By Timothy Sanders

Background

Runcom Technologies Ltd., may not be well known to broadband wireless service providers. It is after all a silicon vendor that supplies original equipment manufacturer (OEM) radio vendors. However, the technology it has developed called Orthogonal Frequency Division Multiple Access (OFDMA®) is at the core of the next major WiMAX standard to be defined---the 802.16e Mobile WiMAX standard. With the recent acquisition of Flarion by Qualcomm OFDMA® is much in the news.

We decided to have a conversation with Israel Koffman, Msc., vice president of Marketing for Runcom to learn a bit about this technology and why it is so vital to the WiMAX platform. But first a little background on the company and how things work.

Runcom was founded in 1997 by a group of engineers led by Dr. Zion Hadad. Dr. Hadad already possessed a stellar career with stops at InnoWave (acquired by Alvarion) and InterDigital. Himself a veteran technology professional,  Israel Koffman formerly served as chief technology officer of Gilat Communications, Ltd., and president of Orbit Communications. As he explained Runcom's earliest roots began in an unlikely place.

"Interestingly, the company did some CDMA work during the early days for several satellite projects," Koffman said.

However, believing a better future lay elsewhere it garnered its first standards win in 2001 when its OFDMA® technology was incorporated as the core component of the European ETSI television broadcasting standard DVB-RCT. In fact, the firm holds 30  International patent applications for its technology.

Today the company operates in two distinct modes. One is heavily involved in engaging in efforts to incorporate its technology into important standards. The other mode focuses on silicon solutions for PHY and MAC ASICS chips for user terminals and base stations. It sells solutions to equipment vendors. However it is not an OEM itself. Mr. Koffman explains more about this below. So how does the technology work?

Basically, OFDMA® divides signals into many subchannels of hundreds or even thousands. This facilitates vendor solutions that dedicate many channels spread across the plethora of available sub channels to one user. This obviates multi-path interference and in fact actually utilizes multi-path signal both in phase and out of phase to synergize an overall stronger signal.

This set of sub channels changes dynamically every several symbols. Additionally the quantity of channels, the modulation and the power or gain of each can be altered on the fly based on the user's distance from the base station.

For users close in the number of channels can be expanded and coupled with modulations such as 64 quadrature amplitude modulation (64 QAM) to deliver high throughput levels. When users are farther away the system dynamically reduces the number of channels and the modulation rate (QPSK for example) in order to elevate the gain of each and punch signal to the customer.

This enhances NLOS and according to Runcom virtually eliminates cell size shrinkage under heavy loads. The technology is exciting and clearly focused on coping with high demand mobile service delivery. What follows are some questions that Mr. Kaufman responded to that hopefully shed more light on why this technology is poised to support the core of Mobile WiMAX.

Tim Sanders: Runcom is widely recognized as the inventor of Orthogonal Frequency Division Multiple Access (OFDMA®)---What perceived need in the marketplace led your firm to this innovation?

Israel Koffman: The market that was perceived by Runcom for OFDMA® was the Beyond 3G market and the Interactive TV Market (Terrestrial and Satellite). Today we see some more applications such as Home Land Security markets and Mobile Surveillance.

Tim Sanders: Do you characterize your company as more of a silicon chip vendor or board vendor---Your customers are really OEM's aren't they?

Israel Koffman: We characterize our company as a silicon vendor for both the User terminal and the Base Station equipment vendors. Runcom supplies silicon solutions and reference designs to OEM's , ODM's, and Equipment vendors, Nowadays as the market is in its infancy period, we also supply 802.16e  evaluation systems directly to Operators worldwide that are willing to learn, test and evaluate the OFDMA® technology performance.

Tim Sanders: When did Runcom debut its OFDMA® technology?

Israel Koffman: Up until now we have done numerous field trials of the OFDMA® technology. The substantial debut of a first 802.16e deployment (WiBro profile) will be at the APEC Conference in Busan, Korea in November 2006.

Tim Sanders: Will OFDMA® lead to a superior mobile product versus 802.16-2004 (fixed WiMAX---if so, in what ways beyond mobility itself?

Israel Koffman: First , I want to correct one misconception, the 802.16-2004 standard includes an OFDMA® mode ( with 2K FFT) along with the OFDM solution with 256 FFT ( that was adopted by Wimax as the profile of choice for fixed applications). Now to your question, OFDMA® offers substantial advantages for fixed applications beyond mobility itself such as; bigger cells due to the processing gain, better multipath protection due to bigger FFT sizes especially in urban and Non Line of  Site (NLOS) environments, improved granularity for data and increased user capacity. All of those attributes leads to lower deployment and operating costs. In addition, one of the biggest advantages of the OFDMA® solution is the subscriber and infrastructure equipment cost, that due to improved economies of scale, will be much lower.

