WIFI Comparison With Wimax

WiMAX is different from WiFi in many respects. The WiFi MAC layer uses contention access. This causes users to compete for data throughput to the access point. WiFi also has problems with distance, interference, and throughput and that is why triple play (voice, data, video) technologies cannot be hosted on traditional WiFi. In contrast, 802.16 uses a scheduling algorithm. This algorithm allows the user to only compete once for the access point. This gives WiMAX inherent advantages in throughput, latency, spectral efficiency, and advanced antenna support.

Companies developing radical innovations may adopt different stances not only based on the strategic interests of the company but also by taking into other considerations such as the market and its needs and requirements, as well as other products it may carry.

When comparing WiFi and WiMAX, one is comparing their substitutability and complementary to existing technologies and how different companies have and will view them. WiMAX and WiFi can offer some potentially significant cost savings for mobile network operators by providing an alternate means to backhaul BS traffic from cell site to the BS controllers. Mobile network operators typically utilize some type of wired infrastructure that they must buy from an incumbent operator. A WiFi or WiMAX mesh can offer a much more cost-effective backhaul capability for BSs in metropolitan environments.

Using WiFi and WiMAX open broadband wireless standards and implementing mobile computing, governments and partners can quickly and cost-effectively deploy broadband to areas not currently served, with little or no disruption to existing infrastructures. Standards-compliant WLANs and proprietary WiFi mesh infrastructures are being installed rapidly and widely throughout the world. Standards-compliant WiMAX products can provide NLOS backhaul solutions for these local networks and WiMAX subscriber stations can currently provide Internet access to customers such as schools and other educational institutions and campuses.

The results of the comparison show that mobile WiMAX has better performance in all the areas listed above (where it shares performance enhancing features with EVDO and HSDPA/HSPA). Furthermore, the technologies on which mobile WiMAX is based result in lower equipment complexity and simpler mobility management due to the all-IP core network. They also provide mobile WiMAX systems with many other advantages over CDMA-based systems such as

• Tolerance to multipath and self-interference
• Scalable channel bandwidth
• Orthogonal UL multiple access
• Support for spectrally-efficient TDD
• Frequency-selective scheduling
• Fractional frequency reuse
• Improved variable QoS
• Advanced antenna technology

1XEVDO Comparison With Wimax

This standard is developed by the third generation partnership project 2 (3GPP2), the body responsible for CDMA and EVDO. 1xEVDO is an enhanced version of CDMA2000-1x. There are four versions that have been released, namely, Rev. 0, Rev. A, Rev. B, and Rev. C.

1xEVDO is a high-speed data only specification for 1.25 MHz frequency division duplex (FDD) channels with a peak downlink (DL) data rate of 2.4 Mbps.

Improvements to CDMA2000-1x in the 1xEVDO Rev. 0 specification include:

• DL channel is changed from code division multiplexing (CDM) to time division multiplexing (TDM) to allow full transmission power to a single user.
• DL power control is replaced by closed-loop DL rate adaptation.
• Adaptive modulation and coding (AMC).
• HARQ.
• Fast DL scheduling.
• Soft handoff is replaced by a more bandwidth efficient “virtual” soft handoff.

1xEVDO Rev. 0, however, was designed to support only packet data services and not conversational services. In 1xEVDO Rev. A and EVDO Rev. C (also dubbed DORC), additional enhancements were added to the 1xEVDO specification. They include the following:

• DL: Smaller packet sizes, higher DL peak data rate (up to 3.1 Mbps), and multiplexing packets from multiple users in the MAC layer.
• Uplink (UL): Support of HARQ, AMC, higher peak rates of 1.8 Mbps, and smaller frame size

These enhancements in both the UL and DL of 1xEVDO Rev. A allow it to support conversational services.

COMPARISON WITH COMPETING TECHNOLOGIES

At some point current 2G and 3G network operators will migrate to a 4G network technology. Mobile WiMAX is likely to face competition from 3G and 4G technology enhancements. They include the code division multiple access (CDMA) variants CDMA2000 and wideband-CDMA (WCDMA) and their enhancements which are 1x evolution data optimized (1xEVDO) and HSDPA, respectively. Unlike in the early days of the CDMA vs. GSM competition, this higher generation competition will be quite different and fruitful because for these new generations networks; the applications are separated and do not depend on each other. 4G networks will go far beyond 2G and 3G by mainly improving three parameters:

• Interface technology: 4G standards will make a radical change and will use OFDM [9]. The new modulation itself will not automatically bring an increase in speed but very much simplifies the following two enhancements:
• Channel bandwidth: 4G systems will use a bandwidth of up to 20 MHz, i.e., the channel offers four times more bandwidth than channels of current systems. As 20 MHz channels might not be available everywhere, most 4G systems will be scalable, e.g., in steps of 1.25 MHz. It can therefore be expected that 4G channel sizes will range from 5 to 20 MHz.
• MIMO: The idea of MIMO is to use the multipath phenomena. Although this behavior is often not desired, MIMO makes active use of it by using several antennas at the sender and receiver side, which allows the exchange of multiple data streams, each over a single individual wave front. Two or even four antennas are foreseen to be used in a device. How well this works is still to be determined in practice but it is likely that MIMO can increase throughput by a factor of two in urban environments.

