Maintaining calls while moving through the warehouse

Discussion in '3CX Phone System - General' started by way, Aug 24, 2012.

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  1. way

    way

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    I currently have several AP's scattered throughout a large warehouse which completely floods the area with a wireless signal. Although I can't give you the exact signal strength, I can say that the signal never drops below 3 out of 4 bars on my mobile.

    My problem currently exists when I am currently on a call with someone either using 3cx for android or 3cx phone for windows. Call quality will be great during the start of the call, but will have call quality issues when moving around the building. It will get to the point where the call has no audio whatsoever for a short while, but then the call resumes a second or two later with no call quality problems.

    I am thinking that this is an issue with the wireless device 'holding' onto one AP until the point where the two devices cannot communicate then quickly connects with another. Is there a way of moving from one AP to another without having to completely lose a connection first?
     
  2. lneblett

    lneblett Well-Known Member

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    In most cases wi-fi has not been very successful in the application you have and for the very reasons you mention. Network design with the AP must ensure adequate and overlapping coverage and the design of the handsets must allow for locking onto and maintaining a connection with an AP even in fringe areas where 2 or more APs may have similar coverage. This is where it usually gets sticky as the free-air coverage may appear to be the same, but the cell phone antenna design and where it is in relation to your body (as it moves around) may cause one AP to have a stronger signal than the other, but constantly changing as you move so the radio is constantly faced with which AP to use. It takes time for the handset to identify the most suitable AP and then negotiate the connection. A seemless hand-off is difficult indeed. Most cell phone wi-fi radios are not optimized for this type of service (moving between access points seemlessly for voice), largely because the processor and firmware are more geared for the cell and smartphone application speed and efficiency, which still have to be maintained even while wi-fi is in use. There are some wi-fi phones specifically made for the SIP phone market, but these too have not received rave reviews by any means, but for the most part, better than cell phones when used in a multi-AP roaming environment as their firmware and processor are most focused to the needs - no apps and cell to worry about. The other downside to the wi-fi application is the amount of power that is required, which really eats into battery life.

    Most folks have recommended going DECT for wireless as a better solution as the range is better, battery life is better and while I do not have specific experience with it, there are some systems now that support roaming. I know DECT is not the answer you wanted, but the bottom line is that you using wi-fi is somewhat of a crap-shoot as the cell manufacturers release very little info about the wi-fi radio specifications which therefore make a statement like find the cell phone with your carrier that has the fastest or most powerful processor possible along with a cell radio with the most output power across all bands and whose receive sensitivity is the best and has the ability of being able to set sensitivity threshholds so as to set the optimum value for your specific roaming application.

    Others may be able to make some suggestions, but keep in mind that a lot still rests on how your wi-fi is set.
     
  3. leejor

    leejor Well-Known Member

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    WiFi "handoff" requires a smart network, to be able to accomplish this. the device also has to have the ability to communicate with the network, to tell it, it is moving from another access point to another.

    While there are systems that will do this, they are very expensive. Mobile phones are able to accomplish this because they are specifically designed (follow standards) to work with the network, when moving from tower to tower, and not drop a call.
     
  4. RichardCrabb1

    RichardCrabb1 New Member

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    Hi,
    I just wanted to back up what Leejor had to say. We have been testing various DECT phones. It is possible for them to roam, unlike wi-fi phones where their ability is limited at best. Proper DECT solutions can be quite expensive, but RTX phones come at a good price and have roaming capability. Another one is the new Siemens 720 which also offers seamless roaming.

    Kind regards
    Richard
     
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  5. Cynthia Slade

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    You would need a smart network of AP and probably also have to give the phone a static IP so it could roam freely. Not really possible.
     
  6. RichardCrabb1

    RichardCrabb1 New Member

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    Another thought. There is now a wireless standard 802.11r. The r is for roaming. I don't know of any wi fi phones hard or soft that support this standard. Cisco does with its latest access points. Roaming switch over should take less than 50ms.

    Richard
     
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