The Science of Mobile WiMAX Technology

The following resources contain additional information on Wimax. Please use them to get more in-depth knowledge on this topic.

WiMax Technology − Good site to give latest information on Wi-fi and WiMax.

WiMAX Forum − Official website of WiMAX Forum, the best resource for WiMAX  information.

IEEE 802.16 Specification − The IEEE 802.16 Working Group on Broadband Wireless Access Standards.

WiMAX tutorial − Tutorial to understand the concepts related to WiMAX.

WiMAX Industry − Find latest news and market trends about WiMAX.

Finally we are at a safe vantage point to decide whether the WiMAX storm will survive and rise or be remembered as mentioned above “an archaeopteryx”- the first of its kind now which we read in literature only. Nevertheless its the consumer or the person involved with this tech who will have the final say if it’s a hit or miss. I will try to present my conclusion standing on turn at two banks of a river and see which way it flows.

The future of WiMAX- Trends and possibilities

What do a poor farmer in a remote village in Africa and a rich business man from Manhattan will have in common? Both will benefit from the coming revolution of mobile WiMAX, the fourth generation of wireless technology. The farmer will be able to speak on a cheap cell phone for a price he can afford—even at a distance of many kms from his village, due to the increased coverage and low-cost services WiMAX can offer. The rich business man will be able to use continuous, pervasive, high-speed mobile internet service from his notebook PC in his office, on the way to a cafe, or in the subway. Sounds exciting, isn’t it.

All advanced features challenge WiMAX equipment manufacturers to build strong, dedicated, low-cost low power WiMAX base stations and chipsets for the portable units for advanced handsets and PC peripherals (PC cards or USB dongles) and other consumer electronics devices as game terminals. This is one main bottleneck to an expansive growth of the technology.

This is technical problem which can be resolved sooner or late, but the real danger is from the competing technologies. LTE is one such technology which has been pushed aggressively in all developed markets. Andrew Schmitt, founder of technology analyst firm Nyquist Capital, says he is following wireless network market trends more than technological specifics He isn’t convinced that WiMax’s technological promise will deliver mobile market benefits above and beyond competing technologies. “You have a limited number of suppliers who are pushing WiMax,” Schmitt says, “and it isn’t clear to me that they’re doing it because they really believe in it, or because they’re rolling the dice that it will be successful, and they’ll have a head start. I haven’t seen anybody make a really strong case for why it’s so much better than LTE. 

Analyst firm In-Stat’s Daryl Schoolar says the fact that both Wi-Fi and WiMax come from the IEEE 802 family gives the newer technology a certain amount of recognition and credibility among consumers — as borne out by the survey results — but that it also presents a dilemma for providers.

“Most people don’t care about the technology in their network,” he says. “They just care that they can download something they want fast. So how are the operators going to do WiMax? Is it just going to stealthily work its way into the phone, like 3G has in many ways, and it’s just kind of there? Or are they going to try to do something different with it? I would think it’s important for WiMax that they somehow differentiate it.”

So we can see here, there is differentiated opinion among people about the whole idea of WiMAX. WiMAX is trying to stronghold the developing nations. In Asia, Taiwan is considered a leader in the development and deployment of WiMAX operability with six commercial WiMAX licenses awarded in July 2007 to six separate Taiwanese wireless communication providers. In the Pacific, in countries like Australia, WiMAX technology is perfectly suited for regional and rural areas with geography challenges and limited wireline footprints. In Africa, which has many developing countries, WiMAX technology provides the opportunity to connect the African people with internet and VOIP services faster and more affordable than wireline.

But at the same time LTE is wooing the Crème dela crème in north American market and European market. There is a strong lobby of companies on both sides. It’s a matter of time one technology overtakes the other but currently the swing is in favour of LTE.

“It's not the size of the dog in the fight, it's the size of the fight in the dog.” – Mark Twain

Wi-Fi, WiMAX, and LTE are hot wireless technologies currently experiencing an enormous increase in deployments, products and services -- but they're also easily confused. We will try to examine the difference between the technologies in terms of standards development and see for yourself which one suits your business.

Mobile WiMAX is a relatively new technology as compared to already established ones like WiFi, 3G,WLAN, DSL, etc. It has to fight for its place among the so called communication giants in order to earn the trust of consumer as a technology of future. It is already clear from previous discussions WiMAX is a much advance technology as compared to WiFi or 3G-LTE but the fact is that it has been a difficult technology to realise in practical scenario till date.

