TiVo and W-Fi -- Imperfect Together - Page 2

By Joseph Moran

March 04, 2005

Mixed Signals

Once you've found and configured a compatible adapter, there are still some compromises you may have to make. Of course, if you're running a pure 802.11g WLAN, you'll need to change it to mixed mode before trying to add a TiVo to it, and this will have the unfortunate side effect of reducing the performance of all of your wireless devices. There are a couple of ways around this problem, both of which involve the purchase of additional hardware.

One method is to set up a separate 802.11b AP for the TiVo so you can keep things like PCs and game consoles running on the 802.11g network. To do this, you'll need to make sure both networks are set up on non-overlapping channels. However, depending on how many other WLANs are near you (neighbors, etc.) you may not be able to avoid interference since there are only 3 such channels available on a 2.4GHz WLAN.

Another way you can avoid having to run your 802.11g network in mixed mode is to use a USB-to-Ethernet adapter to connect your TiVo to an 802.11g Ethernet-to-Wireless bridge. (But this won't necessarily get you to 802.11g speeds, as we'll see in a moment.)

TiVo and 802.11g

So what about direct TiVo support for 802.11g hardware? As previously mentioned, Tivo has recently added the first 802.11g devices to it's compatibility list, the D-Link DWL-G120 and the tiny Netgear WG111. Despite this, there are still some major catches to be aware of.

First, you need to be using a particular version of the TiVo DVR software (specifically, version 7.1), which is currently available only on request. (You can fill out a form on TiVo's Web site and provide your unit's serial number, and the software will be downloaded to your unit within a few days.) Unfortunately, this software update isn't currently available for TiVo models with a built-in DVD recorder, (like one of my two TiVo units, a Toshiba RSX-T60) so these units must soldier on with 802.11b for now.

Finally, just like with the 802.11b adapters, there are multiple hardware versions of the D-Link and Netgear 802.11g adapters, and not all versions are supported by TiVo. Therefore, not every G120 or WG111 will be compatible.

But Wait, There's More

As if the vagaries of TiVo's labyrinthine wireless support didn't give you enough to ponder, you also need to consider the speed of the TiVo's USB ports.

According to TiVo, almost all Series 2 TiVo units have USB 2.0 ports. (The exceptions are the earliest Series 2 models, which have a Tivo Service Number beginning with 140.) That's good news, because USB 2.0 can supply 480Mbps of throughput, which is well in excess of what even the fastest WLAN is likely to be capable of today.

Here's the rub: at the moment, all TiVo system software operates the USB ports at USB 1.1 speeds —a mere 12 Mbps. Therefore, even on a wired network, your TiVo's USB ports will be a serious performance bottleneck, and it's the reason you won't realize 802.11g speeds by if you use an 802.11g adapter or combine a wired USB adapter and 802.11g wireless bridge as described earlier.

Either arrangement does have the benefit of allowing you to run your WLAN in pure-G mode, however.

Transferring Data

When a wireless network only needs to support mundane PC tasks like Web browsing, the speed usually isn't terribly important. But when you consider the size of a recorded video file can range from hundreds of megabytes to a gigabyte or more (depending on the length of the program and the quality at which it was recorded), and that you want to move these gargantuan files between DVRs or between a DVR and a PC, how fast a WLAN can transfer data becomes very important indeed.

To get a sense of how long it would take to offload programming from a TiVo over a WLAN, I networked my two Series 2 units with the aforementioned D-Link DWL-122 802.11b adapters. (Incidentally, the DWL-122 is one of very few 802.11b adapters from a major vendor that doesn't have multiple hardware versions.) Unfortunately, the performance was unimpressive to say the least. In fact, it took a bit over four hours to transfer a one-hour program recorded at "high" quality, which is the second-best level on TiVo. Programs recorded at lower quality levels (and thus with smaller file sizes) would of course take less time to transfer, and had the units been communicating over a pure 802.11b network instead of a mixed mode 802.11g one, transfer time would probably have been somewhat shorter, though likely not significantly.

In any event, it seems clear that for the moment using WLAN adapters to transfer TiVo programming— especially at higher quality levels—will require forethought and a large dose of patience. And given the current USB bottleneck, even wired adapters will likely not be able to transfer programming in anything resembling even real time.

Conclusion

In the final analysis, all of the difficulties and compromise associated with putting TiVo on a WLAN stem from the use of USB ports rather than Ethernet. In retrospect a built-in Ethernet port (as can be found in the Xbox game console) would have been a much better choice given that it introduces no performance bottlenecks and eliminates the need for drivers. One can only hope that in the future TiVo will jettison USB in favor of Ethernet.

Although you can put your TiVo on a WLAN, and you will definitely get some benefit out of doing so—most notably the remote programming and freeing your TiVo from the tyranny of a phone line—the bad news is that getting TiVo on a WLAN is much harder than it needs to be and it forces you to make significant compromises. Don't expect to be quickly zipping TiVo programs around your WLAN— at least not yet.

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