Marching cubes

Marching cubes

7. Is UWB Technology on the Road To Success?

To evaluate the current standing and see future forecast of the UWB Technology, I use recent research results from two research institutions: ABI Research and In-Stat Research.
Since these institutions are not particularly linked to UWB and do researches for general communications, the results of their research can show unbiased forecasts.

Results from ABI Research
According to the ABI Research, UWB should see "very strong growth" starting in 2008, finding its first success in laptops, computer peripherals and eventually in mobile handsets. Forecasts indicate that shipments of UWB-enabled devices will grow from virtually zero today, to more than 400 million in 2013.
Owing to the different challenges facing UWB i discussed in section 6, the UWB market did not come out as anticipated. But the research result shows that the conditions are now ripe for a rapid takeoff. In 2007 only about 40,000 UWB-equipped devices shipped. The research result also forecasts that in 2008, there will be perhaps 1 million, with the curve expected to rise sharply thereafter. Because an official UWB standard has now been ratified in the U.S., North America is expected to lead this market for some time to come.
The current "sweet spot" in this market is UWB's application as a wireless Universal Serial Bus(USB) enabler, connecting computers (specially notebooks) with printers, hard drives and other peripherals. Also UWB modules are just starting to appear in selected laptops (initially from Lenova, Dell and Toshiba) , but true silicon integration will take more time.
According to this same research, real market acceleration will only occur when UWB debuts in mobile handsets, where it will be used- possibly bundled with Bluetooth- to transfer music, pictures and video files. Even a small handset market penetration will deliver huge numbers. For UWB to see wide adoption in handsets, however, the price of the chipset must fall quite significantly.

Research results from In-stat
According to this research, the market for UWB silcon has finally began to take off in 2007. Though regulatory hurdles over UWB still persist worldwide , the first UWB-enabled ntebook PCs have shipped this year from Dell , Levano, and Toshiba.
UWB is a very flexible technology in that it supports multiple standards, including WUSB , Bleutooth 3.0 , IP over UWB , and Video over UWB. This should enable the technology to gain design wins in a wide range of product segments , including PC peripherals, Consumer Electronics (CE) , and mobile phones.
Recent Research by In-Stat found the following:

• UWB-enabled notebook PCs hit the market in mid-2007. PC peripherals will follow in this year (2008)
• CE and communications applications with UWB won't hit the market in volume until 2010.
• In 2011, over 400 million UWB-enabled devices will ship.
  

Finally, let me give some of the comments made by the Stephen wood, president of the WiMedia Alliance, on their current and future strategy.
The first phase of UWB products focuses on getting the technology in to market. That is why the first products are dongles, hubs and laptops. The next phase will bring lower prices and broader market opportunities as a 2-chip UWB solution is replaced with 1-chip silicon. In the next two years the Alliance predicts the price of UWB chips will drop from the current $15 to about $ 4 to $5 , a price point that makes UWB attractive to a wide range of manufacturers, including handset OEMs.
As the market develops, UWB will take two different paths in the kind of products it will be in. One will be for high throughput, with a next-generation solution powering data rates of 1 Gbps or even two to five times that. Those rates will support high definition video and large file transfer. The second path will be low power for use in mobile and battery-powered devices



References: (these are the list of references used in this blog )

1. www.WiMedia.org
   
2. www.uwbforum.org
3. www.wirelessweek.com
4. www.radio-electronics.com
5. www.intel.com/technology/ultrawideband/downloads/ultra-wideband.pdf
6. www.wsdmag.com/Articles/ArticleID/17881/17881.html
   
7. www.in-stat.com
8. www.ABIresearch.com
9. www.ultrawidebandplanet.com
10. Modern Wireless communication by Simon Hykin and Michael Moher (2005 Pearson Education,inc.)
    