Increasing channel size and using MIMO will increase throughput by about 8–10 times. Thus speeds of 40 Mbps per sector of a cell are thus possible. Using a commonly accepted evaluation methodology for 3G systems, mobile WiMAX has been simulated against the 3G enhancements [23]. These simulations have shown that

• Mobile WiMAX peak data rates are up to 5x better than 3G+ technologies.
• Mobile WiMAX spectral efficiency is 3x better than any 3G+ technology.
• Lower equipment cost for WiMAX due to certified products (compare with WiFi).
• WiMAX requires new infrastructure while high-speed packet access (HSPA) rides on UMTS.
• Roughly the same coverage (average ~5 km).
• Roughly the same performance (average ~2 Mbps per user).
• HSDPA launched in 2006 while HSUPA will come in 2008.
• WiMAX standard set end of 2005 and first products in 2006.
• HSPA has a higher acceptance with mobile operator.

APPLICATION PROVIDERS & WIMAX CUSTOMERS

APPLICATION PROVIDERS

WiMAX has already revolutionized the broadband wireless market by standardizing broadband wireless access market, by opening up new service opportunities and by creating the environment for ubiquitous broadband services.

The aim is to provide the service that best fits the individual’s needs. Applications can be developed in house by the service providers, outsourced from other companies or developed and sold directly to the end user by an independent applications development company.

Applications are based on IP, and IP applications are sent back or forth via WiMAX. This allows the users to develop applications independently from the underlying network infrastructure. Some applications will still be developed by operators but the vast majority will come from those working directly in the Internet crowd. For them and for the end users competing wireless technologies are very beneficial. Competition spurs network roll outs, offers possibility for new players in the market, and creates competition between device manufacturers. Also, new applications will be introduced more easily and much more quickly as they are no longer forced into a tight framework that takes long time to develop and from which it is difficult to get out again.

WIMAX CUSTOMERS

Prospective WiMAX customers can be grouped either geographically or by the level or volume of services. Geographical categories range from urban to rural customers, while categories according to size include individual customers and the corporate customers. Urban areas offer the highest density of customers with more business establishments. In such cases a higher number of cells which are small in size are required to meet the capacity requirements. These are the areas where more competition is expected. Rural areas are expected to have a lower penetration of customers, less corporate customers, and bigger cell sizes because emphasis is on coverage rather than capacity. Individual subscribers will use WiMAX for music downloads, interactive gaming, and personal broadband Internet, and will form a large percentage the total subscribers.

Corporate subscribers are also expected to contribute to revenues of WiMAX, and their interest will be in applications and services which will enhance their organizations apart from the basic telecommunications services.

Companies are poised to compete with each other in WiMAX network deployment, which will ensure that the prices will be competitive

WIMAX SERVICE PROVIDERS

As IP networks become faster (higher bandwidth) and more responsive (lower delay), the set of services implemented on IP-based networks has grown. This growth generates more revenue opportunities for service providers, and thus next-generation networks are all migrating toward IP technology. From an operator standpoint, services can be broken into four billable classes: 

(1) basic Internet services which are typically billed at a flat rate, 

(2) premium Internet services which are important not only to improve ARPU, but to add new services, 

(3) VPN services which can be billed by QoS level, and 

(4) operator premium services which are applications provided on the operator’s network.

The service providers are expected to gain profits through the sale of the different services and applications that WiMAX is capable of carrying. The different services that can be offered on WiMAX networks include best effort VoIP, carrier class IP telephony through the IP multimedia core, music, video conferencing, streaming video, interactive gaming, mobile instant messaging (IM), IP television (IPTV), basic broadband wireless Internet, and other application-based services to corporate customers. The concept of unbundling the network reduces the barriers of entry into the mobile telecommunications industry because a provider does not need to own the whole network.

The business aspect of the service providers can also be looked at from two perspectives. The first one is where the service provider owns the whole system including the core network and the access network. The second option is the unbundled option where the access network and core networks exist as independent business entities.

