May 12, 2011Prakash Sangam
The explosive growth in social media that my friend Sachin discusses in his blog, is fast becoming a reality in many parts of the world, adding to the unprecedented demand for data services. If the constant flurry of new smartphones and tablets being announced is any indication, the onslaught will continue far into the future.
Adding to the mix is the 800 pound gorilla in the room — machine to machine, which we are only starting to get the hang of. With all this expansion, one lingering question on everybody’s mind is “will the wireless networks be able to keep up with this growth?”
The obvious answer is a resounding YES. As I have explained in these blogs, 3G/4G networks are well equipped now, and evolving in the future, to address the massive increase in the sheer volume of data growth. But, being the technologists that we are, we like to go beyond simply answering the question. We seek to dig deeper, to analyze and understand all aspects of this growth, and more importantly, to invent well-rounded solutions that will enable all the stakeholders to cost-effectively address it.
As has been very well established by now, smartphones are the key drivers for this increase in data demand. When you take a close look under the hood, interesting facts emerge about smartphone usage behavior and the corresponding network resource utilization.
Unlike the connected laptop or computer, smartphones connect intermittently to the network, and generate very small amounts (mere tens of kBs) of extremely bursty traffic. For example, when you check for updates from email programs or from social media apps (e.g., Facebook, Twitter), check weather, use location based services, send presence updates for IMs… and many more activites — often described as “chatty apps.”
Every time these apps get updates, the smartphone has to establish the connection, do the data transfer and tear down the connection, which means lot of signaling. Often that means more signaling than actual data transfers. There have been many studies on this, validating the fact that smartphone-generated signaling overwhelms wireless networks. The trend of vastly popular social media going mobile will only further amplify this effect.
Thankfully, the wireless industry has already heeded the early warning system and has introduced many enhancements into the wireless evolution path to address these signaling challenges. Wireless technologies are designed with the dynamic nature of the market in mind, hence there are many levers to fine-tune the system.
For starters, optimizing many of the system parameters such as dormancy timers, access parameters, etc. are the first line of defense. The evolution track also has many enhancements built in, some of which are already being put to work in today’s networks.
HSPA+ has features such as Enhanced Cell-FACH (Forward Access Channel), and CPC (Continuous Packet Connectivity), which includes device-based DTX (Discontinuous Transmission) and DRX (Discontinuous Reception).
I know that this long list of acronyms may seem like a mouthful of technical mumbo-jumbo, but let’s dissect and explain them a bit. Every time a device wants to send or receive data, it requests resources using an overhead channel such as the “Access” channel.
The network allocates “Traffic” channels for data transfer. This process needs about 20 messages to be exchanged between the device and network, which might be okay if you are transferring large amounts of data. But it will definitely be overkill if the amount of data is small.
Enhanced Cell-FACH optimizes the system such that the access channel can be used to carry small amounts of data. This process only needs 3 messages to be exchanged, significantly reducing the overhead.
On the EV-DO side, the current design is inherently focused on brevity toward signaling overhead, and is open enough for many parameter optimizations. Tweaking the parameters such as dormancy timer, power control and access signaling setting yields considerable improvement. And additional gains can be achieved by interference cancellation. Further, DO Advanced introduces Enhanced Connection Management features that look at using overhead channels (such as paging) to increase the capacity of the system to support many smartphones using chatty apps.
DTX and DRX are simple, yet powerful device features utilized in both HSPA+ and EV-DO systems. They simply turn OFF the transmitter (for DTX) or receiver (for DRX) when there is no data to be transferred, while still maintaining the connectivity.
For example, once you have downloaded a web page, and are reading it, there are no data being transferred until you click on a link. Apart from increasing capacity, these features also significantly improve battery life for smartphones.
I know, there is a lot of technical information here, which reminds me of a cartoon I once saw with the caption, “Science, science, science… BOOM you get More! And More is Better!” Akin to that, the key takeaway here is— technology is on your side, and if you’re like me, you’ll find it reassuring to understand that you are well protected from the flurry of data headed your way.
HSPA+EV-DOLTESmartphonesTablets40May 12, 2011