Bluetooth PAN issue on X220T (and probably others)

[JameZ]

Interesting indeed.

Can you try paring the X220t with your phone then from there do a speed test... check and see if there is a bottleneck at 1mb then do the same with the desktop and let me know the speed

[DeagleRevolver]

JameZ,

I've tested this on an old laptop that was recently rebuilt for use as an extra "desktop"

This did not have a need for bluetooth, so I did not bother installing the drivers though the device still "worked" as a "Generic Bluetooth Radio", with the same default PAN driver...

Bluetooth Device (Personal Area Network)

Provider: Microsoft

Date: 6/21/2006

Driver Version: 6.1.7600.16385

This laptop sure enough connected at 1Mbps.

I downloaded the driver for the integrated ASUS BT-183 Bluetooth 2.0 Adapter from Asus' website

The PAN driver updated to

Bluetooth Personal Area Network
Provider: TOSHIBA
Date: 7/24/2009
Driver Version: 6.0.724.0

The desktop adapter and the integrated bluetooth adapter on the Asus seem to use the same bluetooth stack - Toshiba's.

After installing this driver, the phone connects at 3Mbps.

Maximum speed test results from dslreports.com/mspeed

X220t (1mbps): 876kbps

Asus VX2s (1mbps): 858kbps

Asus VX2s (3mbps - post driver): 1438kbps

Desktop (3mbps): 1642kbps

The diffrences are usually more dramatic - AT&T seems to be a bit underwhelming tonight.

EDIT:

Some speedtest.net maximum results...

State College, PA hosted by Getwireless.net(recommended server) -

Asus VX2s(3mbps):1.31 Mbps, 1.18 Mbps up

X220t (1Mbps): 0.72 Mbps, 0.78 Mbps up

This was tested and repeated against the same server, moments apart.

The X220t also seems to take an extra 5 seconds or so longer during each of the "connecting" portions of the tests.

Thanks,

-DeagleRevolver

[JameZ]

@DeagleRevolver,

Seems like there are some bottleneck however I am not sure if it is caused by the drivers or hardware itself.

Will raise a case to engineering to check on this.

Appreciate if you can drop me a private message on the following information needed for me to raise this case.

Name:
Mobile:
Email:
MTM:
S/N:

Bluetooth driver:
BIOS:
Power Manager:
Power Management Driver:
Power Profile:

Windows 7 / Pro / Home / Ulti:
SP1:
x86 / x64:

//JameZ

[JameZ]

@DeagleRevolver,

The team confirmed that connecting at 1mbps is an issue. The team is looking into a fix for this.

//JameZ

[JameZ]

@DeagleRevolver,

Engineering's feedback as follows.

Windows Vista/7 shows the Bluetooth link speed is 1 Mbps by the Microsoft Bluetooth Stack in the Bluetooth Ver 2.x + EDR PAN profile, however, the actual transfer rate (throughput) is more than 1 Mbps.
Microsoft recognizes this is a Windows behavior, but does not have the plan to change this behavior.

//JameZ

[DeagleRevolver]

JameZ,

I'm afraid that answer doesn't explain this behavior...

These two screenshots were taken about a minute apart - one with 3Mbps Bluetooth, the other with the integrated thinkpad bluetooth (reported as 1Mbps)

http://i.imgur.com/BOw3q.jpg

http://i.imgur.com/lf3C4.jpg

This is a repeatable test against the towerstream server, from the same originating IP, between integrated bluetooth, and external 3 Mbps bluetooth (or wifi tethering) on the x220t, against the HTC TouchPro2, from the same location, moments apart.

The only difference between the scenarios is the speed at which the tethering adapter connects 3Mbps/54Mbps and 1Mbps.

During the integrated bluetooth tests, the bluetooth connection in task manager continuously sits between 96 and 99%, which is never the case for the other two adapters.

I must've run over a hundred tests to this day, each set of tests pointing me to the same conclusion.

Don't you agree that it seems impossible that the cellular bandwidth predictably drops down into the 0.9 Mbps bracket every time i'm using integrated bluetooth, then jumps between 1.4 - 2.7 Mbps on external bluetooth(and 1.4 - ~5 Mbps on WiFi tethering)?

Does engineering know of a practical/scientific way to test bluetooth bandwidth, say between two computers? I'd be glad to try whatever is necessary to confirm my results another way.

Normally, I wouldn't mind, but I have been out of the office a lot recently, and this limitation makes web browsing and downloading files with no other internet around painfully slow on a daily basis unless I carry around an external bluetooth adapter.

Thanks,

-DeagleRevolver 

edit note -> jpg exeeded 50k, changed to links.

[JameZ]

@DeagleRevolver,

The team tried connecting both X220 and T420, tested the transfer speed.

The following was the test result.

