Archive for June 21st, 2010

Five Problems with Cell Phone Networks

Five Problems with Cell Phone NetworksMany people do not have any appreciation for just how complex the Cell Phone Networks are and how easily congestion can delay or prevent calls going through the network. There are many locations within the network that can act as choke points. The engineers at these communications companies are always monitoring and improving this network. However it does take time to update these networks. Frankly if a given area does not have enough potential to drive revenue, the carriers will not invest a lot of money into these poor service areas.

There are 5 main areas that these choke points can be lumped into. We will discuss them in a moment. However when you add data calls, the amount of traffic increases exponentially and places additional strain on the network. In fact data is growing at a higher rate than voice traffic. This is becoming a challenge to many cell phone companies since they need to spend millions of dollars to fix some of these data choke points to deal with the exponential growth in traffic.

The 5 areas are: A) Airwaves B) Buildings C) Switching Gear D) Land Lines E) Application Servers. A data bit travels from your cell phone via airwaves, through building walls to cell towers, then via land lines to switching , more land lines to applications servers which will process the data bits and deliver back to you the information you requested. There are ample opportunities for the data bits to be slowed or delayed while each device deals with the traffic that is being sent to it. As traffic increases this only gets worse unless additional capacity is added.

Cell Phone Networks Problems

Airwaves

Congested airwaves are less problematic than other choke points, but they still slow service.

Take the fastest 3G network today, which can support a download speed of 21 mega bits per second. Someone using a laptop wireless card that also supports 21mbps can surf the web at full speed.

But if two laptop users try to download at 21mbps from the same cell tower, the highest speed each consumer will see is cut in half. If a third user tries to download at the highest speed, divide the peak speed by three, and so on.

Fortunately not every laptop needs or can deal with 21 mbps, but you get the point when you have a congested site that has thousands of cell phones, or wireless cards competing for limited resources the response time can become delayed.

Buildings

City skyscrapers block wireless signals, and office workers using cell phones at their desks clog networks originally designed for people on the go.

These same buildings can attenuate a signal so much that a cell phone can work perfectly fine outside and not at all inside. Weaker signals slow the transmission of data  and use your batteries power much faster.

Switching Gear

Applications like Yahoo Messenger that constantly send and receive signals on the network play havoc with switches, which were built for sustained calls. A two-minute IM chat can require as many signals as it takes for 10 voice calls. A single computer with an air card can be running 4 or 5 applications at the same time, generating data traffic from each of the applications aimed at different servers in the network.

Signaling traffic is growing 50% faster than data as more apps are constantly “on,” according to Signals Research Group. That’s in part why iPhones generate more traffic than 30 basic cellphones.

Landlines

Data bits flow from cell towers through fiber and copper lines to a switching station. Then from the switching station again via land lines to application servers via even more switching stations. Data and calls are then sent to their final destinations over even more landlines and servers.

The scheme, designed pre-smartphone, can push only 75% of a tower’s maximum capacity to the next switch or endpoint. Wireless data is expected to more than double annually from 2008 to 2013. Video and apps will grow more popular, landlines are a growing problem.

Application Servers

Many of the tens of thousands of applications for smartphones connect to the public Internet through their own servers. So don’t always blame the wireless carriers for bad service. Slow loading corporate e-mail or sports scores can be the fault of an app maker’s own bandwidth constraint.

It does not matter whether it is ITunes, CNN or any other site that is receiving lots of traffic from all over the world. The application servers must receive the data, process it, and determine what information is being asked for. Once they ind it, queue it for transmission and then send it back to the original requester there are many obstacles.  And this is the simple straight forward version.

Applications servers can be their own choke point if many users are making the same request at the same time. This occurs routinely when something is advertised on a web site or on TV and thousands of people make the same request at the same time for information about the same subject.

