This blog entry is the second in a row about my thoughts on the current development of 4G wireless standards. You might want to take a look at the introduction before reading on.
The primary question when looking at future 4G systems is why there is or will be a need for them. Looking back only a couple of years, voice telephony was the first application that was mobilized. The short message service (SMS) was the first data application that was mobilized as a mass market application. By todays standards comparably simple mobile phones were required. Also, bandwidth requirements were very small. In a way, the SMS service was a forerunner for other data services like mobile eMail, mobile web browsing, mobile blogging, push to talk, mobile instant messaging and many others. These were enabled by the introduction of packet based wireless networks that could carry IP data on the one hand and more and more powerful mobile terminals that could cope with the requirements of these applications on the other. Today, current 3G and 3.5G networks are able to cope quite well with these applications as they offer a sufficient bandwidth per user. Also, network capacity is still not an issue as only few people use these services today. Having said that, there are a number of trends which are already visible today which will increase bandwidth requirements in the future:
- Rising use: As prices get more attractive, more and more people will use wireless networks for data applications. Consequently, bandwidth demand will rise.
- Multimedia content: While first attempts at mobilizing the web resulted in mostly text based web pages only, embedded images are now the norm rather than the exception. A picture says more than a thousand words but it also increases capacity requirements. Video and music downloads are also starting to become popular which again increase bandwidth requirements.
- Mobile Social Networks: Similar to the fixed line Internet, a different breed of applications is changing the way people are using the net. Before, users were mainly consuming content. Blogs as well as podcasts, picture- and video sharing sharing sites are reshaping the internet as users suddenly do not only simply consume content anymore but also create their own content which they want to share with others. Applications like Shozu and Lifeblog, for example, allow to create content on the mobile phone and upload them to the web in an easy fashion. Especially picture-, podcast- and video up- and downloading is multiplying the amount of data users send and receive.
- Voice over IP: The fixed line world is rapidly moving towards Voice over IP these days. I expect that in 5 years from now traditional fixed line circuit switched voice networks will be on a massive retreat and a fair percentage of users will use VoIP, e.g. over DSL or cable, as their primary fixed line voice service. The circuit switched market is already pretty much dead as operators are no longer investing in this technology. The same is happening in wireless, although there is one major issue: VoIP requires much more air interface bandwidth than the super slim voice codecs which are currently used for circuit switched voice calls over wireless networks. The air interface has been optimized on all layers of the protocol stack for circuit switched voice. The same is not possible for VoIP as the IP stack is a general data transmission stack and thus it can not be optimized for voice. The only solution is to increase the available bandwidth.
- Fixed line Internet replacement: Voice revenue in both the fixed line and the wireless market are on the decline. In many countries, operators are trying to compensate by offering Internet access for PCs, notebooks, etc. over their UMTS/HSDPA or CDMA networks. Thus, they have started to compete directly with DSL and cable operators. Again, this requires an order of magnitude of additional bandwidth on the air interface.
- Competition from alternative wireless Internet providers: In some countries, alternative operators are already offering wireless broadband Internet access with WiFi or (pre-)WiMAX 802.16d networks. Here’s an example of a small operator which offers wireless broadband access for a rural region in Austria. As such they directly compete with traditional UMTS and CDMA carriers who are also active in this market.
When combining these trends, it becomes quite clear why operators and standards bodies are pushing for ever faster wireless data networks.
In my next blog entry on this topic, I’ll take a look which technologies are competing for dominance in the 4G space. The most likely candidates to me are UMTS LTE, CDMA Rev-C and WiMAX.