[Summary] Bps : Byte per second
Sending data : 200 - 220 KBps = 1.60 Mbps - 1.76 Mbps
Receiving data : 210 - 230 KBps = 1.68 Mbps - 1.84 Mbps

[Detail]
Test machines : X220T and T420s

Sending data from X220T
1st time : 200-220KBps
2nd time : 200-220KBps
3rd time : 200-220KBps

Receiving data to X220T
1st time : 210-230KBps
2nd time : 210-230KBps
3rd time : 210-230KBps

---

I will pass your findings to engineering.

//JameZ

[JameZ]

@DeagleRevolver,

Engineering's transfer speed.

http://dl.dropbox.com/u/17923542/Sent01-1.jpg

comments.

A sample of screen captures in my test.
In the screen capture, 212.3 KBps (byte per sec) = 1698.4 Kbps (bit per sec) nealy equals to 1.7 Mbps in the Coping file window. 

[DeagleRevolver]

JameZ,

I believe the testing method that the engineers are using is flawed.

Your screenshot appears to have you using the bluetooth file transfer service, which is not the bluetooth service in question.

I have no doubt the hardware itself can do 3Mbps, my concern is about the PAN driver and associated PAN service that mobile tethering connects to.

Please note how the PAN utilization in the screenshot you sent over is 0% during the transfer.

Below are some screenshots which should help clarify what i'm talking about...

One is from my X220 Tablet, the other is from a friend's W510 (which has the same driver and PAN issue). These screenshots show us transferring files to each other via Bluetooth PAN (at seperate times)

http://i.imgur.com/NyVv8.jpg

http://i.imgur.com/j3Pm8.jpg

These tests show that when a PAN connection is created, the maximum theoretical bandwidth limit is just under 1 megabit - I have seen it go as high as 121KB/s (968 kbps), and the task manager sits at 99% utilization for most of this transfer.

I have tested the file transfer service over bluetooth as well, and got significantly better results - but sadly this is not the service that PAN utilizes to transfer data.

To replicate my scenario, pair the two laptops, and create a pan connection by selection "direct connection" from bluetooth devices. Screenshot below.

http://i.imgur.com/Np9tb.jpg

Then, I assigned each of the PAN adapters an IP address, turned off windows firewall for the connections, created matching user accounts on the computers, created SMB shares, and copy/pasted a file from one laptop to the other.

Please let me know what you guys find.

Thanks,

-DeagleRevolver

[JameZ · Accepted solution]

Hello DeagleRevolver,

Engineering has tested several different profile and reverted with the following results.

---

Test 1:  T420s with internal solution.
- copying the same large .exe file held around 180KB/sec.
- on the client, Task Manager Network showed a 1Mbps connection, with around 99% usage.
- on the server, Task Manager Network showed a 3Mbps connection, with around 53% usage.

Test 2:  T510 with external cirago 2.1 EDR adapter.
- copying the same large .exe file held around 181KB/sec.
- on the client, Task Manager Network showed a 3Mbps connection, with around 54% usage.
- on the server, Task Manager Network showed a 3Mbps connection, with around 53% usage. 

---

PE followed the instructions from the customer to verify the Bluetooth performance (file transfer rate).
Our file transfer rate was around 140 to 160KB/Second (1.12 to 1.28Mbps) and was over 1Mbps, that was the link speed shown by the Microsoft Bluetooth Stack.

The folloiwng was our verification procedures.
1. Paired the two laptops (X220 and T420), and create a pan connection by selection "direct connection" from Bluetooth devices.
2. Assigned each of the PAN adapters an IP address.
    Target machine, ThinkPad X220 with the Integrated Bluetooth device, Win7 Pro 64-bit
      IP Addres       : 169.254.66.67
      Sub Net Mask    : 255.255.255.0
      Default Gate Way: None

    Server (Host), ThinkPad T420 with the Integrated Bluetooth device, Win7 Pro 64-bit
      IP Addres       : 169.254.231.176
      Sub Net Mask    : 255.255.255.0
      Default Gate Way: None
3. Turned off windows firewall for the connections.
4. Created matching user accounts on the computers.
5. Created SMB shares.
6. Created the C:\Test folder and put a 200MB file in the Server (T420) and mounted it to the target (X220).
7. Copyed and pasted the file from from one laptop to the other.

In our verification, the file transfer rate showed over 1Mbps, that was beyond the customer's test result, the CPU usage rate was almost 99%, that was the same rate as the customer had. 

http://dl.dropbox.com/u/17923542/test1.jpg

http://dl.dropbox.com/u/17923542/test2.jpg

http://dl.dropbox.com/u/17923542/test3.jpg

---

Microsoft has released a KB regarding this issue as per request by engineering as well.

http://support.microsoft.com/kb/2590977

//JameZ