Cell Phone Networks – Summary

With all of these possible choke points in the network it is amazing that the communications system works as well as it does. Rest assured that data engineers are monitoring and making adjustments routinely every day. They improve the network and adding capacity to deal with an ever increasing traffic demand. Especially as more and more smart phones are added by customers across the country.

For more wireless internet details and info, click here.

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Fixing Garage Door Openers

Maintenance of garage door openers and fixing Garage Door Openers are not a big issue for most people. These units are installed by a professional usually and once installed, there is not much that needs to be done with Fixing Garage Door Openersthem. Most will last from 5 to 20 years, some even longer without ever being touched, while others will need some sort of repair or adjustment from time to time.

Maintenance of Automatic Garage Door Openers

As we said there is not much to do, however when you are doing your quarterly check of your garage door ( see previous post) , it is a good idea to check a few things with respect to the automatic garage door opener as well. A simple check can add years to the system if bolts that are loose are tightened and the chain is working properly.

  • check the batteries in the remotes that you use and replace them if required.
  • check the safety stop of the garage door and adjust if needed. The safety stop  makes sure that your door will stop and re-open if it finds that there is something blocking the closing of the door. It is very important to make sure this is working, especially if there are small children around.
  • check that the door fully closes and  fully opens, adjust if required.
  • check the chain, and lubricate if needed. There are other types of mechanisms that are used besides chains. Check in your manual to confirm what kind of lubrication should be used and how often.

Check Your Garage Door Opener First

Automatic garage door openers have become quite inexpensive and as a result you probably will not be able to find anyone who will be wiling to take them apart to repair them.  Even if you can, by the time you pay to have it repaired, you will be pretty close to the cost of a new one.

There are a few basic things you should do to confirm your door opener is really not working before you decide to replace it.

  • check that the batteries for your controllers are working
  • try opening the door with other door openers, including the manual button that most people will have in their homes.
  • check that the power is on and that a circuit breaker has not tripped for some reason, preventing power getting to the garage door opener.
  • disengage the chain from the garage door and try operating the garage door opener. If it works there may be a problem with your door.

Once you have tried all of these steps, you may want to call a repairmen, however there is a big trade off here in terms of what the cost will be to replace the door opener vs repairing it. Most people will opt for replacement since they have become so inexpensive.

Repair or Replace

Of course there are always fancy multi featured door openers that can cost a great deal of money, however the inexpensive ones will cost somewhere between $100 to $200. You can barely get repairmen to show up for $100 these days and before you know it the cost of checking and repairing the system costs more than a new one.  In addition there is no guarantee that he will be able to fix it.

Our conclusion is that if you cannot fix it yourself, then you might as well put a new one in.

There is really not much to a garage door opener. Essentially there are 4 parts. The electric motor, the gear box which connects to the chain. There is a printed circuit board which controls the motor. There is another printed circuit board which receives the transmissions from the remotes. Most units will have these functions combined on one printed circuit board.

Can You Do the Repairs Yourself

If you are not handy at all then you probably will not want to attempt these suggestions in this next section. First of all disconnect the power to prevent any possibility of electrical shock. Secondly, remove the cover on the housing of the door opener. You should be able to observe the 4 components we discussed earlier.

At this point most people will only be able to observe whether there are any loose or frayed wires. They should check that the printed circuit board is properly seated in place. If you cannot see anything obvious, then you are looking at buying a new system. Repair any wires that are frayed or disconnected and then retry opening your door.

Anyone with PCB expertise will probably enjoy the challenge of testing the board. However this is way beyond what most consumers are willing to consider and are able to do.

Replacing a Garage Door Opener

There are many styles and types available. We suggest that you replace like for like if possible to make the entire job easier. There will be less adjustment of existing supports etc. You might even be able to use the same chain if it is still in good shape.

Hire a handyman if you are not comfortable with doing the installation of the automatic garage door opener yourself. This will cost you an additional fee.

Good luck with maintaining your door and saving money. Comments are welcome.


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