WiMAX: Technology for Broadband Wireless Access

16.3 Comparison Between WiMAX and 3G

Table 16.2 gives some comparison elements between major wireless systems: the second-generation cellular system GSM, in its EDGE evolution, 3G UMTS, WiFi in its two variants. 802.11b (the original WiFi) and 80.11a (including OFDM transmission), and WiMAX.

In order to compare with cellular 3G networks, only Mobile WiMAX is considered, since Fixed WiMAX represents a market completely different from 3G. The advantages of each of the two systems are highlighted, starting with the older one, cellular 3G.

16.3.1 Advantages of the 3G Cellular System

• WiMAX uses higher frequencies than Cellular 3G, which mainly operates in the 1.8 GHz range. Received power decreases when frequency increases and wireless system transmitted powers are often limited due to environmental and regulatory requirements. WiMAX ranges are globally smaller than 3G ranges. This is the case for outdoor and indoor equippments. However, the cell range parameter is often not the most limiting one in high-density zones, where the main part of a mobile operator market is located.

• 3G is already here. Its equipment including the high-data rate High-Speed Downlink Packet Access (HSDPA) networks and products are already used, since 2005 in some countries. Globally, 3G has a field advance of two to three years with regard to WiMAX. Will it be enough for 3G to occupy a predominant market share?

• The WiMAX spectrum changes from one country to another. For example, a WiMAX user taking equipment from country A to country B will probably have to use a different WiMAX frequency of the operator of country B. On the other hand, making multifrequency mobile equipment, for a reduced cost, is now becoming more and more easy for manufacturers.

• Some countries have restrictions on WiMAX frequency use, i.e. WiMAX operators can be forbidden to deploy mobility by the regulator.

• Cellular 3G has long had the exclusive support of leading manufacturers, such as Nokia. These companies now seem to be interested in WiMAX while also still remaining very interested in 3G.

16.3.2 Advantages of the (Mobile) WiMAX System

• The frequency spectrum of WiMAX should be cheaper than 3G system frequencies in many countries. The UMTS licence sales in Europe, and specifically in Germany and the UK, reached surprisingly high amounts.

• WiMAX is a very open system as frequently seen in this book: many algorithms are left for the vendor, which opens the door to optimisation, and connections between different business units operating on different parts of the network (core network, radio access network. services providers, etc.), possibly in the same country, are made easy (see Chapter 13). This is probably an advantage, but perhaps it might create some interoperability problems in the first few years?

• The WiMAX PHYsical Layer is based on OFDM, a transmission technique known to have a relatively high spectrum-use efficiency (with regard to SC CDMA). There are plans to upgrade 3G by including OFDM and MIMO in it. This evolution is called, for the moment. LTE (Long-Term Evolution). This gives a time advance for WiMAX in the implementation ofOFDM.

• WiMAX is an all-IP technology. This is not the case for the 3G system where many intermediate protocols (tunnelling, etc.) made for the first versions of 3G are not all-IP. However, evolution of 3G should provide end-to-end IP (or all-IP).

• WiMAX has a strong support of some industry giants, such as Intel, KT, Samsung and many others.

Taking into account all these observations, it is very difficult to decide between the two systems. However, if we want to make a guess, it could be said thnt there is a place for both of these two technologies, depending on the market, the country and the application … at least for a few years to come!