2007-12-28 11:32:56

by Olivier Le Pogam

[permalink] [raw]
Subject: Re: [Bluez-devel] Add 3 HCI commands / concurrent connection setup question

Hi Marcel,

> However you should read the radio and baseband part of the Bluetooth
> specification and then you will realize that AFH will not help you to
> solve any page issues you see. It simply doesn't work this way and
> Bluetooth is _not_ WiFi.

I have read the specs and unfortunately certainly missed the reason why it
won't work, since AFH makes paging restricted to the provided frequency
range (not inquiry, but paging). However if you think trying this out is a
waste of time and won't help, I will follow you.

> We try with the next connection attempt once the radio is free again.
> And this is if no inquiry and no page attempt is running.

All of this is perfectly clear, however, there is something I don't get
here. Why in the case I try to setup 4 connections from 4 different devices
I still get delays (or page timeouts), as they all have their own radio. If
it's not a radio issue, I thought about interferences (so wondering about
AFH use). I suppose locks in the stack are anyway "per device".

You'll find hcidumps of 4 connection setup from 4 different dongles below.

Best regards,
Oli

-----------
HCI sniffer - Bluetooth packet analyzer ver 1.40
device: hci0 snap_len: 1028 filter: 0xffffffff
2007-12-21 15:11:41.662180 < HCI Command: Create Connection (0x01|0x0005)
plen 13
bdaddr 00:19:2D:15:FF:0E ptype 0xcc18 rswitch 0x00 clkoffset 0x0000
Packet type: DM1 DM3 DM5 DH1 DH3 DH5
2007-12-21 15:11:41.665286 > HCI Event: Command Status (0x0f) plen 4
Create Connection (0x01|0x0005) status 0x00 ncmd 1
2007-12-21 15:11:41.758270 > HCI Event: Connect Complete (0x03) plen 11
status 0x00 handle 1 bdaddr 00:19:2D:15:FF:0E type ACL encrypt 0x00
...
-----------
HCI sniffer - Bluetooth packet analyzer ver 1.40
device: hci1 snap_len: 1028 filter: 0xffffffff
2007-12-21 15:11:41.663603 < HCI Command: Create Connection (0x01|0x0005)
plen 13
bdaddr 00:17:B0:1E:54:FD ptype 0xcc18 rswitch 0x00 clkoffset 0x0000
Packet type: DM1 DM3 DM5 DH1 DH3 DH5
2007-12-21 15:11:41.666283 > HCI Event: Command Status (0x0f) plen 4
Create Connection (0x01|0x0005) status 0x00 ncmd 1
2007-12-21 15:11:42.779225 > HCI Event: Connect Complete (0x03) plen 11
status 0x00 handle 1 bdaddr 00:17:B0:1E:54:FD type ACL encrypt 0x00
...
-----------
HCI sniffer - Bluetooth packet analyzer ver 1.40
device: hci2 snap_len: 1028 filter: 0xffffffff
2007-12-21 15:11:41.664980 < HCI Command: Create Connection (0x01|0x0005)
plen 13
bdaddr 00:12:D1:65:27:7F ptype 0xcc18 rswitch 0x00 clkoffset 0x0000
Packet type: DM1 DM3 DM5 DH1 DH3 DH5
2007-12-21 15:11:41.668350 > HCI Event: Command Status (0x0f) plen 4
Create Connection (0x01|0x0005) status 0x00 ncmd 1
2007-12-21 15:12:02.148460 > HCI Event: Connect Complete (0x03) plen 11
status 0x04 handle 0 bdaddr 00:12:D1:65:27:7F type ACL encrypt 0x00
Error: Page Timeout

-----------
HCI sniffer - Bluetooth packet analyzer ver 1.40
device: hci3 snap_len: 1028 filter: 0xffffffff
2007-12-21 15:11:41.666608 < HCI Command: Create Connection (0x01|0x0005)
plen 13
bdaddr 00:12:D1:6E:4C:96 ptype 0xcc18 rswitch 0x00 clkoffset 0x0000
Packet type: DM1 DM3 DM5 DH1 DH3 DH5
2007-12-21 15:11:41.669339 > HCI Event: Command Status (0x0f) plen 4
Create Connection (0x01|0x0005) status 0x00 ncmd 1
2007-12-21 15:12:02.149466 > HCI Event: Connect Complete (0x03) plen 11
status 0x04 handle 0 bdaddr 00:12:D1:6E:4C:96 type ACL encrypt 0x00
Error: Page Timeout

-----------


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2007-12-28 19:21:01

by Marcel Holtmann

[permalink] [raw]
Subject: Re: [Bluez-devel] Add 3 HCI commands / concurrent connection setup question

Hi Olivier,

> > However you should read the radio and baseband part of the Bluetooth
> > specification and then you will realize that AFH will not help you to
> > solve any page issues you see. It simply doesn't work this way and
> > Bluetooth is _not_ WiFi.
>
> I have read the specs and unfortunately certainly missed the reason why it
> won't work, since AFH makes paging restricted to the provided frequency
> range (not inquiry, but paging). However if you think trying this out is a
> waste of time and won't help, I will follow you.
>
> > We try with the next connection attempt once the radio is free again.
> > And this is if no inquiry and no page attempt is running.
>
> All of this is perfectly clear, however, there is something I don't get
> here. Why in the case I try to setup 4 connections from 4 different devices
> I still get delays (or page timeouts), as they all have their own radio. If
> it's not a radio issue, I thought about interferences (so wondering about
> AFH use). I suppose locks in the stack are anyway "per device".

the design of AFH is to help _other_ 2.4 GHz radios to survive while
Bluetooth is active in the same area. It is not meant to protect it
against its own technology. The basics behind AFH is too play nice with
WiFi networks in the same area. That's it.

Regards

Marcel



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This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
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[email protected]
https://lists.sourceforge.net/lists/listinfo/bluez-devel