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GENERAL OBJECTIVES


The general objective of EMPhAtiC is to propose an innovative technological solution allowing increased data throughputs for Public Safety radio-communication systems, in order to satisfy emerging new data service needs in cohabitation with existing networks in the same frequency bands, to facilitate a smooth migration towards broadband systems and to increase spectrum efficiency.

In the PMR/PPDR context, both cell-based and ad-hoc broadband data networking solutions are needed and will be addressed in EMPhAtiC. The coexistence issues and radio environment are similar in both cases. Ad-hoc methods studied for future releases of LTE are potential solutions, but they have to be adapted to the difficult radio environment of the PPDR cohabitation scenario. In addition to the mentioned PMR/PPDR case, the advanced waveforms and signal processing techniques to be developed and validated find applications in various other scenarios of flexible spectrum usage and cognitive radio.

 

Figure on: Higher data rates for Public Safety Evolution


At the waveform level, the main issue is the poor spectral containment of the CP-OFDM subcarriers, leading to high side lobes of the modulated OFDM spectrum, which creates interference to neighbouring frequencies and is thus problematic in the coexistence scenario to be addressed. Additionally, high flexibility is needed to utilize effectively the variable spectral gaps between different narrowband users. Furthermore, the radio implementations have to support non-contiguous spectrum allocations, at least on the base-station side. Multicarrier modulation is a natural approach to address the latter issues, but increased flexibility is of significant interest, e.g., in the form different subcarrier spacings for different users. New concepts on multimodal, multi-access flexible spectrum (DSA Dynamic Spectrum allocation) require new functionalities:

    • fast accurate spectrum analysis
    • reliable channel state information
    • high flexibility/variability and scalability
    • Coexistence with narrow bands
    • quality of service
  • a PHY layer able to support these functionalities is needed
  • FB-MC (Filterbank Based multicarrier)/enhanced OFDM scheme can support DSA and CR better than OFDM.
  • The best and innovative techniques and algorithms available must be picked up, integrated and demonstrated

EMPhAtiC project will evaluate the applicability of the considered waveforms in heterogeneous networks, including cell-based, ad-hoc, cooperative and relaying networks, having in mind the coexistence with legacy waveforms in the PMR band. The project will also develop efficient solutions for the needed flexible multimode transmitter and receiver signal processing functions, considering also channel estimation and equalization and synchronization functions.


MAIN OBJECTIVES ARE:

  • To develop an efficient and highly flexible/variable filter-bank processing structure. Such filterbanks could accommodate simultaneously different modulation formats with adjustable centre frequencies and bandwidths, possibly with non-equidistant subchannel spacings, and they could be used for the modulation, demodulation and frequency-domain equalization of different FB-MC and FB-SC waveforms, even simultaneously. Regarding the coexistence between narrow-band and broad-band PMR systems, such a flexible filterbank could also provide in an efficient way the functionality of transmitter and receiver channelization for legacy PMR signals
  • Develop the needed channel estimation, equalization and synchronization functions, which are compatible with the multimode waveform processing solution. An efficient unified synchronization and channel equalization concept will be established for different transmission modes in the context of multimode non-uniform filterbanks (FB-MC).
  • Improve the efficiency through the exploitation of multiple antennas. The objective will be to propose efficient transmission schemes, develop detection and channel estimation algorithms based on uniform and non-uniform multimode FB-MC MIMO signals such as STBC-coded, SFBC-coded and SM-multiplexed.

 

  • Feasibility and performance of FB-MC techniques in specific environments, e.g., relays, multi-hop and cooperative environments, with some loss of synchronization: The objective will be to study the advantages of FB-MC when used in cooperative MIMO schemes and optimize the synchronization and channel estimation aspects of such a scheme. This performance can then be compared with the CP-OFDM based scheme, in fully and partially synchronized scenarios. Another objective is to improve schemes that do not employ FB-MC, such as coordinated multi-point, beamforming, two-way relaying etc., and compare the performance with FB-MC based schemes.

 

  • Radio sense analysis for flexible spectrum usage. The multimode non-uniform FB-MC will introduce flexibility in cognitive radio systems facilitating also spectrum sensing in heterogeneous radio environments. Feature based algorithms will, spatially and temporally, sense the spectrum occupancy of the used wide frequency band allowing flexible spectrum use for mobile broadband applications.

  • The proof of concept will be achieved through use of software simulation platform and the hardware platform for experimental performance evaluation.
 

EMPhATIC Project is a Small and Medium-scale focused Research Project (STREP) supported by the 7th Framework Programme.

Contract number: 318362
Project duration: 01/09/2012 – 01/03/2015 (30 months)