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3GPP-LTE-like transmission has been demonstrated wirelessly over the air with real-time transmission and non-real-time receiver post processing on IMEC’s prototype of its FLAI platform. The system makes use of novel terminal synchronization and analog front-end compensation (crystal frequency offset, IQ imbalance, phase noise) techniques to achieve a high spectral efficiency. IMEC has patented a technique to acquire the carrier frequency offset (CFO) in the presence of IQ imbalance, based on a designed preamble.



The accuracy of the CFO estimation is high, achieving a few hundreds Hertz for a typical IQ imbalance. This technique enables demodulation of a 64QAM constellation at the receiver and therefore realizes the high data rate promises of the 3GPP LTE air interface in practice. In the demonstration, the received constellation (after channel equalization) is compared to the original one. By activating and deactivating the front-end compensation mechanisms, it is possible to evaluate their effects.



IMEC also developed a transaction-level model of the complete transmit/receive SDR platform, to support a wide range of standards including 3GPP-LTE, 802.11n, 802.16e and DVB-H. Besides a baseband processor, it includes an ARM processor, a digital front-end core, a forward-error-coding unit and a direct memory access engine for accelerating data transfers. The model allows verifying the complex data movement and synchronization between different blocks of the architecture.



These results were obtained within IMEC’s M4 program in which IMEC is building a heterogeneous multi-processor system-on-chip platform enabling flexible implementation of most wireless communication standards at low power. Such a solution is desired by the industry to enable seamless connectivity with first generations of SDR-based mobile terminals and handhelds operating at limited battery energy. The functionality support spans from cellular (CDMA) to high data rate WLAN-WiMAX-DVB (OFDM-MIMO) standards.



http://www.imec.be/wwwinter/mediacenter/en/3GPPLTE_2006.shtml