[Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Arpit Rai]

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Hi!
 I'm doing a project on indoor positioning using bluetooth.

I've installed Linux(Fedore Core 4) on my comp and the Bluez Protocol Stack
to get the value of the signal strength between two Bluetooth USB dongles.
I've connected two Bluetooth USB dongles to one computer(have the USB
extension cables to increase the distance between the two dongles).When I
run the command 'hcitool lq <bdaddr>' to get the value of the link quality
between the two dongles,it is always 255.Even if I increase or decrease the
distance between the two dongles,the LQ remains constant at 255.The RSSI
value changes but this change is abrupt and does not seem like a good
measure of the signal strength. Any idea as to what could be the possible
problem with the LQ and any solutions?
 The adaptors I'm using are: Billionton Version 1.2 Bluetooth USB Adaptors
(P/N: USBBT02 (UBTBR2-B)).
 Thanks
 Arpit

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Re: [Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Marcel Holtmann]

Hi Arpit,

> I've installed Linux(Fedore Core 4) on my comp and the Bluez Protocol
> Stack to get the value of the signal strength between two Bluetooth
> USB dongles. I've connected two Bluetooth USB dongles to one
> computer(have the USB extension cables to increase the distance
> between the two dongles).When I run the command 'hcitool lq <bdaddr>'
> to get the value of the link quality between the two dongles,it is
> always 255.Even if I increase or decrease the distance between the two
> dongles,the LQ remains constant at 255.The RSSI value changes but this
> change is abrupt and does not seem like a good measure of the signal
> strength. Any idea as to what could be the possible problem with the
> LQ and any solutions?

the link quality is vendor specific. Look at my pages to find out how
CSR implemented it.
 
> The adaptors I'm using are: Billionton Version 1.2 Bluetooth USB
> Adaptors (P/N: USBBT02 (UBTBR2-B)).

What does "hciconfig hci0 version" tells you?

Regards

Marcel




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Re: [Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Arpit Rai]

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Hi Marcel
 Thanks for the reply.
 [root@174-242 ~]# hciconfig hci0 version
hci0: Type: USB
BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0
HCI Ver: 1.2 (0x2) HCI Rev: 0x0 LMP Ver: 1.2 (0x2) LMP Subver: 0x309
Manufacturer: Broadcom Corporation (15)
[root@174-242 ~]# hciconfig -a
hci0: Type: USB
BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0
UP RUNNING PSCAN ISCAN
RX bytes:412 acl:0 sco:0 events:19 errors:0
TX bytes:318 acl:0 sco:0 commands:19 errors:0
Features: 0xff 0xfe 0x0d 0x38 0x08 0x08 0x00 0x00
Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
Link policy: RSWITCH HOLD SNIFF PARK
Link mode: SLAVE ACCEPT
Name: '174-242.priv19.nus.edu.sg-0'
Class: 0x120104
Service Classes: Networking
Device Class: Computer, Desktop workstation
HCI Ver: 1.2 (0x2) HCI Rev: 0x0 LMP Ver: 1.2 (0x2) LMP Subver: 0x309
Manufacturer: Broadcom Corporation (15)
 What is the HCI build version in this case?And how does this help me?
 Regards
Arpit

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Re: [Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Marcel Holtmann]

Hi Arpit,
 
> [root@174-242 ~]# hciconfig hci0 version
> hci0:   Type: USB
>        BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0
>        HCI Ver: 1.2 (0x2) HCI Rev: 0x0 LMP Ver: 1.2 (0x2) LMP Subver:
> 0x309
>        Manufacturer: Broadcom Corporation (15) 

these chips are Broadcom based. So you must ask them how they
implemented the link quality value.

Check "hciconfig hci0 features" if they support "Inquiry with RSSI".

> What is the HCI build version in this case?And how does this help me?

The build id is only valid for CSR chips. It is not fully clear how
Broadcom encodes this.

Regards

Marcel




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Re: [Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Arpit Rai]

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Hi Marcel
 these chips are Broadcom based. So you must ask them how they
implemented the link quality value.
How is the implementation vendor specific?Does it mean that some vendors
don't support Link Quality?Or does it mean that there are other ways of
getting the LQ value?
 Check "hciconfig hci0 features" if they support "Inquiry with RSSI".
[root@175-214 ~]# hciconfig hci0 features
hci0: Type: USB
BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0
Features: 0xff 0xfe 0x0d 0x38 0x08 0x08 0x00 0x00
<3-slot packets> <5-slot packets> <encryption> <slot offset>
<timing accuracy> <role switch> <hold mode> <sniff mode>
<RSSI> <channel quality> <SCO link> <HV2 packets>
<HV3 packets> <u-law log> <A-law log> <CVSD> <power control>
<transparent SCO> <enhanced iscan> <interlaced iscan>
<interlaced pscan> <AFH cap. slave> <AFH cap. master>
 Well looks like it does support RSSI...but RSSI values change abruptly..for
the same distance the RSSI might be -9 and the after ten seconds its -2 so I
can't use RSSI.
 Do you suggest I try the LQ value with some other bluetooth adaptors?Any
idea as to which model would support the link quality feature?
 Regards
Arpit

