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371 Posts

12-05-2009

Boston

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Re: Yoga 2 Pro Wifi Problems

2013-12-16, 2:48 AM

Some more interesting facts about HT mode..

 

A device that uses 802.11n high throughput (HT) mode -- also known as Greenfield mode -- assumes that there are no 802.11a/b/g stations using the same channel. 802.11a/b/g devices cannot communicate with a Greenfield AP. Instead, their transmissions are likely to collide, causing errors and retransmissions for both parties.

 

Normally, 802.11 devices share channels by sensing when another device is transmitting, using a back-off timer to wait until the channel is free. However, because an 802.11a/b/g device cannot tell that a Greenfield device is transmitting, it will go right ahead and transmit. To avoid this, the 802.11n standard also defines an HT mixed mode.

 

A device using HT mixed mode prepares to transmit in both the old 802.11a/b/g fashion and the new 802.11n fashion. Specifically, HT mixed mode devices transmit a legacy format preamble, followed by an HT format preamble. An HT mixed mode device must also send legacy format CTS-to-Self or RTS/CTS (Request to Send/Clear to Send) frames before transmitting. These "protection mechanisms" let nearby 802.11a/b/g devices -- including those not connected to the HT mixed AP -- sense when the channel is busy.

 

Of course, these protection mechanisms significantly reduce an 802.11n WLAN's throughput. But they are a price that must be paid to coexist peacefully with 802.11a/b/g neighbors.

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89 Posts

05-09-2009

Ohio

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Re: Yoga 2 Pro Wifi Problems

2013-12-16, 2:56 AM

Well Im not sure what all that does but my signal strength is now fantastic.. Thanks for the info on this HT mode... 

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966 Posts

01-28-2013

United States

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Re: Yoga 2 Pro Wifi Problems

2013-12-16, 4:28 AM

wrote:

Some more interesting facts about HT mode..

 

A device that uses 802.11n high throughput (HT) mode -- also known as Greenfield mode -- assumes that there are no 802.11a/b/g stations using the same channel. 802.11a/b/g devices cannot communicate with a Greenfield AP. Instead, their transmissions are likely to collide, causing errors and retransmissions for both parties.

 

Normally, 802.11 devices share channels by sensing when another device is transmitting, using a back-off timer to wait until the channel is free. However, because an 802.11a/b/g device cannot tell that a Greenfield device is transmitting, it will go right ahead and transmit. To avoid this, the 802.11n standard also defines an HT mixed mode.

 

A device using HT mixed mode prepares to transmit in both the old 802.11a/b/g fashion and the new 802.11n fashion. Specifically, HT mixed mode devices transmit a legacy format preamble, followed by an HT format preamble. An HT mixed mode device must also send legacy format CTS-to-Self or RTS/CTS (Request to Send/Clear to Send) frames before transmitting. These "protection mechanisms" let nearby 802.11a/b/g devices -- including those not connected to the HT mixed AP -- sense when the channel is busy.

 

Of course, these protection mechanisms significantly reduce an 802.11n WLAN's throughput. But they are a price that must be paid to coexist peacefully with 802.11a/b/g neighbors.


Thanks for the info. It does seem that Intel's drivers for Windows 8.1 have problems with getting their Wireless-N to be stable with neighboring a/b/g radios. Well, a well functioning 802.11n in mixed mode IMO should still be reliable and should still be able to get much faster throughput than Wireless-G specs. Like I wrote in my previous post, I used to have speed and reliability issues with 802.11n mixed mode with my 7260N and disabling HT mode is the temporary solution I had while waiting for the stable Windows 7 drivers. When 16.1.5.2 drivers for Windows 7 came, I now have stable HT mode in mixed radio mode (aka b/g/n mode in router) environment. I haven't had limited connection nor speed and connection drops with HT mode enabled and mixed mode settings in router since then. My throughput in mixed mode, 144 Mbps connection is around 7 - 9 MB/s (56 - 72 Mbps). Selecting the best channel with the help from inssider also contributed to my Wireless-N stablitliy. Sadly, Intel still hasn't completely fix this Wireless-N issue with their 16.5.3.6 drivers as well as their drivers for Centrino 2230 and 6235.

