IMS and WiMAX (February 5, 2008)

It is clear that despite all the delays in the standartization and implementation procedures IMS will be starting its deployment sooner or later — probably as a service layer of 3GPP Long Term Evolution. This set of specifications, apart from the fact that it is purely IP-based, is especially interesting because it does not limit the way how terminal equipment should access the base station and, after all, the core network.

Among the air interfaces (or access modes), WiMAX looks better than others (actually, there’s a “battle” between LTE and WiMAX which I found overhyped, and therefore will write about this some other day). It is defined as a set of IEEE standards (802.16), and there are some chipset implementations of it. These chipsets will inevitably enter the device market quite soon and this probably will be considered as a good opportunity by the mobile operators willing to seamlessly enter 4G/LTE world. As LTE is not yet finished set of standards now, deploying IMS before 4G All IP Network will be in place, and using WiMAX as an access mode, may help operators to test their environment and then switch to AIPN more smoothly. At least, all the necessary technological background is in place for that.

WiMAX fits well in IMS infrastructure for several reasons. First of all, it is fast enough. Depending on the distance from the base station speeds up to 70 Mbits/s could be delivered, though the most common speeds in the city probably would be around 10 Mbits/s, which is almost as good as best-case HSDPA downlink speed right now. Mobile WiMAX (802.16e) offers mobility between base stations. Quality of service is guaranteed for each connection independently.

It looks like next years will show, whether mobile operators will use this opportunity, and would WiMAX be a “helping hand” for IMS deployment all over the world.