In emerging markets such as Africa, and South Asia where telecom investment is still nascent and 3G yet to be launched, WiMAX makes complete business sense even at equal cost, better speeds, better spectrum utilization, and the promise of broadband to a much sparsely spread population. For developed economies, the United States for instance, the 2.3 spectrum band is believed to be more capex efficient and hence better than 3G and high-speed uplink packet access (HSUPA). More importantly, the phase in the capex cycle of a telecom operator will determine each operator strategy—whether to embrace WiMAX or stick to its existing technology. The WiMAX industry entered the year 2007 as a year for ecosystem buildup in the preparation for regional and nationwide deployments of WiMAX services. It appears that 2008 will be a make-or-break period for WiMAX. Figure 1 shows a global WiMAX deployment by region.

 

Figure 1: Global WiMAX networks. APAC = Asia Pacific, CALA = Caribbean and Latin America.

WIMAX EQUIPMENT VENDORS

WiMAX, as with many new technologies, is based on an open standard. Although standards increasingly play a crucial role in driving adoption, they are not sufficient to guarantee success. A standard-based technology will success only if a solid ecosystem of operators, vendors, and solution and content providers emerge to support it, as is in the case of WiMAX. WiMAX enables intervendor interoperability which brings lower costs, greater flexibility and freedom, and faster innovation to operators.

Within the WiMAX industry there is a strong commitment to ensuring full interoperability through certification and ad-hoc testing between vendors. It is important for network operators to realize how interoperability is established and what it covers so that they understand how different products, solutions, and applications from different vendors can coexist in the same WiMAX network. The advantages that interoperability brings are multiple. Some of these advantages are the ability to choose among vendors, flexibility when choosing the appropriate network elements and components, success to the latest cutting-edge technology, and an open architecture which makes it easier for operators to roll out new revenue-generation services and applications as they can rely on wider pool of suppliers.

The two categories of equipment vendors include the network equipment vendors and the terminal equipment vendors. Network equipment includes ASN and CSN equipment, and vendors include companies such as Motorola and ZTE of China. They will gain their profits through the sale of the equipment and through installation of the equipment. They may further have after sales agreements with the customers who are the service providers. Terminal equipment includes mobile phones, CPE, modems, laptops, smart phones, and PDAs and they are manufactured by companies like Nokia, Blackberry, Motorola, and Intel. They will gain their profits through the sale of the terminal equipment. Nokia, the world’s top handset maker, expects to start selling cell phones using the WiMAX technology in 2008.

THE WiMAX BUSINESS MODEL

The biggest challenges to deploying WiMAX-based services are business related. Carriers need financial capability to implement infrastructure. Each operator has to carefully identify its own requirements, dictated by the type of services offered, the market segments targeted, the spectrum available, and the topography of the coverage area. There is no single solution that works for all, and operators need to make key choices about the management and core networks as they plan for their WiMAX networks.

An accurate business case analysis must take into account a wide variety of variables such as demographics, services, frequency band alternatives, capital expense items, operating expense items, and CPE equipment. The WiMAX business model can be looked from several perspectives. These include the equipment vendors, service providers and application providers, and customers. WiMAX will have a larger impact long term than we have seen from cellular phones in the past two decades. Initial rollouts of WiMAX will begin mostly by competitive local phone service carriers and rural Internet service providers. Larger carriers will utilize fixed WiMAX to deliver services to residential customers many of whom are in underserved markets. WiMAX adoption in these underserved markets will be high due to lack of availability of high-speed data access. These deployments will generate capital to be reinvested for future deployments. Larger customer base will begin driving both the cost of carrier and customer equipment down. As the economy of scale makes deployment less expensive, mobile platforms will begin to appear. This development will be spread between high population centers and the rural markets that already have fixed platforms deployed. Fixed platform will act as a springboard for mobile deployment. Then interconnections will begin to form between rural markets and metropolitan markets as carriers from cooperative agreements to share network resources. The economy of scale will increase exponentially at this point and we will notice a negative impact on traditional cellular, Internet, and voice services. Once the implementation of initial hot underserved rural markets and high-density metro areas is completed, springboard deployments will quickly take WiMAX coverage to the level of coverage offered by traditional wireless today. This process will move much faster than the deployment of cellular networks and devices for the following key reasons:

• Manufacturing process for WiMAX devices will be quite similar to that of wireless devices and mostly the changes will be in components and software.
• Readiness of the current wireless fixed and mobile market and waiting on new technology.
• As carriers built out wireless networks, most of the questions in this field have been answered and can now be applied to the development of a mirror network that provides WiMAX access.