In terms of making these cells smaller, would these be public cells, or would people start carrying around their own mini cell towers with them?
Small cell towers known as picocells and microcells are public. They're part of the architecture laid out by the cellular operators. Femtocells are desktop cell phone towers that a company or an individual would buy this for better cell phone coverage in their office or home [they can enhance a signal within a radius of 10 to 200 meters around the device].
In the case of an emergency like the earthquake or hurricane, would you have been more likely to get a signal if you had your own femtocell?
There are a number of challenges with femtocells. Earlier femtocells didn't manage their interference with one another well and weren't able to hand off to the larger cell towers outdoors. So a femtocell might have helped if you made a call indoors and stayed indoors. The question is how to do dynamic optimization of all the picocells, microcells and femtocells so that you're adapting not just to traffic changes under normal conditions but in particular under emergency situations. If an earthquake or the 9/11 attacks take out a number of towers the way the cell phone towers are configured now, service providers have to manually reroute cellular traffic; they can't adapt to dynamic changes in traffic.
The ability to do this dynamically is referred to as self-organized networks, or SONs. Combining that capability with small cells has tremendous potential to increase both the capacity and the ability to adapt to changes that are unpredictable.
How would self-organized networks, or SONs, be implemented into a cellular network?
It's a software network management tool for base stations. It can sit in the cloud, or it can sit on the mobile gateway that's managing all of the cell phone base stations.
What are some other options for improving wireless network performance?
Obviously, if capacity is a problem, throwing more spectrum at it is a way to increase capacity. Given that there just isn't a lot of spectrum available, another option is cognitive radio, which can take spectrum that's already occupied and use it more intelligently. In this way users sharing the spectrum, as they do with Wi-Fi, don't interfere with the licensed users of the spectrum, such as broadcasters. You would have to have a cell phone equipped with cognitive radio software that can find spectrum holes. For example, if you're trying to make a mobile phone call and can't get a signal, your phone would switch into cognitive radio mode and scan not just the cell phone bands but other bands for some piece of spectrum it could use.
That's a promising technology, but I'm skeptical that in the near term it will solve the capacity problem or even be viable politically. Spectrum is so precious to broadcasters and other spectrum bandwidth owners that they don't trust that secondary users can share their space without interfering.
Certainly, this distrust has been a big part of the controversy over the use of so-called white spaces between licensed bandwidth by wireless gadgets. What impact will the expansion of 4G networks have on these emergency bottlenecks that we currently experience?
Newer, 4G networks are optimized for data in the sense that they use the same network that the Internet is using. Telephone operators might just leave voice traffic on their 3G networks, which are still fairly new and not going away anytime soon. Voice requires a lot less bandwidth than data, which would then be pushed to 4G networks. In that case, things will be better in an earthquake because when you walk outside and try to make a phone call you won't be competing with people using their smartphones to send data across the same network.
Subscription Center
See what we're tweeting about
11 Comments
Add CommentRealistically, how are these technologies more likely to be used: to make cell coverage more robust in a usage spike, or to allow providers to offer just-adequate service at reduced cost?
Reply | Report Abuse | Link to thisYou know, it's funny, when I was a kid, all we had were phones that were hardwired into the wall, and barring a car hitting a pole down the road, we had dialtone - ESPECIALLY in an emergency. Maybe the old folks weren't so far off the mark - "Let's hear it for progress."
Reply | Report Abuse | Link to thisthe land line can overloaded also if too many people call at once try calling oversea at chrisimas time
Reply | Report Abuse | Link to thisAn idea that popped up years ago still has great promise for emergency communication: in the absence (or overloading) of working cell sites, phones could "fall back" to a self-organizing mesh network for text-only messaging. Messages could pass from phone to phone (silently and securely) and eventually reach their target, even if the network of cell towers was down.
Reply | Report Abuse | Link to thisThere will be technical barriers doing this: cell phones can't have enough power for a mesh network. But it is not insurmountable. This is an interesting idea. I wonder why it didn't take off.