Tim Sanders: Do you anticipate that OFDMA® may eventually be used in the 802.16-2004 standard, which currently seems likely to be incompatible with 802.16e?

Israel Koffman: Yes , we anticipate OFDMA® to be used in both 802.16e as well as in 802.16-2004 ( Mobile and fixed applications). Regarding the compatibility issue, the 2K FFT OFDMA® mode is compatible with both standards.

Tim Sanders: Does OFDMA® prevent the shrink of cell ranges under load that code division multiple access (CDMA) sometimes suffers from---resulting in lost calls?

Israel Koffman: There is no degradation of Cell performance under load compared to CDMA, as OFDMA® can adaptively allocate the cell capacity to all the subscribers in the cell without deteriorating the cell capacity or losing calls.

Tim Sanders: In Runcom's view will 802.16e always be only a licensed spectrum band technology or is it possible that license-free bands (particularly in the US) may have product designed for them (i.e. 5.8 GHz).

Israel Koffman: Runcom's view is that OFDMA® can be used in licensed as well as licensed-free spectrum due to the inherent robustness of OFDMA® in noisy spectral environments.

Tim Sanders: Are there any special challenges to using this technology in lower frequency spectrum such as 700 MHz or 900 MHz---could it increase the spectral efficiency in these bands?

Israel Koffman:  There is no special challenges for OFDMA® in working in the UHF band, Runcom already has  a commercial OFDMA® solution based on the DVB-RCT standard that working in this band ( 470 to 860MHz) using 6,7 or 8MHz channels and achieving a spectral efficiency of 3 to 4 Bits per second per Hz at 64QAM. Equivalent efficiency can be achieved with the 802.16e OFDMA® solution.

Tim Sanders: Does OFDMA®, as used in 802.16e, improve non-line-of-sight penetration relative to 802.16-2004 standards?

Israel Koffman: The OFDMA® used in 802.16e can improve NLOS performance relative to 802.16-2004 OFDM due to the larger FFTs sizes ( 2K,1K and 512, compared to 256)  that improve the performance in multipath environments. And due to the technology's  ability to achieve a higher power spectral density by concentrating the energy in fewer subchannels.

Tim Sanders: Who are some of your larger customers?
Israel Koffman:  Runcom has large customers in Korea, Japan, Europe and the US. However due to NDA agreements we cannot publish them yet.

Tim Sanders: What is most gratifying about having your technology likely become the one chosen to support 802.16e----and is it a fait accompli at this point?

Israel Koffman: The most gratifying portion at this point of time is the consensus and acceptance achieved among the market leaders that OFDMA® is the technology of choice for BWA applications due to its technical superiority; now the challenge is how to convert this consensus into a mass-market worldwide deployment.

Tim Sanders: The public seems a bit confused about the difference in various OFDM Mobile approaches. How is Runcom's OFDMA® version of OFDM different from say a company like Flarion which has built an iteration called Flash OFDM---in a general sense?

Israel Koffman: Not much technical information was published about the Flarion solution, however the main difference is that Runcom's OFDMA® solution is Standards based whereas Flarion's solution ( now Qualcomm) is proprietary.

Tim Sanders: Does OFDMA® relay on an TDMA approach?

Israel Koffman: Yes, OFDMA® is a combination of  FDMA and TDMA.

Tim Sanders: Does Runcom's technology pre-date the Flarion product lines?

Israel Koffman: I don't want to enter into IPR issues.

Tim Sanders: In terms of the integration of OFDMA® into Mobile Wi-MAX, how does Runcom anticipate variations in vendor approaches to presage changes or growth in the OFDMA® approach?

Israel Koffman:  There is still a lot of room for differentiation between vendors using  OFDMA® Mobile WiMAX. Among them are: PHY /MAC Implementation, smart antennas, spectrum usage (Frequency reuse, single frequency networks, etc,) ; Higher layer differentiation (QoS, Applications, Management etc,).

"OFDMA®" is a registered trademark of Runcom Technologies, Ltd.

Israel Koffman - VP Marketing

Mr. Koffman has more than 20 years of managerial experience in leading positions in the high-tech industry. Prior to Runcom Mr. Koffman was the Chief Technology Officer of Gilat Communications Ltd. Prior to Gilat, Mr. Koffman spent 18 years at Orbit-Alchut technologies Ltd., first as R&D engineer, then at various senior positions in R&D and marketing, and finally as President of Orbit Communication, Ltd., a subsidiary of Orbit Alchut.  In addition Mr. Koffman was one of the founders and the active Chairman of the ISIS Consortium for the development of advanced satellite communication terminals. Mr Koffman holds an MSc. Degree in Electrical Engineering (EE) from Drexel University in Philadelphia US.

Tim Sanders is founder of TheFinalMile, Inc., a fixed wireless consulting group. His experience came from running a multistate Wireless ISP. He can be reached at tim@thefinalmile.net  or 828-253-0702.