DEPLOYMENT SCENARIOS

A major feature of WiMAX compared to other wireless access technologies is that it breaks the barrier of addressing a single customer profile. Global system for mobile communications (GSM)/universal mobile telecommunications system (UMTS) provide mainly voice and low speed internet to mobile subscribers, while local multipoint distribution service (LMDS)/wireless local loop (WLL) offer higher bandwidth services to fixed subscribers. WiMAX can offer broadband services to all fixed, nomadic, and eventually mobile subscribers, according to the aims of the latest IEEE 802.16e standard. This major advantage for WiMAX technology offers greater flexibility and scalability; however it presents more design challenges. A conceptual presentation of deployment scenarios, based on equipment, services, and potential customer profiles is presented in Figure 1. Each “sector” represents a WiMAX terminal profile:

• Fixed-outdoor units (including antenna, RF subsystem, modem), which can be installed on the rooftop or outer building walls for maximizing link performance. A cable connects the unit to an indoor interface terminal that provides Ethernet and VoIP ports.
• Fixed/portable indoor units (intergraded antenna, RF baseband and interface in a single box), which are installed indoors close to a window or the outer wall. The unit is portable within the indoor space, however it requires power supply.
• Nomadic/mobile units (PCMCIA cards, handheld devices), which are truly portable (mobile in future versions) and can be used in outdoor and indoor spaces.

 

Figure 1: Abstract of WiMAX deployment scenarios.

Each terminal profile is built with different performance capabilities and cost towards specific customer profiles. Fixed-outdoor terminals are capable of long range, robust links that can transfer high-bandwidth and delay sensitive services with low impact on network air-interface resources, hence they are more suitable for corporate, small-to-medium enterprises (SMEs), and small-offices-home-offices (SOHOs). The higher hardware and installation costs are balanced by higher revenues. Fixed-indoor terminals have considerably less cost and are self-installable, albeit with smaller link range. Such terminals address the mass market of residential access. Finally the nomadic and portable terminals require even greater network design margins and usually address individual customers at specific service areas (such as community/camp networks). Observing Section 1 it can be seen that business customers are likely to prefer a combination of fixed-outdoor and nomadic units, while residential and personal customers will probably select either a fixed-indoor or a nomadic unit. As WiMAX technology progresses, more system gain will be achieved in the air-interface thus resulting in higher cell ranges and increased percentage of nomadic terminals mainly at the expense of fixed-indoor units.

The continuous development of WiMAX technology from IEEE 802.16-2004 standard to the IEEE 802.16e amendment, has led to significant improvements in the air-interface. Recent advances include higher BS transmit power, advanced antenna systems (MIMO, beamforming (BF)), improved radio resource management through the OFDMA profile, improved coding techniques which reduce the signal-to-interference and noise ratio (SINR) thresholds, efficient uplink (UL) subchannelization, and flexible frequency reuse. The current amendment of WiMAX offers more than 15 dB increase in the system gain over previous versions which drastically extends the radio coverage, and can therefore reach indoor customers even when using portable/mobile terminals. As the WiMAX system gain increases due to the continuous enhancement of the air-interface, in the context of dimensioning, the network size for a specific deployment is reduced, and so is the up-front investment.

BENEFITS OF WiMAX

The WiMAX solution reflects the general trend in the communications industry toward unified packet-based voice and data networks. Fundamental benefits of this transition are reduced operation cost, improved network optimization, and better management of changes. The followings are some of the benefits of WiMAX.

Wireless. By using a WiMAX system, companies/residents no longer have to rip up buildings or streets or lay down expensive cables.

High bandwidth. WiMAX can provide shared data rates of up to 70 Mbps. This is enough bandwidth to support more than 60 businesses at once with T1-type connectivity. It can also support over a thousand homes at 1-Mbps DSL-level connectivity. Also, there will be a reduction in latency for all WiMAX communications.

Long range. The most significant benefit of WiMAX compared to existing wireless technologies is the range. WiMAX has a communication range of up to 40 km.

Multi-application. WiMAX uses the IP and is therefore capable of efficiently supporting all multimedia services from VoIP to high speed Internet and video transmission. It also supports a differentiated QoS enabling it to offer dynamic bandwidth allocation for different service types. WiMAX has the capacity to deliver services from households to small and medium enterprises, small office home office (SOHO), cybercafés, multimedia Tele-centers, schools and hospitals.

Flexible architecture. WiMAX supports several systems architectures, including point-to-point, point-to-multipoint, and ubiquitous coverage.

High security. The security of WiMAX is state of the art. WiMAX supports advanced encryption standard triple data encryption standard. WiMAX also has built-in VLAN support, which provides protection for data that is being transmitted by different users on the same BS. Both variants use privacy key management (PKM) for authentication between BS and SS station. WiMAX offers strong security measures to thwart a wide variety of security threats.

QoS. WiMAX can be dynamically optimized for a mix of traffic that is being carried.

Multilevel service. QoS is delivered generally based on the service-level agreement between the end user and the service provider.

Interoperability. WiMAX is based on international, vendor-neutral standard. This protects the early investment of an operator because it can select the equipments from different vendors.

Low cost and quick deployment. WiMAX requires little or no external plant construction compared with the deployment of wired solutions. BSs will cost under $20,000 but will still provide customers with T1-class connections.

Worldwide standardization. WiMAX is developed and supported by the WiMAX forum (more than 470 members). The WiMAX forum collaborates with different international standards organizations that are developing broadband wireless standards with the intent to provide interoperability among the standards. Some of the other broadband wireless standards include HiperMAN/HiperLAN (Europe) and WiBRO (South Korea). These standards are compatible with WiMAX at the physical layer. WiMAX will become a truly global technology-based standard for broadband and will guaranty interoperability, reliability, and evolving technology and will ensure equipment with very low cost.

VOIP AND IP | WIMAX APPLICATIONS

The WiMAX standard has been developed to address a wide range of applications. Based on its technical attributes and service classes, WiMAX is suited to supporting a large number of usage scenarios. Table 1 address a wide range of applications.

Table 1: Summary of WiMAX Applications 

Class Description	Real Time	Application Type	Bandwidth
Interactive gaming	Yes	Interactive gaming	50–85 Kbps
VoIP, video conferencing	Yes	VoIP	4–64 Kbps
		Videophone	32–384 Kbps
Streaming media	Yes	Music/speech	5–128 Kbps
		Video clips	20–384 Kbps
		Movies streaming	>2 Mbps
Information technology	No	Instant messaging	<250 byte messages
		Web browsing	>500 Kbps
		Email (with attachments)	>500 Kbps
Media content download (store and forward)	No	Bulk data, Movie download	>1 Mbps
		Peer to peer	>500 Kbps

Mobile WiMAX is an all-IP network. The use of OFDMA on the physical layer makes it capable of supporting IP applications. It is a wireless solution that not only offers competitive Internet access, but it can do the same for telephone service.

VoIP offers a wider range of voice services at reduced cost to subscribers and service providers alike. VoIP is expected to be one of the most popular WiMAX applications. Its value proposition is immediate to most users. Although WiMAX is not designed for switched cellular voice traffic as cellular technologies as are CDMA and WCDMA, it will provide full support for VoIP traffic because of QoS functionality and low latency. IPTV enables a WiMAX service provider to offer the same programming as cable or satellite TV service providers. IPTV, depending on compression algorithms, requires at least 1 Mbps of bandwidth between the WiMAX BS and the subscriber. In addition to IPTV programming, the service provider can also offer a variety of video on demand (VoD) services. IPTV over WiMAX also enables the service provider to offer local programming as well as revenue generating local advertising.