[PATCH] wpa_supplicant: Enable HT40 support for AP mode

Jouni Malinen j at w1.fi
Mon Jul 9 14:36:22 EDT 2012


On Mon, Jul 09, 2012 at 03:13:23PM +0530, Rajkumar Manoharan wrote:
> I thought of that too. But how about the channels that can operate in HT40+
> and HT40- like channel 6. How can we determine that on which mode AP should
> start with? So I followed the existing hostap approach.

Deciding something like this based on a global configuration parameter
does not make much sense to me. If you need to specify HT40+ vs. HT40-
(which would only be the case on some 2.4 GHz band channels), it should
really be done as part of p2p_connect/p2p_group_add command parameters
or as a network block parameter rather than global parameter.

> > > diff --git a/wpa_supplicant/p2p_supplicant.c b/wpa_supplicant/p2p_supplicant.c
> > > @@ -2231,10 +2231,8 @@ static int wpas_p2p_setup_channels(struct wpa_supplicant *wpa_s,
> > >  	struct p2p_oper_class_map op_class[] = {
> > >  		{ HOSTAPD_MODE_IEEE80211G, 81, 1, 13, 1, BW20 },
> > >  		{ HOSTAPD_MODE_IEEE80211G, 82, 14, 14, 1, BW20 },
> > > -#if 0 /* Do not enable HT40 on 2 GHz for now */
> > >  		{ HOSTAPD_MODE_IEEE80211G, 83, 1, 9, 1, BW40PLUS },
> > >  		{ HOSTAPD_MODE_IEEE80211G, 84, 5, 13, 1, BW40MINUS },
> > > -#endif
> > 
> > Why? 40 MHz channels on 2 GHz band were disabled on purpose and I would
> > like to keep this separate from the possibility of using 40 MHz channels
> > on 5 GHz.
> If so, for 2GHz band alone cards we are not supporting HT40 in P2P mode.
> Before starting in HT40 mode, we are already going though OBSS process.
> Then why do we have to disable HT40 mode?

I would like to keep this change separate from the rest of the patch to
keep these topics independent of each other. I have nothing against
enabling 40 MHz channels on 5 GHz band for P2P use cases, but I'm not
sure I would really like to see that as the default behavior for 2.4 GHz
band. And even if ever enabled for 2.4 GHz, a more robust mechanism
would be to first initiate the GO with 20 MHz channel and then switch to
40 MHz channel based on the co-existence procedure defined in 802.11n
afterwards.

-- 
Jouni Malinen                                            PGP id EFC895FA


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