6.Current and Future Challenges for UWB Technology

There are challenges to UWB technology from different directions that can threaten its current and future success. These includes:

• design and Regulation challenges
  
• Challenge due to lack of a common standard for everybody
• Competition from other standards

Let us look more closely to these challenges one by one

a. Design and regulation Challenges
The transmitter power level of UWB signals is strictly limited in order for UWB devices to coexist peacefully with other wireless systems. Such strict power limitation poses significant challenges when designing UWB systems. One major challenge is to achieve the performance desired at an adequate transmission range using limited transmitter power. other challenge is to design UWB waveforms that efficiently utilize the band width and power allowed by the FCC spectral mask. Moreover, to ensure that the transmitter power level satisfies the spectral mask, adequate characterization and optimization of transmission techniques ( e.g., adaptive power control, duty cycle optimization) may be required.
Meeting the requirement of the regulation set for UWB by the FCC through design was and is not simple. In the United states, the then-MBOA (now WiMedia) proposal in particular faced strong FCC scurinity. In fact, the group did not receive FCC approval for their technology until March 2005, and the first chips based on the standard were not approved until August 2005. The delay was the result of an FCC requirement that UWB systems undergo strict testing. Though the WiMedia specification hops frequencies in order to minimize interferences, the FCC ordered frequency hopping turned off during testing, thus allowing the FCC to increase its susceptibility to interference . Further, data transmission would need to be turned off. These factors would have made it likely that emissions and interference would appear higher than under actual operating conditions. Although the UWB Forum's proposal was more readily approved by the FCC, UWB's frequency overlap with crucial wireless technologies such as GPS systems and cell phones has caused some concern.
More issues on the design challenges can be found here

b. Lack of a common standard
Even though the WiMedia Alliance was able to get its technology standardized through the European Standardization organization Ecma International as well as the International Organization for standardization (IOS) , the challenge is not yet over. This issue is discussed in section 4. This lack of a common standard is usually referred to as one of the main reasons as to why the UWB technology has not shown enough progress as anticipated in the early 2000's.

c. Competition From Other Standards
UWB also faces competition from other high-speed wireless standards, particularly from the next generation wireless local area network (WLAN) standard 802.11n. The Wi-Fi Alliance is certifying draft 2.0 products before the final 802.11n standard has been ratified by the IEEE. Final ratification is expected in July2008. Nevertheless, users are already enjoying the 100Mbps+ performance promised by this standard. The characteristics of 802.11n standard and the UWB technology is already compared and discussed in section 5.
Though 802.11n is considered the most challenging standard to UWB for the WPAN application, there are other technologies emerging specially in a Wireless Video Home application. Amimon's WHDI and Pulse~Link's CWave are two of the currently emerging wireless technologies and may dominate the vedio distribution marketplace. Both were designed and optimized for video so they are fast, simple, and cheap-something that the consumer electronics market appreciates.
More information on the challenges from Amimon's WHDI and CWave can be found here

How about with Bluetooth?
Despite the likely competition from future and current wireless technologies, UWB could easly be incorporated to work with existing standards. Since Bluetooth and UWB have similar data transfer ranges, concern initially rose over whether UWB would eclipse the technology, particularly since it could perform the same task at dramatically increased speeds. Typically used to wirelessly link computers to peripherals such as keyboards and headsets, Bluetooth operates at approximately 1/100 th of potential UWB speed. Perhaps recognizing the potential downfall of their technology, the group responsible for developing and popularizing Bluetooth decided to link themselves to UWB proponents. Known as the Bluetooth special Interest group, the coalition is now working with the WiMedia Alliance to develop a high-speed version of Bluetooth. This quicker version of Bluetooth uses the WiMedia standard of OFDM to produce speeds up to 480Mb/s over a range of a few meters.

5. Is UWB Best Technology for WPAN?

5.1 Next Generation WPAN Performance Requirement and UWB Technology

Before Discussing about the next generation WPAN performance requirements a few words are in order in order to make clear the difference between WPAN and WLAN standards. These two technologies are separately defined and governed by different technical specifications, standards, and industry alliances. For instance , WPAN standards have been developed by the IEEE 802.15 working group while the WLAN standards have been developed by the IEEE802.11 working group. Typically, WLAN offer greater range while WPANs feature higher throughput and lower power.
WPANs products are currently enjoying good market success, and next generation WPANs solutions(such as Bluetooth's Seattle Release) look to increase data rates in order to handle additional applications such as short range streaming video. New Functionalities and storage capabilities are regularly being added to portable devices, which is driving the need for fast wireless connectivity. The main application today for new WPANs is file transfer , but a more interesting emerging application is streaming video.
Because it requires continues periods of high bandwidth consumption in order to provide a good user experience, streaming video is a unique application. Its maximum throughput requirement ranges from 8Mbps for 320* 240 video resolution to 200Mbps for 2048*1024 video resolution. Compromising on throughput or bandwidth would likely make this application unsuitable.
UWB is the obvious choice to enable these new high-bandwidth applications becouse its key feature is high throughput at short ranges, which is precisely what WPANs require. For this reason, both the Bluetooth SIG and the USB_IF have selected UWB for next-generation WPANs
In order to be used as a Bluetooth Alternate MAC/PHY , WiMedia UWB ( one of the groups discussed in section 4) meets the following requirements( table 5.1):

