Site:                Ericsson Radio Systems AB
                      Torshamnsgatan 21-23
                      164 80 Stockholm
                      Sweden

Date Visited:  26 April 1999

WTEC Attendees: N. Moayeri (report author), A. Ephremides, M. Iskander, R. Rao, W. Stark, J. Winters, L. Young

Hosts:            Soren Anderson, Manager, Antenna Systems and Propagation Research, Ericsson Research, Corporate Unit
                     Hakan Eriksson, Vice President and Gen. Manager, Ericsson Research, Corporate Unit
                     Hakan Eriksson, Manager, Radio Access Research, Terminals
                     Ulf Forssen, Director, System and Technology, Business & Product Line Management TDMA Systems
                     Bjorn Gudmundson, Research Director, Radio Systems
                     Bo Hedberg, Senior Expert, Radio Technology Research
                     Johan Skold, Expert, Digital Radio Access in Cellular Systems, Radio Access and Antenna Systems Research
                     Anders Khullar, Ericsson, Lund

BACKGROUND

The panel visited the Radio Systems division of Ericsson, where most of the R&D work related to wireless communications is carried out. Ericsson, however, is much more than this and is active in many other areas of electrical engineering and information technology. The most important and active area of wireless communications from a commercial point of view, as the 21st century approaches, is the development of 3G wireless communication systems. The International Telecommunication Union (ITU) is vigorously pursuing the development of the International Mobile Telecommunication 2000 (IMT-2000) standard for 3G wireless systems, which it intended to complete by the end of 1999.

Ericsson is a powerful voice and a major player within the European Telecommunication Standards Institute (ETSI), which is the sponsor of the W-CDMA proposal for the IMT-2000 standard. Ericsson has had the largest share and contribution in the development of Bluetooth, which is a short radio for wireless LAN type applications in the 2.4 GHz ISM band. To be more precise, Bluetooth is a cable replacement device that connects all personal computing and communications devices to each other in a wireless fashion. In fact, it is to be used even in future home appliances if all goes well with its development by Ericsson, IBM, Intel, Nokia, and Toshiba.

The first presentation was given by Hakan Eriksson, Vice President and General Manager of Ericsson Research, about the areas Ericsson is involved with and some facts about research in areas of high technology in Sweden. He said that universities are now more involved in industrial research in Sweden. They work closely with Ericsson. He then talked about the distinctions between 3G and 4G wireless systems. In case of 3G wireless, the spectrum had been clearly specified from the outset. It is much harder to define 4G wireless, because the spectrum has not been defined. He showed a slide of different wireless systems on a bit rate vs. mobility (fixed, local area, wide area) plane. He talked about three scenarios for voice-over IP.

The first scenario is what we have today. He also compared several scenarios (cases of sending various types of data) in traditional ways and over a wireless network. He showed that wireless made more sense than the traditional ways in a number of cases, i.e., it was cheaper, at least with the present pricing structure we have today. He also showed that for email, wireless is a lot better, but for images and video, traditional ways are still better. He stated that it would be very unlikely that people would watch video on a small pocket-sized terminal. However, such terminals would be good for voice, email, postcards, and music.

Bjorn Gudmundson explained that research at Ericsson has a shorter horizon than the 10 years that WTEC study team member Tony Ephremides mentioned in his talk. Gudmundson added that the Ericsson staff present at the meeting all worked on radio aspects, and that they would not be the best people to answer network-related questions such as whether ATM or IP was the best alternative for sending voice and some other types of data over the network. There are some experts in those areas at Ericsson, but they were not present at the meeting. Regarding ACTS, FRAMES, and other such programs administered by the EC, Gudmundson said that he believed that those programs were not very efficient, as there is a lot of paperwork and overhead. On the positive side, these programs represent a framework for industry to work closer with universities all over Europe. But then Ericsson has had good informal relationships with the universities for many years.