 On 10/25/05, Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Arpit,
>
> > [root@174-242 ~]# hciconfig hci0 version
> > hci0: Type: USB
> > BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0
> > HCI Ver: 1.2 (0x2) HCI Rev: 0x0 LMP Ver: 1.2 (0x2) LMP Subver:
> > 0x309
> > Manufacturer: Broadcom Corporation (15)
>
> these chips are Broadcom based. So you must ask them how they
> implemented the link quality value.
>
> Check "hciconfig hci0 features" if they support "Inquiry with RSSI".
>
> > What is the HCI build version in this case?And how does this help me?
>
> The build id is only valid for CSR chips. It is not fully clear how
> Broadcom encodes this.
>
> Regards
>
> Marcel
>
>
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by the JBoss Inc.
> Get Certified Today * Register for a JBoss Training Course
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Re: [Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Marcel Holtmann]

Hi Arpit,

> these chips are Broadcom based. So you must ask them how they
> implemented the link quality value.
> 
> How is the implementation vendor specific?Does it mean that some
> vendors don't support Link Quality?Or does it mean that there are
> other ways of getting the LQ value?

the link quality value is vendor specific. Every manufacturer can
implement it as they like. Read the specification for details.
 
> Check "hciconfig hci0 features" if they support "Inquiry with RSSI".
> [root@175-214 ~]# hciconfig hci0 features
> hci0:   Type: USB
>         BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0 
>         Features: 0xff 0xfe 0x0d 0x38 0x08 0x08 0x00 0x00
>                 <3-slot packets> <5-slot packets> <encryption> <slot
> offset>
>                 <timing accuracy> <role switch> <hold mode> <sniff
> mode> 
>                 <RSSI> <channel quality> <SCO link> <HV2 packets>
>                 <HV3 packets> <u-law log> <A-law log> <CVSD> <power
> control>
>                 <transparent SCO> <enhanced iscan> <interlaced iscan> 
>                 <interlaced pscan> <AFH cap. slave> <AFH cap. master>
>  
> Well looks like it does support RSSI...but RSSI values change
> abruptly..for the same distance the RSSI might be -9 and the after ten
> seconds its -2 so I can't use RSSI.

But they don't support "Inquiry with RSSI" which might be more usable.
However ask Broadcom why this is so?

> Do you suggest I try the LQ value with some other bluetooth
> adaptors?Any idea as to which model would support the link quality
> feature?

The link quality is supported by every Bluetooth chip, but what this
value means is up to the manufacturer. Read the specification to
understand what this means.

Get yourself two CSR based dongles and try again.

Regards

Marcel




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Re: [Bluez-users] Link Quality between 2 Bluetooth USB Dongles

[Albert Huang]

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You may want to think twice about embarking on this project. A number of
researchers have tried this before without much success. See here, for
example:

http://anil.recoil.org/papers/2005-ubicomp-bluetooth.pdf

A Study of Bluetooth Propagation Using
Accurate Indoor Location Mapping

Abstract. The ubiquitous computing community has widely researched
the use of 802.11 for the purpose of location inference. Meanwhile,
Bluetooth
is increasingly widely deployed due to its low power consumption
and cost. This paper describes a study of Bluetooth radio propagation
using an accurate indoor location system to conduct fine-grained signal
strength surveys. We discuss practical problems and requirements encountered
setting up the infrastructure using the ultrasonic Active Bat
indoor location system, and limitations of the commodity Bluetooth devices
used.We conclude that Bluetooth is poorly suited to the purpose of
fine-grained, low latency location inference due to specification and
hardware
limitations, and note that the movement speed of mobile devices is
an important factor in calculating available bandwidth. We publish our
data sets of signal strength samples for the community to freely use in
future research.

Good luck to you if you still persist.

-albert

On 10/25/05, Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Arpit,
>
> > these chips are Broadcom based. So you must ask them how they
> > implemented the link quality value.
> >
> > How is the implementation vendor specific?Does it mean that some
> > vendors don't support Link Quality?Or does it mean that there are
> > other ways of getting the LQ value?
>
> the link quality value is vendor specific. Every manufacturer can
> implement it as they like. Read the specification for details.
>
> > Check "hciconfig hci0 features" if they support "Inquiry with RSSI".
> > [root@175-214 ~]# hciconfig hci0 features
> > hci0: Type: USB
> > BD Address: 00:10:60:B3:2C:F7 ACL MTU: 377:10 SCO MTU: 16:0
> > Features: 0xff 0xfe 0x0d 0x38 0x08 0x08 0x00 0x00
> > <3-slot packets> <5-slot packets> <encryption> <slot
> > offset>
> > <timing accuracy> <role switch> <hold mode> <sniff
> > mode>
> > <RSSI> <channel quality> <SCO link> <HV2 packets>
> > <HV3 packets> <u-law log> <A-law log> <CVSD> <power
> > control>
> > <transparent SCO> <enhanced iscan> <interlaced iscan>
> > <interlaced pscan> <AFH cap. slave> <AFH cap. master>
> >
> > Well looks like it does support RSSI...but RSSI values change
> > abruptly..for the same distance the RSSI might be -9 and the after ten
> > seconds its -2 so I can't use RSSI.
>
> But they don't support "Inquiry with RSSI" which might be more usable.
> However ask Broadcom why this is so?
>
> > Do you suggest I try the LQ value with some other bluetooth
> > adaptors?Any idea as to which model would support the link quality
> > feature?
>
> The link quality is supported by every Bluetooth chip, but what this
> value means is up to the manufacturer. Read the specification to
> understand what this means.
>
> Get yourself two CSR based dongles and try again.
>
> Regards
>
> Marcel
>
>
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by the JBoss Inc.
> Get Certified Today * Register for a JBoss Training Course
> Free Certification Exam for All Training Attendees Through End of 2005
> Visit http://www.jboss.com/services/certification for more information
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> Bluez-users mailing list
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>

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