Iterative decoding techniques for ring-type magnitude modulated signals

Ring-type Magnitude Modulation for LINC: a pragmatic approach to the efficiency challenge

“…TRANSCEIVER SCHEME Leveraging on LINC concept and the new RMM technique proposed in the previous section for OQPSK bandlimited signals, this section presents a new power-efficient OQPSK RMM-LINC transceiver scheme, foreseen as an enabling component of multi-layer massive MIMO transmitter schemes for high-order constellations recently proposed [15], [16]. Since the RMM adjustment of each symbol increase the system's noise sensitivity, it is studied the impact of the RMM technique on the transceiver's BER performance, and it is also proposed an iterative receiver scheme [21] designed to reduce the distortion introduced by the RMM method.…”

“…Accordingly, an iterative decoding scheme has been recently proposed [21], which is depicted in Fig. 8, consisting in an initial estimation of the received symbol's RMM coefficients and using that information to iteratively improve the receiver's decision process.…”

“…However, the deployment of mm-wave systems faces important challenges regarding the channel propagation constraints (this is characterized by high free space path losses, small diffraction effects, and huge losses due to obstacles) and implementation difficulties at the hardware level. These issues combined with the large bit rates means that 5G's power requirements are much more severe than with conventional This work was partially published in IEEE GLOBECOM'2015 [19], IEEE VTC'2016-Spring [20] and IEEE ICC'2016 [21], and it was funded by FCT/MEC through national funds and when applicable co-funded by FEDER-PT2020 partnership agreement under the project UID/EEA/50008/2013.…”

“…However, when applied to bandlimited OQPSK signals, conventional magnitude modulation (MM) techniques only control the maximum upper envelope excursion, with the resulting signals still having a high dynamic range (although with lower PAPR), with frequent zero crossings, not allowing an efficient LINC transmission. This paper develops the recent proposed ring-type magnitude modulation (RMM) method [19]- [21], especially designed for narrowband OQPSK signals, to be included in a singlecarrier (SC) transmitter with a LINC power amplification stage (which for simplicity will be referred to hereafter as a LINC transmitter). Unlike conventional MM techniques, the RMM technique leads to OQPSK signals with compact spectrum and whose envelope has a low dynamic range and very low PAPR, leveraging an efficient power amplification.…”

“…After explaining its main features and the algorithm for computing the RMM coefficients, section IV presents the proposed transceiver scheme that combines RMM with the LINC technique, where it is explained the procedure to choose the RMM amplitude boundaries that address the LINC's challenges. In this section it is also presented an iterative decoding scheme that makes up for the distortion introduced by the RMM coefficients [21]. Section V explores the possible power efficiency and bandwidth tradeoffs that result from either using post-filtering clipping together with passive combiners or by employing a Chireix combiner instead.…”