I will be presenting here a comparative analysis of WiMAX and various wireless technologies present in the market. Let’s see if the comparable technologies actually complement each other or are at faceoff situation.

WiFi VS WiMAX- COMPLEMENTARY OR “ITS” COMPLICATED!!!

WiMAX is similar to the wireless standard known as Wi-Fi, but on a much larger scale and at faster speeds.  WiMAX is different from Wi-Fi in many respects. In fact, Wi-Fi can operate at distances as great as WiMAX but there are two reasons why it doesn't. One of the reasons is that radios operating in the unlicensed frequencies are not allowed to be as powerful as those operated with licenses; and from convention, less power means less distance. Wi-Fi even has problems with interference, and throughput and that is why triple play (voice, data, and video) technologies cannot be hosted on traditional Wi-Fi. In contrast, 802.16 use a scheduling algorithm (Xu, et al., 2006). 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. From the technical point of view, it can be seen that both of these two wireless technologies are not basically addressed at the same market but are very complementary. Wi-Fi is basically an implementation of wireless local area network within a short range like a small building, a college or an institutional campus. WiMAX on the other hand is a metropolitan technology whose objective is to interconnect houses, buildings or even hot spots to allow communication between them and with other networks.  The table below gives a detailed comparison between WiFi and WiMAX.

Conclusion for WiFi or/plus WiMAX- The bigger picture

In Summary, WiMAX technology represents a quantum leap in the ability to propagate wireless connectivity with acceptable speed, allowing the technology to be used as a business class access technology. But the bottom line is that WLANs and WMANs are complementary network architectures, supported by standard technologies that were designed for very different environments and purposes. This is why your next laptop may well include both Wi-Fi and Mobile WiMAX adapters. Use the Wi-Fi adapter to connect to your office or home WLAN free-of-charge, but use the WiMAX adapter when you're on the go to reach the Internet through a carrier's WMAN.

WiMAX VS LTE –SHOULD YOU SWITCH?

The WiMAX vs WiFi battle seems to be more in favor of WiMAX. But WiMAX vs LTE is a different ballgame. LTE is a much improved technology as compared to WiMAX and, was launched and publicized very aggressively by 3GPP as a true 4G technology. The "4G" moniker is officially meaningless, but WiMAX was the first technology to call itself 4G when Sprint announced it back in 2006. Shifting our attention to mobile WiMAX, it was launched by Sprint in 2008 with a promise of twice as fast as then existing 3G network(1 Mbps). Unfortunately, Sprint squandered its lead by building its network very slowly. In 2006, WiMAX would have been a revelation, but the first city didn't go live until 2008. This made the whole cell phone industry turn away from WiMAX (and Intel) to LTE, which came from the same folks who brought us GSM and promised much better compatibility with existing cell phone equipment.

WiMAX and LTE Similarities

Before going in WiMAX vs LTE duel, let’s check their similarities. Both these 4G technologies are quite similar. Check below the similarities: • They are both all IP technologies • They both support advanced MIMO – multiple input and multiple output antenna technology • They both use similar modulation technology based on OFDM – orthogonal frequency division multiplexing.

WiMAX vs LTE Differences

Beside similarities, WiMAX and LTE also have many differences: • LTE-A uses different channels bandwidth from 1.4 MHz to 100 MHz, while WiMAX uses channels bandwidths up to 40 MHz • LTE uses different modulation for uplink (SC-FDMA) and downlink (OFDMA), while WiMAX uses the same modulation for both uplink and downlink – SOFDMA • LTE frame duration is 10 ms, WiMAX is 5 ms • LTE-A can handle speeds up to 450 km/h or 280 mph, while WiMAX 120 km/h or 75 mph • WiMAX network doesn’t support legacy systems like 2G and 3G, while LTE is compatible and enables coexistence and roaming between LTE and 3G. • Cost for building WiMAX network is lower than cost for building LTE network.

LTE Advantages over WiMAX

• LTE is compatible with previous mobile technologies – GSM, GPRS, UMTS, EDGE, WCDMA, HSPA, CDMA-one, CDMA2000, EV-DO, EV-DV and the synchronous SC-CDMA • Enables much greater speed for the mobile users – speed up to 450 km/h or 250 mph • Better technology for power consumption of mobile terminals – it uses SC-FDMA for uplink – modulation technology that saves battery life of mobile terminals • LTE-A is only true 4G technology.

WiMAX Advantages over LTE

• Deployment of WiMAX network is much cheaper than deployment of LTE network • Great choice for private mobile broadband wireless networks To sum up the comparison we can have a quick look at the table below.

