With the launch of Verizon's LTE network, Metro PCS's entry into the world of LTE, and WiMAX gaining subscribers in many cities from Clearwire and Sprint, it is time to take a look at what these fourth-generation technologies are promising and what they can really deliver.
There has been a lot of hype surrounding both WiMAX and LTE when it comes to data speeds, so some potential customers may have the expectation that these technologies offer data speeds of 50 Mbps and above. The press is filled with infrastructure vendors touting their "first 50 Mbps data call" over LTE, and some within the WiMAX community are making tall claims as well.
Both LTE and WiMAX, unlike their second and third-generation predecessors, were conceived and designed from the ground up for broadband data service. This does not mean voice over IP (VoIP) does not work over these networks; it means that both LTE and WiMAX have been optimized for broadband data services and offer low latency (important for encryption and fast access). VoIP is treated as simply another form of data with one exception: VoIP will require quality of service (QoS) and priority over data services since voice packets are time-sensitive.
For the next few years, customers must face the reality that LTE and WiMAX systems are not ubiquitous, thus customers who travel or are truly mobile will be switching between 3G and 4G networks. This means applications should be developed to work well over 3G networks and work better and faster over 4G networks. Building apps that rely on data speeds available only on 4G systems will result in users being disappointed with the applications' performance when they are in 3G coverage. I have delivered this message to the developer community on numerous occasions, but it bears repeating here for those who roll their own applications.
What real-world data speeds can we expect from 4G systems? According to the Clear Web site, Clear and the Sprint 4G WiMAX network speeds are up to 6.0 Mbps for the downlink and up to 1.0 Mbps for the uplink. While Verizon's network is still new, the published expected speeds of its LTE network are from 5 to 12 Mbps for the downlink and from 2 to 5 Mbps on the upload side (to the network). These numbers reflect average speeds users can expect on the networks. There will be times when data speeds are faster and times when they are slower.
Data speeds for both WiMAX and LTE are limited by the amount of spectrum in which a network operator has to deploy the technology. Clearwire is using 30 MHz of spectrum per market and Verizon's LTE network is based on 20 MHz of spectrum (10 MHz by 10 MHz). Data speeds will also vary based on the number of users within the same cell sector and the type of data they are using. A typical cell site has three 120-degree sectors radiating out from the cell site, and each of these sectors is capable of providing the full system bandwidth
If you are the only customer in a given sector, all of the bandwidth and data speed is yours. However, if you are in a sector with a number of other network users, the bandwidth is shared. You cannot simply say that if there are ten users within a cell sector you only get one-tenth of the bandwidth. The amount you have depends on another set of variables including your distance from the center of the cell site. The closer you are, the faster the connection, since data speeds fall off quickly at the edge of a cell.
The next consideration is the type of data being used by the various users. If they are all surfing the Internet, e-mailing, and performing other fairly light data tasks, data speeds will appear to be near the norm for all users. However, if a few are streaming video to their notebooks or sending videos to others, the data speed will be lower for everyone else in the cell sector.
One advantage of the LTE technology is that it adds what is known as quality of service or QoS, which can be used to assign certain levels of priorities to users. Along with other hooks built into LTE, QoS can be used to throttle data hogs down in speed so more capacity is available for other customers. (The above types of sharing and their effects on data speeds are also manifested in 2G+ and 3G networks.
I would be remiss if I did not mention that there is a 3G technology capable of higher data rates, and it has been deployed by T-Mobile USA in many cities. It is called HSPA+, and according to recent press releases, downlink speeds can be as high as 7+ Mbps, and the 3G+ network is touted as having 4G data speeds.
The bottom line for corporations is that if their applications are running well over today's 3G wireless broadband networks, they will perform even better on the 4G networks. However, if you develop applications that rely on 4G data speeds, for the next three or four years, your users will be disappointed in their performance when they are in 3G-only markets. LTE and WiMAX (and HSPA+) are all great improvements over today's 3G networks, but they won't boost your data rates from 1 Mbps to 50 Mbps. Most likely, users will experience twice the speed and performance when on a 4G network over what they are accustomed to on today's 3G networks.
Andrew M. Seybold is CEO & Principal Analyst with Andrew Seybold, Inc., a wireless industry consulting and research firm. Visit www.andrewseybold.com for more information.