Reply | Report Abuse | Link to thisIt has been awhile since I have left the technical field but the sentence saying data requires more bandwidth than voice is interesting. Since a data stream is a constant value and one bandwidth, I thought a voice bandwidth would require a wider, varying bandwidth? Am I wrong?
Reply | Report Abuse | Link to thisA key question: In a site designed for 100 users, what happens when the 101th user signs on? Will the system collapse, or will it service the 101th, 102th... albeit at a lower performance? Experts call the latter option "Graceful degradation".
Reply | Report Abuse | Link to thisCommercial mobile systems now mostly use TDMA or CDMA technologies; it is well known that Frequency Hopping Multiple Access (FHMA) can adapt about three times more users for the same spectrum allocation, and offers graceful degradation. Until now, FHMA was not used in cellular because of technical limitations of a small, little known, but essential component: the Phase Lock Loop (PLL). Every mobile phone has several PLLs; base stations have a multitude.
Until now, PLLs used the same basic architecture devised more than 60 years ago, which uses just a small part of the information available in the PLL - the unibit PLL. A new technology, the multibit PLL, makes use of more info in the PLL to dramatically improve performance: fast settling time, low phase noise.
The new PLL can improve wireless three ways:
* Increase the cell size, due to lower phase noise. Most of the users are located at the periphery of cells, so just a small increase in cell size can service more users, reducing No Service areas.
* Improve the effective bandwidth of each channel
* Allow the implementation of FHMA at reasonable costs.
All the above can be implemented as an improvement to existing infrastructure; new and old PLLs can coexist as the Phone Networks are gradually upgraded.
Eng. Marc Zuta.
marc@patent4u.co.il
Having been born in the ENIAC era, this is not my best subject so I have a question. Can some bandwidth be dedicated to 9-1-1 calls only. Or do they go through no matter what already?
Reply | Report Abuse | Link to thisIn 1970 it took my wife 4-hours to get through to her mother in Texas during Hurricane Celia. We were living in Monterey, CA. During her attempts to call we had a 5.4 earthquake.
Reply | Report Abuse | Link to thisLandlines are not that secure either. Usually the phone lines go down with the power lines.
In Israel, where there have been frequent terrorist attacks, we know that cell phone networks reduce or cancel service at the time of an attack (or other widespread emergency).
Reply | Report Abuse | Link to thisThe downside is that people in the area of the event cannot communicate with loved ones; the upside is that the emergency services can make use of the the networks. The periods are short but before the system was implemented the types of problems described in the article were widespread.
First on all the cell phone industry is just there to make money, period. Cheaply made equipment and minimal infrastructure. Most of what you hear about it is hype. During 9/11 only about one out of every eight cells phones across the river in NJ got service. The system couldn't take the load. Their immediate response to complaints? "It was because the towers went down." (What?) The system hasn't been improved much since it still hasn't kept pace with the number of users being added on every year.
Reply | Report Abuse | Link to thisHaving 911 calls assigned higher priority over regular calls is a good idea but that can be overloaded/misused too. How do you explain to someone looking for a relative that they are getting kicked off because an emergency call must go through?
Part of the article was amusing because it talked about smaller "cells". This was one of the first concepts of cell phones, each cell covering about four city blocks with a central microwatt transmitter with overlap of surrounding cells. Never happened probably because it was too expensive (less profit).
Most importantly, there was one major factor that the article didn't address; the user. One of the most reliable communication forms during wide area disasters is, you'll probably never guess, old fashioned ham radio. These people are trained to use the radio, many even volunteer with their own time and equipment (including generators) to pass emergency messages between government and private agencies during a disaster. These messages are prioritized into emergency (which come first), logistics and then "health and welfare". If an emergency "network" gets on a frequency, others will move off or just shut down. Can you see the average cell phone user doing this? You can't even get some to turn them off in theaters, much less not use them during a movie (or driving). How much bandwidth and backup battery power was used up by chit-chat during the hurricane? Educating the cell phone user is the easiest and cheapest fix to the problem. BTW, the whole cell concept was actually invented by a group of ham radio operators trying to improve their repeater coverage in Chicago.
I would not rely on my cell phone in a wide area disaster except as a "nightlight" so I could see in the dark. Anything else, depends....