The Conclusion of WiMAX vs LTE – Which 4G Technology is Better

The LTE is much more popular and widespread than WiMAX and the big majority of the mobile operators will chose the LTE as its 4G technology. One of the biggest advantages of LTE over WiMAX is its compatibility with all previous mobile technologies GSM, GPRS, UMTS, WCDMA, CDMA, CDMA200, EV-DO. WiMAX is compatible with the previous version of WiMAX that were not used as mobile technologies.  It is also important to mention that the latest LTE standard, LTE – Advanced or LTE-A, is the only true 4G technology. WiMAX is a better choice for the low cost installing network in developing countries, wireless replacement for the DSL, private networks in dedicated industrial segments.

As we can conclude from above , you have all the technology with you. Its upto you what you want to select. LTE seem to lead the race in cellular broadband service in developed countries but WiMAX can be poor man’s LTE in developing countries. WiFi still holds its ground firm as a fixed broadband service and be clubbed with WiMAX to give it a more robust outlook.

From the wisdom words of Mark Twain, the one that has the desire to fight till last will triumph others will perish

Reference

We are nearly there!!! Just to recap till now we know what is WiMAX. What are the types of WiMAX technologies available? What is mobile WiMAX technology protocol (802.16e), how it originated and the system profile. But still a very important question looms. Is it worth the money and hype. What are the advantages and disadvantages of this technology. Let’s look into the two sides of coin. 

WiMAX is one of the latest wireless technology designed to enable high-speed mobile Internet access to devices including notebook PCs, mobile phones, gaming devices, and more. It is known as fourth generation (4G) wireless technology as it outruns 3G technology by means of data transmission and coverage area that reaches a very large geographical areas, even entire cities and regions. This means no more to roam the streets looking for the best Wi-Fi signal. But as usual, every next gen technology brings with it a more complicated set of networks, communication protocols and a set of practical difficulties which are far from idealistic conditions. Let’s move our attention about practical disadvantages of WiMAX technology. An ideal stats shows that WiMAX can offer 70 Mbps in range of 70 miles with moving stations which is far from practice situation. One could have with line-of-sight (optical visibility) speed of 10 Mbps at 10 km. The cell breathing space reduces further more in case of urban setup to 10 Mbps for 2Km. If the user in motion there is further drop in speed. Since we cannot have a single person sharing the channel, a considerable number of user sharing the same channel degrades the speed to a very low value. Mobile WiMAX technology is based on high speed data transmission across handheld devices. This involves installation of sophisticated transceivers which are capable of such ultrahigh data transmission handling at very low power. This brings huge signal processing and maintenance cost to the equation. This is also one of the main stumbling blocks to the realization of WiMAX. So let's put on paper WiMAX advantages and disadvantages. Advantages: • Provides mobility to user with access to the Internet. • Convenient to user because of the ubiquitous connection. • High speed radio wave data transmission (up to 10Mb). • Does not require telephone line. • Designed with better quality of service (QoS) • Non-line of sight connection. • It is standardized, and the same frequency equipment should work together.

Disadvantages: • Line of sight is needed for longer connections. • Weather conditions like rain could interrupt the signal. • Other wireless equipment could cause interference. • New technology which is still unstable, frequent disconnections. • WiMAX is very power intensive technology and requires strong electrical support. • Connection weakens when distance increases, away from transmission tower.

As we can see above, grapes can be sour. So before buying this technology one has to realize what the important conditions that he wants are. Everyday life we have been bombarded by the need for access to instant, entertainment information and communications 24 / 7. With today’s busy lifestyle, fast and on-the-go way, this can be the shining armor to possess. But to its flip side, it’s an expensive chocolate to have. Added to it are the high drain quotient of your mobile battery. So, the onus is on readers how they take this technology!!! DECIDE FOR YOURSELF

References:

Till Now we have an introduction on what is WiMAX. WiMAX as a whole encompasses a wide range of communication protocols. Since it’s difficult to cover everything, in this blog I will narrow down my approach to mobile WiMAX technology protocol i.e. 802.16e. Let’s dive deep into the world of Mobile WiMAX to know more about it.

As soon as we see mobile WiMAX, an obvious question pops to our head - Is there a fixed WiMAX also? If yes how both are different? I will try to give a give a justification to it. After that we can will go more into details of mobile WiMAX and its mode of operations.