• Throughput..........................greater than 100Mbps
• Power Consumption..........1mW/Mbps
• Operating frequency..........Above 6GHz

5.2 Which is better for WPAN....IEEE802.11 or UWB?

There are several types of WLANs on the market,and all based on a different type of IEEE 802.11 standards: 802.11a, b, and g are widely deployed today and the draft 2.0 802.11n is currently being fielded. The newer 802.11n has received much press on its promise to enable higher data-rate and longer range wireless networking applications. Indoor ranges for 802.11n are expected to reach up to 70 meters , and outdoor ranges may approach 160 meters. Without doubt this is a clear advancement in WLAN performance in terms of throughput and range.This performance improvement , however , comes with a necessary increase in power consumption and cost because it requires multiple radio chains (Multiple Input Multiple Output MIMO technology).
Because of 802.11's success in WLANs , some are thinking of using the same technology in the next generation of short-range WPAN applications. The WiMedia Alliance ( one of the special interest groups in the UWB Technology) explains why UWB is the best technology for WPAN.
They Compare UWB technology with 802.11n interims of:

• Performance
1. Throughput
2. Power Consumption
• Interference
1. to Bluetooth
2. to Wi-Fi
3. to WiMAX
   
• Cost

a. Performance

1. Throughput: recent testing has shown that, without interferers, 802.11n actually achieves throughputs of 20 to 100Mbps, while 802.11g achieves 25Mbs. WiMedia UWB products today can achieve up to 377Mbps.

2. Power Consumption: This is one of the most important requirements for WPANs because they are intended for use with portable, battery-operated devices. To be successful in the market place,next-generation WPANs must be optimized for low power consumption in order to satisfy consumer expectations. Table below gives the power/Mbps of the different technologies.


As can be seen from the table UWB has low power consumption. This is because UWB systems have been designed for low power consumption from the beginning, taking advantage of the low transmit power allowed by the regulatory rules for this technology.


b. Interference

One of the main applications of next-generation WPAN will be Video streaming, which requires the radios to use large amounts of spectrum, as I already mentioned before. Because of this , next-generation WPANs need to provide some level of spectrum planning in order to avoid interference. If an 802.11 radio is used( instead of an UWB one ) for WPAN, then there are at least three risks of interference caused by the 802.11 radio to other applications in the 2.4 GHz range.This is due to current 802.11 systems considered for WPAN operate in the 2.4GHz range.

1. Interferenceto Bluetooth: In recognition of the risk from WLAN radios, specific mechanisms have been adopted in the latest versions of the Bluetooth specifications to combat interference caused by 802.11 Wi-Fi. Now, a Bluetooth radio can avoid certain channels that are being used by a nearby Wi-Fi radio at specific times. This Technique would be much less efficient, and likely fail, if an 802.11 radio were being used for WPAN video streaming applications ( These streaming application transmit most of the time, which would leave little opportunity for Bluetooth operation.)
2. Interference to Wi-Fi : WI-Fi systems are very successfully used in homes and offices to provide wireless internet access. The bursty nature of the traffic characteristic of internet access allows a large number of users to share the same 2.4 GHz spectrum. Using 802.11 radios for WPANs will cause the 2.4GHz spectrum to be much more crowded, and it is likely to cause serious performance degradation for existing WLANs.
3. Interference to WiMAX: UWB transmitters operating at 3.1GHz or above meet the WiMax required emission ( -70dBm/MHz) , but the 802.11 emission of -41dBm/MHz is much higher than the maximum allowable emission for WiMAX . Obviously UWB transmitters operating above 6GHz exceed that limit by a large amount.