 

For those people with Y2P who don't have WiFi problems, I suspect that many of them don't have more than 20 neighboring WiFi radios in sight. As such they have less interference problems with Wireless-N and b/g radios from adjacent and overlapping channels resulting to stable and fast WiFi.

Lenovo Y470: i7-2670QM | 8 GB DDR3 1333 MHz RAM | Nvidia GeForce GT 550M | 500 GB 7200 RPM Seagate HDD | ASUS PCE-AC56 802.11ac Network Adapter | Windows 7 Professional 64-bit
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5 Posts

12-15-2013

Brazil

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  • Message 424 of 1678

Re: Yoga 2 Pro Wifi Problems

2013-12-16, 11:32 AM

Yep... I had to disable HT Mode with the new driver too.

It`s sad to have this kind of problem with a wannabe top notch product... ):

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16 Posts

11-06-2013

md

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  • Message 425 of 1678

Re: Yoga 2 Pro Wifi Problems

2013-12-16, 13:05 PM

thanks for the info on disabling HT Mode.

 

Internet seems slower, but could be my imagination.  the speed did go from 164mbs to now 54.  but so far no disconnects or limited, which is good for me.

 

hope they have a fix to get this working with HT mode someday.  Thank you again.

 

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76 Posts

10-28-2013

Lynbrook, NY

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  • Message 426 of 1678

Re: Yoga 2 Pro Wifi Problems

2013-12-17, 14:16 PM

This has nothing to do with a "wannabe top notch produce" as you state. This has everything to do with the lack of transmittable frequencies in WiFi networking. There are many, many channels that overlap everywhere on the globe..and that is a problem that technology is trying to handle (e.g. 5 Ghz band).

Many people think these problems stem from the computer itself...while some of them do, some are also not a direct problem with the computer. E.g...Disabling IPv6 does help with connections all around. This is not a "computer problem" but rather a problem with tech implementing a service which is not fully operational yet.

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7 Posts

12-09-2013

Germany

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  • Message 427 of 1678

Re: Yoga 2 Pro Wifi Problems

2013-12-17, 21:54 PM

Okay, really weird: As soon as I start a backup using Windows integrated tool it will disable the wireless service and therefore disconnect. I have no idea what's causing this. (backup would be to a Time Machine network HDD (NAS)

 

Disabling HT mode does not work, because i cannot connect to my AP then (I see the SSID but it won't connect)

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966 Posts

01-28-2013

United States

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Re: Yoga 2 Pro Wifi Problems

2013-12-18, 4:15 AM

That just means that the your Access point is only accepting Wireless-N. Disabling HT mode in your WiFi card is equivalent to disabling Wireless-N and just running Wireless-G which your access point rejects. Also try to restart the WLAN autoconfig and make sure the startup type is set automatic. Also upgrade your WiFi drivers here and see if it helps http://www.intel.com/support/wireless/wtech/proset-ws/sb/CS-034041.htm:

Lenovo Y470: i7-2670QM | 8 GB DDR3 1333 MHz RAM | Nvidia GeForce GT 550M | 500 GB 7200 RPM Seagate HDD | ASUS PCE-AC56 802.11ac Network Adapter | Windows 7 Professional 64-bit
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7 Posts

12-09-2013

Germany

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  • Message 429 of 1678

Re: Yoga 2 Pro Wifi Problems

2013-12-18, 17:48 PM

Okay, thats why HT mode is not working.

 

The other stuff does not help. Latest drivers are already installed and the service starts. It is running but immediately crashes when starting the backup.

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5 Posts

12-15-2013

Brazil

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  • Message 430 of 1678

Re: Yoga 2 Pro Wifi Problems

2013-12-18, 18:18 PM
As far as I know 802.11n has been a standard for a while and works with 2.4Ghz. Yoga doesn't support 802.11ac which is 5Ghz. You're misleading people with your comment.

If Yoga worked with 5Ghz I would kind of understand the issue. Problem is Yoga uses 802.11n. I have 2 Vaio with 802.11n and they work very well in my network. All my other devices work well, including my HT, Google TV, and Xbox One.

There is no reason to say it's not Yoga's problem.
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