To give a headstart, there is just one common point between 802.16d fixed WiMAX and 802.16e mobile WiMAX – they share the same last name. Beyond that there is virtually no relevant relationship between the two technologies. 802.16d was developed for the sole purpose of linking the “last mile” to the home or enterprise that has long been the gap between broadband Internet “haves” and “have nots”. There is no viable competitive technology to fixed WiMAX for providing last mile connectivity other than some proprietary solutions like Motorola’s Canopy. 802.16e was developed to compete with existing cellular solutions and to expand mobile voice services by adding high-speed mobile data services[1].  I am restricting the protocols just to definition. Moving forth I will discuss only about “802.16e mobile WiMAX”.

How Mobile WiMAX came into existence

In December, 2005 the IEEE ratified the 802.16e amendment to the 802.16 standard. This amendment adds the features and attributes to the standard necessary to support subscriber stations moving at vehicular speeds. The WiMAX Forum is now defining system performance and certification profiles based on the IEEE 802.16e Mobile Amendment and, going beyond the air interface, the WiMAX Forum is defining the network architecture necessary for implementing an end-to-end Mobile WiMAX.

Mobile WiMAX is a broadband wireless solution that enables convergence of mobile and fixed broadband networks through a common wide area broadband radio access technology and flexible network architecture. The Mobile WiMAX Air Interface adopts Orthogonal Frequency Division Multiple Access (OFDMA) for improved multi-path performance in non-line-of-sight environments. Scalable OFDMA (SOFDMA) is introduced in the IEEE 802.16e Amendment to support scalable channel bandwidths from 1.25 to 20 MHz. The Mobile Technical Group (MTG) in the WiMAX Forum is developing the Mobile WiMAX system profiles that will define the mandatory and optional features of the IEEE standard that are necessary to build a Mobile WiMAX-compliant air interface that can be certified by the WiMAX Forum. The Mobile WiMAX System Profile enables mobile systems to be configured based on a common base feature set thus ensuring baseline functionality for terminals and base stations that are fully interoperable.

FEATURES OF STATE OF ART MOBILE WiMAX TECHNOLOGY

Mobile WiMAX products and certification follow the IEEE 802.16e air interface specifications. The figure below gives a more detailed view of the construction of the mobile WiMAX system profile from the air interface perspective. The system profile is composed of five subprofiles, namely, physical layer (PHY), media access control (MAC), radio, duplexing mode and power classes. Even though there are many different combinations of center frequencies and channel bandwidths accommodating different regional spectrum regulations, all Release 1 mobile WiMAX products share the same PHY and MAC features (profiles) and the same duplexing mode which is Time Division Duplex (TDD). In the following, some detailed descriptions of key PHY and MAC features in the mobile WiMAX system profile are offered.

PHYSICAL LAYER

In the following we give the key PHY features of mobile WiMAX technology and provide short descriptions.

OFDMA Basics

Orthogonal Frequency Division Multiplexing (OFDM) is a multiplexing technique that subdivides the bandwidth into multiple frequency sub-carriers. In an OFDM system, the input data stream is divided into several parallel sub-streams of reduced data rate (thus increased symbol duration) and each sub-stream is modulated and transmitted on a separate orthogonal sub-carrier. The increased symbol duration improves the robustness of OFDM to delay spread. OFDM exploits the frequency diversity of the multipath channel by coding and interleaving the information across the sub-carriers prior to transmissions. OFDM modulation can be realized with efficient Inverse Fast Fourier Transform(IFFT). Orthogonal Frequency Division Multiple Access (OFDMA) is a multiple-access/multiplexing scheme that provides multiplexing operation of data streams from multiple users onto the downlink sub-channels and uplink multiple access by means of uplink sub-channels.

The OFDMA symbol structure consists of three types of sub-carriers:

Data sub-carriers for data transmission

Pilot sub-carriers for estimation and synchronization purposes

Null sub-carriers for no transmission used for guard bands and DC carriers

The WiMAX OFDMA PHY supports sub-channelization in both Downlink and Uplink. The minimum frequency-time resource unit of sub-channelization is one slot, which is equal to 48 sub-carriers.

Scalable OFDMA

The IEEE 802.16e-2005 Wireless MAN OFDMA mode is based on the concept of scalable OFDMA (S-OFDMA).S-OFDMA supports a wide range of bandwidths to flexibly address the need for various spectrum allocation and usage model requirements. The scalability is supported by adjusting the FFT size while fixing the sub-carrier frequency spacing at 10.94 kHz. Since the resource units sub-carrier bandwidth and symbol duration is fixed, the impact to higher layers is minimal when scaling the bandwidth. It supports adaptive modulation and coding, so that in conditions of good signal, a highly efficient 64 QAM coding scheme is used, whereas when the signal is poorer, a more robust BPSK coding mechanism is used. In intermediate conditions, 16 QAM and QPSK can also be employed.