C. Cost
Unit cost for 802.11g is low enough to enable high volume applications.Most manufacturers integrate a majority of the radio components (with exception of power amplifiers) in a single CMOS IC. The same is true for UWB, where multiple companies have demonstrate highly-integrated single-chip CMOS implementations. On the other hand, 802.11n implementations are still expensive and currently ship for four times as much as their 802.11g or UWB counterparts. It is reasonable to expect that the cost of 802.11n will eventually be reduced to 2* that of 802.11g because they include, at minimum, two or more radios.

5.3 Summery and Final Remarks:
The Table below summarizes how the different technologies compare for WPAN applications.







It is clear that 802.11 is optimized for WLAN, because it performs at much higher range than required by WPAN , at higher power, and the cost of 802.11n is too high for WPAN applications. The interface from 802.11 to WIMAX is also a problem when used for stream video.
Observing the current performance of the technologies, the best alternative, may be,is to continue using 802.11 for its intended purpose-WLAN- and use UWB for WPAN. UWB has the distinct advantage of operating at much lower transmit power levels in the 3.1GHz to 10.6GHz ranges, which is well out of the range of WI-Fi, WIMAX, AND Bluetooth 2.0 signals. Implementing UWB technology in WPAN systems avoids all of the interference problems that plague WLAN.

4. The struggle to Adopt Standard for UWB

Road to standardization
Previous battles in technology standards have demonstrated the handful of ways in which a specification can become known as a "standard". First, standard proponents from each side can align themselves with a major standards development organizations, such as the IEEE , and seek official recognition.If the time and cost of sending company representatives to IEEE meetings is a burden, companies could also try their luck by taking products with the standard straight to market.
In some situations, a technology may become a de facto standard in the marketplace. For example, Intel computers running Windows,known as the "Wintel," become a "standard" of sorts after marketplace success.
What is being observed in the process of developing a standard for UWB can show us one way on how a standard can be developed. So i found it interesting to look at what has happened and what is happening to the standardization process of UWB.

The Stagnated IEEE process
A dedicated IEEE task group, known as 802.15.3a or TG3a, has been reviewing proposals for a UWB standard since January 2003. In July 2003, the competition narrowed to two proposals: one from an Intel-backed group( which is now the WiMedia Alliance) and one from a Motorola-backed group (now known as the UWB Forum). For nearly three years, progress toward an IEEE-recognized standard has been virtually deadlocked.
Members continue to vote between only these last two proposals. Except for one occasion, the WiMedia-backed proposal has always earned a majority of votes, with typically 60% of voters in favor of their proposal. However the proposal has never been able to gain the 75% of votes needed of votes needed for the confirmation vote. The UWB Forum's proposal,which received just over 50% of votes on one occasion in July 2004, was also unable to gain the 75% majority to confirm their proposal as the standard.
Members of the TG3a have been frustrated at the endless voting cycle. The WiMedia Alliance has accused the UWB Forum of Hiring a pool of "consultants " in order to pad voting numbers at IEEE meetings. Both sides admit that some task group members may be voting for the proposal supposed by their company, rather than backing the most technologically sound proposal.While this practice may come as little surprise, it is cited as yet another reason why proponents cannot agree to one standard.
Finally, in January 2006 the TG3a group has officially voted to disband.

So, is there any standard for UWB technology today?
After shutting down the IEEE 802.15.3a, both the WiMedia Alliance and UWB Forum have continued to take steps to advance their proposals in the market place.

In seeking an alternative to the IEEE processes, WiMedia Alliance members approached Ecma and requested that they undertake UWB standardization. Ecma agreed and the technical commttee TC20 began working immediately, using the WiMedia specifications as the starting point of the work. Created by WiMedia members from leading PC, CE , mobile device and semiconductor companies, these specifications set the groundwork for enabling short range multimedia file transfers at data rates up to 480Mbps that operate in the UWB spectrum of 3.1 to 10.6 GHz . The Ecma standards were established in December 2005, after which Ecma submitted the standards to ISO/IEC JTC 1 for fast track approval. Finally on March 2007 The WIMedia Alliance announced that the Ecma International standard for ultra-wideband (UWB) technology has been approved for release as an ISO/IEC international Standard.

After being released as an ISO/IEC international standard, the WiMedia Alliance group's UWB technology is gaining much acceptance than the UWB Forum group's . But this does not mean that the WiMedia Alliance group's technology has already won the race. The UWB Forum are also bringing their technologies to market at this time. Even though WiMedia group is gaining momentum at this time, the ultimate winner will be decided by the market.

