In ADAMAS project, we propose to investigate the performance of a novel adaptive OFDM P-MP outdoor broadband fixed wireless system for a wide range of service symmetry, attempting to transmit/receive in high bit rates while increasing the operation frequency.

Hence, there is a need to develop modules that could be used in different systems and simultaneously have the capability to adapt the bit rate according to the channel conditions. Consequently, this work targets to develop unified adaptive techniques that could be applied in a variety of applications, maximizing the achievable bit rate (Figure 1b). The adaptation has to be resided both in the physical layer, employing adaptive modulation schemes and in the DLC layer, employing dynamic allocation schemes.

Figure 1: (b). A 3-D plot that depicts the current

status of the applications according to the service

symmetry, frequency and bit-rate.

The main objective of the project is to study, implement and validate a novel adaptive OFDM Point-to-MultiPoint (P-MP) outdoor broadband fixed wireless access system. The adaptivity will reside both in the physical layer, employing adaptive modulation schemes, as well as in the DLC layer employing dynamic allocation schemes in an effort to increase the usable bit rates. In technical terms, the maximisation of the usable bit rate maintaining a given bit error rate at the highest possible frequency is the target of this work. The bit rate will vary from 64 Kbit/s up to 25 Mbit/s with respect to the channel conditions or the traffic requirements.

Two scenarios will be tackled: a licensed and an unlicensed one. The licensed scenario will be frequency located at 10.5 GHz. The other scenario is the unlicensed one in 5.8 GHz frequency band (5.725-5.825 GHz). In both scenarios, the service symmetry will be varied from full broadcasting scenario (where the uplink does not exist at all) up to symmetric scenario (equal uplink and downlink period). Both scenarios will use the DTDMA/TDD in order to obtain the cost reduction and efficient utilisation of frequencies.

Moreover, an objective of this project is to determine the range of frequencies where the OFDM might be not beneficial in terms of complexity and performance when compared to single carrier modulation schemes.

Additionally, within the ADAMAS framework, we plan to address an integrated digital receiver with two-engine architectures (state-space and likelihood-metric engines) that will be optimized from the perspective of the performance/complexity trade-off applying the concept of Per Survivor Processing (PSP).

ADAMAS project will significantly enhance system’s performance in terms of:

• Bit rate achieved
• Spectrum efficiency (in bits/sec/Hz)
• Robustness
• Geographical coverage

The ADAMAS project will develop technology for a Fixed Broadband Wireless system using Time Division Duplex to support Wireless Terminals in both licensed and unlicensed environments. This system will use only one frequency band per Wireless Access Point and make efficient use of the frequency spectrum available. The ADAMAS system will provide Point-to-MultiPoint multimedia broadband applications to Wireless Terminals at a presumed lower price than current systems, providing similar services.

Thus, the developments within ADAMAS will allow customers to gain access to broadband telecommunications and data communications services, delivered to their premises by radio. These systems are intended to be able to compete with or complement in other cases, broadband wired access systems including xDSL and cable modems. Due to the consortium’s structure, strength and experience in the specific area of P-MP technologies, a major push towards the introduction of new technologies into residential and small-to-medium sized enterprises environment is expected, which would make one of the most important results of the project. Contributions in ETSI/BRAN HIPERACCESS standardisation body will be submitted, helping on the one hand to the definition of the reference model, and on the other providing the synergy for the wide deployment of broadband fixed wireless access systems.