Other Advanced features of PHY layer

Adaptive modulation and coding (AMC), Hybrid Automatic Repeat Request (HARQ) and Fast Channel Feedback (CQICH) were introduced with Mobile WiMAX to enhance coverage and capacity for WiMAX in mobile applications. The combinations of various modulations and code rates provide a fine resolution of data rates. WiMAX provides signalling to allow fully asynchronous operation. The asynchronous operation allows variable delay between retransmissions which gives more flexibility to the scheduler at the cost of additional overhead for each retransmission allocation. HARQ combined together with CQICH and AMC provides robust link adaptation in mobile environments at vehicular speeds in excess of 120 km/hr.

MAC LAYER

The 802.16 standard was developed from the outset for the delivery of broadband services including voice, data, and video. The MAC layer is based on the time-proven DOCSIS standard and can support bursty data traffic with high peak rate demand while simultaneously supporting streaming video and latency-sensitive voice traffic over the same channel. The resource allocated to one terminal by the MAC scheduler can vary from a single time slot to the entire frame, thus providing a very large dynamic range of throughput to a specific user terminal at any given time.

Quality of Service (QoS) Support

With fast air link, asymmetric downlink/uplink capability, fine resource granularity and a flexible resource allocation mechanism, Mobile WiMAX can meet QoS requirements for a wide range of data services and applications. The service flow based QoS mechanism applies to both DL and UL to provide improved QoS in both directions. Mobile WiMAX supports a wide range of data services and applications with varied QoS requirements.

MAC Scheduling Service

The Mobile WiMAX MAC scheduling service is designed to efficiently deliver broadband data services including voice, data, and video over time varying broadband wireless channel.

Mobility Management

Battery life and handoff are two critical issues for mobile applications. Mobile WiMAX supports Sleep Mode and Idle Mode to enable power-efficient MS operation. Mobile WiMAX also supports seamless handoff to enable the MS to switch from one base station to another at vehicular speeds without interrupting the connection.

Security

Mobile WiMAX supports best in class security features by adopting the best technologies available today. Support exists for mutual device/user authentication, flexible key management protocol, strong traffic encryption, control and management plane message protection and security protocol optimizations for fast handovers.

References:

Each passing decade bring to us technologies that seem this is it. But the story doesn’t end there. Evolution is the only constant fact and, continuous research and development are pushing the barrier of our knowledge, understanding and technical advancement. WiMAX was one such technology when officially standardized in 2004 took the communication world by storm. It led to development of new IEEE standards and modification of previously authored ones. To add Mobile WiMAX technology proved to be an another milestone development. Is it really worth the buzz? Is it a hit or miss? How is it different? I will touch base the WiMAX technology as a holistic viewpoint  and do an in-depth analysis of IEEE 802.16E mobile WiMAX technology Standard. By the time we reach to an end, let’s hope we have the answers!!!

What is WiMAX?

The first question that will hit any genuine mind is “what is WiMAX?”. Let’s start from the start. WiMAX stands for Worldwide Interoperability for Microwave Access. WiMAX technology enables uninterrupted flow of wireless data over long distances for fixed and/or mobile users. The term WiMAX was coined by the WiMAX forum, a non-profit organization, having more than 600 member companies. The primary purpose of this forum is to ensure interoperability among IEEE 802.16 based products through its certification process [1]. IEEE 802.16 standards provides specification for wireless metropolitan area (MAN) networks. WiMAX can be seen as a subset to IEEE 802.16 standards but commercially it represents the Wireless MAN family of standards. WiMAX is directed to the advancement of IEEE 802.16 standards for broadband wireless access (BWA) networks. IEEE 802.16 family of standards have evolved leaps and bounds during the recent years or to be precise late 2000s’. I cannot cover all the standards. I will be restricting my focus to IEEE 802.16E standards. Just to give a brief idea, IEEE 802.16e specifies the framework for current mobile WiMAX technology. It is the first wireless protocol to standardize mobility based on orthogonal Frequency Division Multiplexing Access (OFDMA).

To give a sneak peak to future posts, I will be discussing at length the about, features, operations,  advantages and the future scope for IEEE 802.16e standards.

A short video presentation on WiMAX Technology.

Till then Signing Off!!! And ‘DHANYAWAD’ for reading.