3. Key Players in UWB

The consumer electronics industry has specifically eyed UWB to potentially provide wireless connectivity between a computer and display, a computer and digital camera ,a television and DVD player, a projector and computer, and numerous other possibilities. Thus , a diverse group of companies have rallied behind the technology.Interest in UWB has sparked the creation of two industry-led interest groups , the WiMedia group and the UWB Forum.
Founded in June 2003 as the MBOA, the WiMedia group has some of the most influential names in consumer electronics. Intel, Sony, Nokia, Sharp, NXP semiconductors, Microsoft, Philips and nearly 150 other companies and organizations hold what is now WiMedia Alliance membership. http://www.wimedia.org

Locked in a decisive battle with the WiMedia Alliance is the UWB Forum, a group founded by Motorolla in late 2004. The group has just over 100 member companies, though unlike the WiMedia Alliance, its members do not include as many prominent consumer electronics companies. Of course, some companies including Motorola has left the group already. www.uwbforum.org

The above both parties use similar frequency bands. But where the two plans differ is in the type of modulation:

• WiMedia Alliance uses frequency hopping (Frequency Hopping Code Division Multiple Access, FH-CDMA) and multiple bands at once. The group's technique splits the UWB- allowable frequency range in to 14 subdivisions, then sends data as "pulses" in a subdivision, switching to other subdivisions as necessary in order to minimize interference and abide by frequency regulations in a particular area. The WiMedia proposal has been touted as the most feasible for international deployment,due to its ability to easily block out spectra that already may be in use in a particular country
• The UWB forum uses DS-CDMS ( Direct-sequence Code Division Multiple Access) so that every one shares the whole space using encryption to keep each signal segregated from its neighbors. That is, each user terminal is assigned a unique spreading signature that makes each user's communication approximately orthogonal to those of others.

A good explanation of the technology being used by each of the above two groups is given in section 2 (UWB technology and application section)

2. UWB Technology and Applications

UWB differs substantially from conventional narrowband radio frequency (RF) and spread spectrum technologies(SS), such as Bluetooth Technology and 802.11a/g. UWB uses an extremely wide band of RF spectrum to transmit more data in a given period of time than the more traditional technologies.

Figure1. Comparison of narrowband (NB) ,Spread spectrum (SS), and Ultra-wideband(UWB)

UWB is a unique and relatively new usage of a recently legalized frequency spectrum. UWB radios can use frequencies from 3.1 GHz to 10.6 GHz - a band more than 7 GHz wide. Each radio channel can have a bandwidth of more than 500MHz , depending on its center frequency. To allow for such a large signal bandwidth, FCC( USA s , Federal Communications Commission) put in place severe broadcast power restrictions. By doing so, UWB devices can make use of an extremely wide frequency band while not emitting enough energy to be noticed by narrower band devices nearby , such as 802.11a/g radios. This sharing of data throughput, but they must be with in close proximity.
Strict power limits mean the radios themselves must be low-power consumers.Because of this low power requirements, it is feasible to develop cost-effective CMOS implementations of UWB radios.With the characteristics of low power, low cost, and very high data rates at limited range, UWB is positioned to address the market for a high-speed WPAN. UWB Technology also allows spectrum reuse due to its short range property.
The advantages of UWB can be summarized as:

• Promising high data rates at very low cost
• Very high spatial capacity
• Extremely difficult to intercept or interfere with
• Best for severe multi-path environments
• Low power consumption and small size
• Sharing the bandwidth with other systems
  
• High precition positioning and radar

2.1 Two Ultra Wideband Technologies
Despite the single name used for ultra wideband (UWB) transmissions, there are two different technologies being developed:

• Carrier free direct sequence ultra wideband technology
• Multi-band OFDM ultra wideband Technology
  

These two technologies are pushed by two different industry groups. These groups are, at this time, trying to bring their technologies to market. But neither could communicate with the other. The detail situation of standardizing UWB technology is presented in the next section (section 3). In order to make things more suitable for this assignment, I will give a brief descriptions of the characteristics of each of the above two technologies.