Bo Hedberg gave a talk on multi-standard, multi-carrier, wideband radios. Multi-carrier radios have to handle much larger dynamic ranges. That means stricter requirements on the A/D, D/A, and the multi-carrier power amplifier (MCPA). Some part of their architecture can be controlled digitally and through software. The RF front-end generally is not controllable. He said that power efficiency was important not just at the mobiles but also at the base stations. Otherwise, they would have to use large fans to keep the MCPAs cool, and that would increase the price quite a bit. The dynamic range in multi-standard, multi-carrier, wideband radios would increase by about 20 dB over present systems (GSM). Half the cost of future base stations will be in the MCPA. The present price for this component is about $100 per watt of average RF output power.

Hedberg felt that a lot of research was needed during the next several years to improve the MCPAs. He concentrated on the base station, because he thought the problem was harder for the terminal stations. He felt that the software radio solution was very costly for terminals. The technology needs to mature before it can be used at terminals. Note that the multi-carrier requirements at the terminals are much looser than in the base stations. The 1 microsecond frequency-hopping rate discussed refers to the radio at the base station. It is not possible to have such a high rate at the terminals. The present rate used at base stations, based on analog synthesizer techniques, is one frequency hop per millisecond.

Soren Anderson gave a talk entitled, "Adaptive Antennas in Wireless Systems." He outlined possible alternatives for smart antennas and space-time processing. He presented a general radio architecture for taking advantage of these concepts. As always, the interesting question is how much benefit would one get for the cost? In cellular systems, the downlink is usually the bottleneck due to interference. So, when it comes to smart antennas and space-time processing, it is best to concentrate on the downlink. In an FDD system, for example, one knows a lot more about the characteristics of fading in the uplink direction than in the downlink direction. In a TDD system, one has a different situation.

Anderson then talked about the potential benefits of smart antennas in GSM downlink transmission. He showed a 5-6 dB improvement at the mobiles. Yet another example shows that with sector antennas the quality drops very quickly in comparison with smart antennas. The measure of quality was probability of frame error rate being less than 2%. Note that power control is independent of what was discussed here. PC has its own gains. Also note that to get the maximum benefit of smart antennas in a heterogeneous network, one needs to have good estimates of the traffic distribution in the cell.

Bjorn Gudmundson talked about radio access technologies. He said that mobile Internet access will be the main driver for wireless systems in the future. As far as fourth generation (4G) wireless is concerned, it is not clear whether it should provide much better coverage-bitrate performance or somehow combine in an architecturally sound fashion a variety of systems such as LMDS, Bluetooth, WLAN, IMT-2000, mobile satellite systems, etc. He then concentrated on the evolution of cellular systems by showing 2G, 2.5G, and 3G systems. He put the EDGE system in the 3G category. He talked about the structure of dedicated physical channels in W-CDMA. He said that it was harder to use smart antennas in IS-95, because it handled the pilot bits differently than in W-CDMA. He then compared GSM and EDGE. In GSM the modulation is GMSK, which transmits one bit per symbol. EDGE uses 8 PSK. The concept of adaptive coding and modulation helps EDGE adapt itself to the link quality. He went over major differences between W-CDMA and CDMA2000. He then talked about certain indoor systems (WLAN, Hiperlan-II, and Bluetooth). The distinction between Bluetooth and Home RF was questioned. Gudmundson did not have any comments about Home RF.

Ulf Forssen talked about EDGE and how it related to GSM and W-CDMA. It is, of course, an extension of GSM. He discussed the relationships between EDGE, GSM, and TDMA/IS-136, as well as the tradeoff between spectrum efficiency and average throughputs. In summary, EDGE offers a way to harmonize GSM and IS-136. It has been approved by ETSI and UWCC and has been submitted to ITU. It will provide global roaming for a very large user base.

Johan Skold talked about W-CDMA. He went over a number of features of the UTRA system.

Hakan Eriksson, Manager of Radio Access Research, gave a presentation on mobile terminals. He talked about their present terminals and future directions. He also talked about some possible applications. In addition, he talked about Bluetooth and the Wireless Application Platform (WAP) Forum. Symbian (Ericsson, Nokia, Motorola, and Psion), which is an open architecture, allowing different software developers to develop new applications for these terminals, was also discussed.

Anders Khullar's talk was titled "GSM Terminal Evolution." He discussed positioning systems and their impact on mobile price. He covered TOA, OTD, and GPS. He is with Ericsson, Lund.


Published: July 2000; WTEC Hyper-Librarian