An efficient technique for out-of-band power reduction for the eliminated CP-STC-shaped system for 5G requirements

Abstract

The most dominant needs for the recent wireless mobile applications are higher bandwidth (BW) efficiency, higher energy efficiency higher quality of services (QOS). The main technique in 4G systems is OFDM but it suffers from some limitations such as large peak to average power ratio (PAPR), higher Out-of-Band (OOB) power radiation, and wasting bandwidth efficiency due to cyclic prefix (CP) extension. In his paper, these OFDM limitations will be reduced with low computational complexity compared to filter bank multicarriers (FBMC). The proposed scheme is based on symbol time compression (STC) for OFDM system. The proposed STC-Shaped system is achieved via interleaver-spreader and symbol shaper in the transmitter side in addition to equalization and combining processes in the receiver side. Comparative study between the proposed system and the conventional OFDM in case of additive white Gaussian noise (AWGN) and COST 207 typical multipath fading channel will be presented. The numerical results show that the proposed STC-Shaped scheme reduces OOB significantly. The proposed scheme improves BER in multipath Rayleigh fading although it is without CP. Thus, the proposed system is more robust against inter symbol interference (ISI) compared to conventional OFDM system. Also, the numerical results show that the PAPR of the proposed system is decreased significantly and also, it is derived theoretically. Also, the proposed scheme overcomes CP extension, and hence increases the bandwidth (BW) efficiency. Finally, the computational complexity for the proposed scheme is derived and it has very low complexity compared to FBMC. The system performance measurments has been fulfilled using cumulative distribution function (CDF), power spectral density (PSD) and bit error rate (BER).

An Effective Technique for Increasing Capacity and Improving Bandwidth in 5g Nb-Iot

“…As seen in Fig. 7 (b), using C-STC-OFDM in [26] reduces the time required to process an OFDM symbol by 50% when compared to a conventional OFDM system. While, using the suggested approach (M-STC-OFDM) significantly reduces the time required for each OFDM symbol by 75% when compared to conventional OFDM system and 50% when compared to C-STC-OFDM system, as it is clear in Fig.…”

“…Multiplications No. Additions Conventional OFDM [26] 2N Log 2 N -2N 3N Log 2 N -N C-STC-OFDM [26] N Log 2…”

Doubling the Number of Connected Devices in Narrow-band Internet of Things while Maintaining System Performance: An STC-based Approach

“…The following assumptions are applied to calculate complexity: i) the complexity of subtraction equals the complexity of addition and ii) the complexity of division equals the complexity of multiplication. In the conventional OFDM system, it requires a total of (3N * log 2 N − N) additions and (2N * log 2 N − 2N) multiplications [36]. The Fast OFDM system has the same sub-carriers compared to the conventional OFDM system.…”

Performance improvement for DCO-OFDM and ACO-OFDM systems using symbol time compression

“…At the receiver terminal, the combining and the symbol time expansion (STE) processes are performed. Using the STC system, the OFDM symbol is compressed into one half [20][21][22]. Hence, the number of subcarriers become 𝑁 2 ⁄ .…”

“…There are many applications for the STC scheme in RF communications, such as ICI reduction for OFDM systems caused by high mobility [20], ICI cancellation using a time inversion scheme (TI) [21]. The STCshaped scheme for OOB reduction, PAPR reduction, CP elimination, and ISI reduction in wireless channels [22]. In addition to this, the STC-shaped scheme is used for green communication in another way [23].…”