a. Carrier free direct sequence ultra wideband technology:
This form of ultra-wideband technology transmits a series of impulses. In view of the very short duration of the pulses, the spectrum of the signal occupies a very wide bandwidth.
This technology is known with the following characteristics:

• Based on Direct sequencing technology (discussed next)
  
• Divides the spectrum in to two bands
• Upper band: 6.2- 9.7 GHz
• Lower band: 3.1 - 4.85 GHz
• Omit U-NII band portion which is 5.15-5.35 GHz and 5.75- 5.825GHz
• 6 channels for each band
• Supported data rates is determined by mixture of spreading code length, convolution code rate and modulation scheme
• The Standard calls for BPSK or 4-ary bi-orthogonal keying modulation

The DS-UWB Data Rates











Direct-sequence modulators-process a narrowband signal to spread it over a much wider bandwidth. With this approach , each user terminal is assigned a unique spreading signature that makes each user's communication approximately orthogonal to those of others . This is similar to the way in which distnict carrier frequencies and time slots make users' transmissions approximately orthogonal in FDMA and TDMA , respectively. Spreading the signal de-sensitizes the original narrowband signal to some potential channel degradetions and to interference, this property becomes advantageous as the demand for spectrum reuse increases. The transmitted energy remains the same, but due to the much larger bandwidth, the signal spectrum is often below the noise floor of receivers. the signal looks like noise to any receiver that does not know the signal's structure. This makes the signal difficult to detect, even if one is looking for it.


b. Multi-band OFDM Ultra Wideband Technology:
This form of Ultra wideband technology uses a wide band or multiband orthogonal frequency division multiplex(MBOFDM) signal that is effectively a 500 Mhz wide OFDM signal. This 500Mhz signal is then hopped in frequency to enable it to occupy a sufficient high bandwidth.
This technology is known with the following characteristics:

• It is combination of frequency hopping (discussed next) and OFDM technology
• Spectrum Divided in to 14 groups each 528MHz band
• 4 groups of 3 sub-bands and 1 group of 2 sub-band
• Frequency-domain spreading, time-domain spreading, and forward error coding are used to vary the data rates
• In each OFDM period the transmitted signal hops over 3 different sub-bands of one of the four groups
• Time frequency codes used to vary FH (frequency hopping) pattern
  

The MB-OFDM Data Rates:












Frequency- hopped (FH) modulators - process the narrowband signal and change the carrier frequency every few symbols. A pseudo-random hopping pattern that is known by the receiver is used by the transmitter. To an outside observer, the signal appears to be transmitting on randomly selected frequencies, although the hop time on each frequency is usually constant. Multiple FH transmitters share the same frequency band by using different hopping patterns. If the transmitters are synchronized, then the hopping patterns can be selected so that there are few or no collisions ( both transmitters communicating on the same frequency and at the samre time.)

2.2 Application of UWB Technology:
There is a wide number of applications that UWB technology can be used for. They range from data and voice communications through to radar and tagging. With the growing number of way in which wireless technology can be used, the list is likely to grow.
Although much of the hype about ultra wideband UWB has been associated with commercial applications, the technology is equally suited to military applications. One of the advantages is that with the pulses being spread over a wide spectrum they can be difficult to detect. This makes them ideal for covert communications.

Commercial:

• High speed WPAN/WLAN
  
• Avoidance radar
• Altimeter (aviation)
• Tags for intelligent transport systems
• Intrusion detection
• Geolocation
  

Military:

• Radar
• Covert communications
• Intrusion detection
• Precision geo-location
• data links

Of all the above applications, appliacation of UWB technology for WPAN is gaining much attention. Specially, wireless connectivity for digital home.

Some of the WPAN applications of UWB technology includes:

• Replacing IEEE1394 cables between portable multimedia CE (consumer electronics) devices, such as camcorders, digital cameras, and portable MP3 players, with wireless connectivity
• Enabling high-speed wireless universal serial bus (WUSB) connectivity for PCs and PC peripherals, including printers scanners, and external storage devices
• Replacing cables in next-generation Bluetooth Technology devices, such as 3G cell phones, as well as IP/U PnP-based connectivity for the next generation of IP-based PC/CE/ Mbile devices
• Creating ad-hoc high-bit- rate wireless connectivity for CE,PC and mobile Devices

More explanations about the above applications can be found here