network sync, you should be able to directly access the Internet without going through the desktop. If you are unable to access the Internet directly, then it is the job of a wireless router or ICS to provide this function, not ActiveSync. Passthrough works with Bluetooth sync that uses virtual COM port. To ActiveSync it should look just like a wired sync.