On Sunday 31 May 2009 11:15:58 am Tomeu Vizoso wrote: > On Sun, May 31, 2009 at 16:09, Tiago Marques <[email protected]> wrote: > > On 5/31/09, John Watlington <[email protected]> wrote: > >> On May 30, 2009, at 12:04 PM, Reinder E.N. de Haan wrote: > >>> Subject: Xo 1.5 wlan > >>> Date: Thu, 07 May 2009 19:56:27 +0200 > >>> From: Reinder de Haan <[email protected]> > >>> To: John Watlington <[email protected]> > >>> > >>> Hello, > >>> > >>> I have a couple of questions regarding the wlan module in xo 1.5; > >>> > >>> 1) will it be an off the shelf module (3th party) or a quanta/olpc > >>> 'private' module > >> > >> One of the complications of the Gen 1.5 design has been improving > >> the WLAN module. The existing module takes lots of power, and > >> the USB driver still needs extensive modification to speed up > >> suspend/resume. > > > > Being power the major concern, will wireless range also be enhanced in > > some way? Most of the early claims that the XO had a top class > > wireless range have not materialized, at least when I compare it to > > other devices like a Fon2100 or an IPW2200 from Intel, which is > > probably the device with best wireless range that I've ever seen. > > > > A way to change the transmit power in software would be great for > > power and range, depending on the application. Does the module have > > anything like that or are you just mainly focusing on power and > > relegating range to 2nd place? > > I think that there have been recent improvements in the algorithm for > choosing the transmission power in the linux kernel. I'm not sure if > all wifi drivers benefit from it, but a laptop with b43 has improved > dramatically its range after updating to Ubuntu Jaunty.
I think what you're talking about is the rate selection algorithm, I dont think the kernel dynamically changes the Tx power. Linux has moved to minstrel [0] as its default rate control algorithm, which is way better than what we had previously in dealing with lots of collisions, where slower rates may not increase the chance of getting a packet through. This scenario is common in schools with lots of XOs. Some drivers still have their own algorithm, it is probable that the closed fullmac Marvell implementation has one. [0] http://linuxwireless.org/en/developers/Documentation/mac80211/RateControl/minstrel > > > Best regards, > > > > Tiago Marques > > > >> Unlike Gen 1, we don't have the time or expected market to > >> develop and certify a custom module. > >> > >> The current plan is to use an existing WLAN module, based on > >> the Marvell 88W8686 and connected to the system using an > >> SDIO interface. > >> > >>> 2) if it is a private module please break out jtag and the serial port > >>> for debugging (xo 1.0 only had jtag.. serial ended right at the > >>> balls of > >>> the chip :-( > >> > >> Sorry, the module doesn't bring any of the internal debugging signal > >> out. > >> > >>> 3a) if its a 3th party moduel is it posible to buy it somewhere ? > >> > >> Yes and no. There are 88W8686-based SDIO modules already > >> available, and electrically/software-wise they will be identical to the > >> one we are planning to use. > >> > >> The actual module used in XO-1.5 will have a half-height miniPCI-e > >> form factor. Even if you could buy it in small quantities, you > >> would have > >> to arrange an adapter board to use internally. > >> > >> Cheers, > >> wad _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
