Transparent wireless transmission over the ACCORDANCE optical/wireless segment
Following the evaluation of FP7 proposals under the Call 4 objective, the network of the future, the STREP project ACCORDANCE has been funded to develop a converged copper/optical/radio OFDMA-based access network with high capacity and flexibility. The ACCORDANCE topology supports the integration of technologies and the interoperability of protocols in the form of distinctive network segments, e.g. legacy xPONs, xDSL, legacy wireless etc., through the application of OFDM(A) to provide segment access to and from the network central office. In particular, ACCORDANCE introduces the integration of dominant wired and wireless technologies in a hybrid network segment for greater flexibility and mobility at ease of last-mile implementation. To that extent, a converged passive optical network architecture supporting standard WiMAX/LTE signal formats by means of FDM subcarrier transmission downstream to remote ONU/BSs has been in the focus of this paper. Transparent operation for five FDM subcarriers carrying 3.5 GHz WiMAX channels has been demonstrated with measured EVMs of -31 dB obtained at selected ONU/BS antenna inputs for all subcarriers spacing. In addition, external versus direct modulation evaluation measurements exhibited superior SFDR figures for the former compared to the latter allowing for increased number of subcarriers in a FDM window and consequently network scalability.