## 1 Introduction  
The fifth generation (5G) technology is about to be launched soon to match the user demand and various requirements of future wireless communications [1]. Besides the machine type communications for ultra-reliability and low latency, enhancing mobile broadband is considered as a main research topic toward the next-generation communication network for 5G [2]. In this context, information-centric network (ICN) is regarded as a promising future Internet design with the key innovative features including in-network caching and name-based forwarding to improve the network efficiency [3]. However, by default, ICN requires caching-enabled routers which consume higher power compared to the traditional host-to-host architecture as analyzed in our previous work [4; 5; 6]. Also, the original forwarding strategy in ICN, leave copy everywhere (LCE), produces high cache redundancy that discourages ICN feasibility for the real-world deployment [7]. Different attempts were then made to realize the new modulation spectrum with high efficiency for next-generation communications. Particularly, orthogonal frequency division multiplexing (OFDM) is used in 4G to increase the modulation capacity and feed multi-user synchronically. For 5G, the modulation is usually conducted in non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) to realize the feasible alternative modulations [8]. Another potential research trend in 5G is to improve the OFDM scheme by adjusting its structure to fulfill the requirements of 5G such as guard interval discrete Fourier transform and spectrally-preceded OFDM, namely GI DFT-s-OFDM and SP-OFDM, respectively [2; 9]. The four single-sideband (4-SSB) [10; 11] is another notable work in OFDM which has an advantage of sending double the amount of similar information using only half of the bandwidth compared to other OFDM modulations. The 4-SSB technology can be extended by using a Hilbert transform which allows the generation of the single-sideband (SSB) from different types of modulation like phase shift keying (PSK), quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM). However, to the best of our knowledge, this innovative idea of using the SSB technique has not been applied for 5G communications. Toward this end, we have investigated how QAM modulation can allow a communication system to improve the data rate to match 5G requirements [12]. Hence, in this research, we aim to increase the communication bandwidth by moving toward the combined 4-SSB signals generated from two symbols of QAM. This proposal then can increase the spectrum efficiency through QAM by applying the novel idea of 4-SSB in multiple-input multiple-output (MIMO). The proposal complexity can be minimized by redesigning the receiver side, particularly in the equalizer. Typically, we apply a new algorithm in the 4-SSB system, called shadow equalizing. By simulation, the new design demonstrates the low complexity by removing the process of the decoder and interleaver in iteration loops needed for the turbo equalizer. This process also refers to low energy consumption by ascending hardware component in the receiver side [13]. In our prior research [12], we successfully transmitted 16-QAM and 64-QAM through an additive white Gaussian noise (AWGN) environment and multiple path fading channels. The evaluation results show that the M-QAM 4-SSB OFDM can increase channel capacity and data rate. Thus, SSB modulation is a promising candidate to improve efficiency in the 5G network. Currently, most studies have applied SSB modulation for fiber optics to enable high-speed data rate and increase capacity [14]. However, they also verify that the intersymbol interference (ISI) is the critical issue in SSB-based modulation for the wireless channel.