Do you know that we have 1.4 million cellular radio masts deployed worldwide? And these are base stations. And we also have more than five billion of these devices here. These are cellular mobile phones. And with these mobile phones, we transmit more than 600 terabytes of data every month. This is a 6 with 14 zeroes -- a very large number. And wireless communications has become a utility like electricity and water. We use it everyday. We use it in our everyday lives now -- in our private lives, in our business lives. And we even have to be asked sometimes, very kindly, to switch off the mobile phone at events like this for good reasons. And it's this importance why I decided to look into the issues that this technology has, because it's so fundamental to our lives.
Subcarrier-Index Modulation OFDM
Abstract—A new transmission approach, referred to as subcarrier-index modulation (SIM) is proposed to be integrated with the orthogonal frequency division multiplexing (OFDM) systems. More specifically, it relates to adding an additional dimension to the conventional two-dimensional (2-D) amplitude/phase modulation (APM) techniques, i.e. amplitude shift keying (ASK) and quadrature amplitude modulation (QAM). The key idea of SIM is to employ the subcarrier-index to convey information to the receiver. Furthermore, a closed-form analytical bit error ratio (BER) of SIM OFDM in Rayleigh channel is derived. Analytical and simulation results show error probability performance gain of 4 dB over 4-QAM OFDM systems for both coded and uncoded data without power saving policy. Alternatively, power saving policy retains an average gain of 1 dB while using 3 dB less transmit power per OFDM symbol. See: Subcarrier-Index Modulation OFDMRami Abu-alhiga and Harald Haas
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