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Content archived on 2024-05-24

Wireless Indoor Flexible High Bitrate Modem Architecture


To satisfy increasing demand on broadband wireless services and ubiquitous network access, it is critical that the technologies be available to support flexible high bit-rate communication in slowly mobile indoor environments. The present day state of the art is aimed toward cellular telephony or customised systems in high bit-rates. The current flexibility research is towards software radios that are too far in the future to have major impact within time-to-market limits. This project aim to flexible, multi-technologies platform, before trying to reach the full software radio paradigm. The major technology thrusts are in the areas of RF/IF processing (5/17 GHz), baseband algorithms, MAC/LLC methods and computing architectures for flexible, high speed (64 kbit/s - 100 Mbit/s) modems.

The objective of the proposed research is to suggest a high bit-rate flexible and configurable modem architecture, which works in single-hop, ad hoc networks and provides a wireless access to the Internet in an indoor environment where slow mobility is required. The main emphasis will be in the OSI layers 1 and 2. The best possible performance with a reasonable complexity is attained by using a jointly optimised adaptive system which includes the multiple access method, diversity, modulation and coding, and equalisation and decoding. The system is not optimised in advance but it will be adaptive and configurable in the run time. This is a step towards a software radio, which is presently too far in the future due to technological problems. Bit rates from 64 kbit/s up to 100 Mbit/s are considered at the frequency in the band of 17 GHz - 19 GHz even though 5 GHz will be also analysed. The bit rate is variable depending on the user needs and channel conditions. Flexibility is attained by using a multi-carrier modulation method even though single-carrier methods will be also considered. Best possible methods are used including joint diversity, modulation and coding (such as space-time coding) in the transmitter and joint equalisation, decoding and channel estimation (such as per-survivor processing) in the receiver. The architecture will be analysed, simulated and demonstrated. The main deliverables include detailed reports on the system architecture and its performance, scientific publications and the demonstrator. The driving force is research, not the existing standards. The research reports will be a good basis for defining new standards.

Work description:
The work is done in high quality research groups who are using compatible simulation tools so that almost full (off-line) simulation is possible. The project consists of three co-operating teams concentrating on RF/IF, baseband and Network and Terminal Connectivity. Before actual research work borderlines of work are defined together. Finally, after main research activities the feasibility of operation of developed solutions is measured and analysed together. In parallel with actual research work, continuous assessment and evaluation of results is done and dissemination, use and technology implementation plans are generated. During research activities best possible methods are searched for core parts of the modem. Then, the architecture will be analysed, simulated and demonstrated.

WIND-FLEX concentrate on following issues:

Research on critical parts and issues related into digital algorithms, protocols and RF/IF parts of adaptive modems. Currently OFDM seems to be the most promising system model. Also usability of PSP-principle in different parts is investigated. Results are published as official deliverables and Scientific publications. Standardisation organisations (ETSI, IEEE) are informed about new results.

Simulation models about critical algorithms and protocols.

Accurate estimates about the complexity of different approaches enabling adaptive operation.

Implementing demonstrator with following features:

It includes two macro prototypes of designed modems:
RF/IF solutions will be based on laboratory equipment, i.e. the aim is to show that baseband technology can be attached to RF/IF chain;
SW implementation is preferred in the implementation of baseband algorithms.

However, custom hardware may be needed in interfacing and implementation of the most complex algorithms.

The most of DLC/MAC software is executed on powerful PC or workstation. The DLC/MAC only shows (like RF/IF) that full end-to-end bit-transmission is indeed possible with the demonstration system.

Demonstrator enables point-to-point demo.

Demonstrator will be based on existing HW and SW implementations as much and possible. The maximum speed requirement (100 Mbit/s) is considered in all algorithm, protocol and implementation architecture research and design. The maximum speed of the final demonstrator will depend on the availability and price of needed technology and effort needed to utilise it. The estimate of the bit ate of the demonstrator will be defined in the second project year.

On general terms the project is promoting the objectives of IST 5th framework (Key Action IV) by promoting the excellence in the technology crucial to the Information Society, supporting information transformation from leading edge research to industry and further to citizens of the EC and supporting in the forming user-friendly information society by advising our organisations and governmental bodies in the information society issues, where our advice is based on hard technological and scientific facts. More specifically WIND-FLEX is contributing to social objectives by building the technological long-term basis for European Research and Development, executing multinational, multicultural project that is doing real research contribution, building basis technologies for wireless (Internet) access that is usable for all citizens and building bridges between European research groups and citizens.
The two main project results are, first, the very high bit rate 17 GHz FAR PHY (HW) demonstrator and the corresponding VHDL simulation environment for the complete system and, secondly, the MAC/DLC (SW) demonstrator. The FAR is an abbreviation for Flexibility/Adaptability/Reconfigurability. The novel FAR framework makes WIND-FLEX as an environment-aware, autonomously acting radio. The short descriptions of the demonstrators (and VHDL simulation environment) are as follows. To proof the system concept, the FAR PHY demonstrator implements a very high bit rate, up to 160 Mbit/s, 17 GHz two-directional link. Real-time adaptivity from the novel FAR concept is implemented in the demonstator by maximizing adaptively bit rate of the system according to channel condition. After bit rate adaptation, power control is also utilized to minimize the transmission power. Then, real-time reconfigurability is demonstrated by being able to "switch" turbo code and WSCE (Weak Sub-Carrier Excision) on and off. The idea of this procedure is to minimise the use of processing power which is much larger than the transmission power.

Furthermore, the complete system for VHDL simulation including Master and Slave devices with a perfect, delay-only channel was integrated successfully. The implementation performance of the system can be verified by VHDL simulations. The MAC/DLC demonstrator set-up includes two generic PC laptops, with a Linux operating system. The MAC/DLC functionalities have been integrated into the Linux kernel and data communication is performed through Logic-TDMA emulation via Ethernet. The MAC/DLC kernel module is a virtual device driver for the operating system and creates a virtual network interface for data communication via existing hardware. In this demonstration the performance of the most critical parts such as scheduling and information data exchange of the WIND-FLEX MAC and DLC can be tested. Concerning IPR & Dissemination including research dimension forming the theoretical basis for the new innovative system concepts (e.g. the FAR concept), the following achievements are reported:
- 5 journal papers
- 60 conference papers
- 1 Doctoral Theses
- 5 filed patents
- 3 public HW demonstrations.

Call for proposal

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EU contribution
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Participants (8)