## 1 Introduction  
The millimeter-wave (mm-wave) and radio over fiber (RoF) capabilities have been developed to improve the speed and the ability to meet high traffic requirements in the last few years. The mm-wave signal generation is essential to achieve high data rates, in addition to other advantages such as low attenuation, large bandwidth, and low cost [1, 2, 3]. The massive increase in bandwidth with the huge number of connected devices causes problems in most communications systems. Therefore, the mm-wave RoF has been promoted as a bandwidth and infrastructure solution that can meet the requirements of high-speed wireless systems such as fifth generation (5G) networks [4, 5]. The features of mm-wave RoF systems, such as low latency and high bit rates, are suitable to realize the vision of the centralized-radio access network (C-RAN) [6]. In addition, the RoF system is also an option for the integrated system to connect with C-RAN fronthaul networks [7]. Recently, several studies have suggested distributing the wireless signal with different techniques over the mm-wave RoF downstream systems. The techniques were developed based on the heterodyne optical phase-locked loop [8], Stimulation Brillouin Scattering (SBS) [9, 10], the optical single side band (OSSB) [11, 12, 13] and Dual-side band Optical Carrier Suppression (DSB-OCS) [14; 15]. All these studies generated the mm-wave optically and utilized it in signal transmission. It was, however, noted that none of them examined the effect of modulation index on the system or the effects of optical fiber dispersion on optical mm-wave networks as well as the phase imbalance, which is crucial. Therefore, there are more parameters and more efficient techniques to be investigated to ensure an excellent system for the future. On the other hand, the DSB-OCS technique is worth exploring for this reason because it generates the mm-wave signal using just a fraction of the local oscillator (LO) at the base station (BS) [16]. Additional advantages of the DSB-OCS system are an ability to generate mm-wave signals with tunable frequencies [17], greater spectral efficiency [18], and lower mm-wave component requirements to generate the mm-wave carriers [19]. Overall, the choice of using the mm-wave method is to reduce the central station (CS) model complexity and reduce the remote antenna unit (RAU) size. Several studies have suggested that both Analog-RoF (A-RoF) and Digital-RoF (D-RoF) technologies have their advantages and disadvantages [6; 20; 21]. However, this paper presents the DSB-OCS technique in A-RoF with the intention to improve its performance, reduce the RAU complexity and enhancing system flexibility [22]. Moreover, it is still possible to convert A-RoF to D-RoF [23], or combine both A-RoF and D-RoF in one system [24]. This way, the benefits for both the analog and digital can be shared together with vast bandwidth in the optical domain to be offered to the wireless counterpart. Prior research on DSB-OCS has pointed towards the need to enhance the current techniques to reach higher mm-wave frequency with higher bandwidth and capability through RoF systems. A high-order RF multiplier was used to generate the mm-wave in the DSB modulation for the Maximum Transmission Bias Point (MATB) in [25], which focused on the odd harmonics. In that study, a dual-parallel Mach-Zehnder modulator was used which led to some insertion losses and managed to generate 30 GHz and 60 GHz signals. On the other hand, this study focuses on determining the right modulation index to produce the maximum mm-wave output with the help of Bessel function in the DSB-OCS system, and studying the effect of dispersion and phase imbalance in such a system. The modulation index and the dispersion of the DSB-OCS parameters are considered as essential parameters to evaluate the hybrid network performance [26]. Firstly, when the power of the broadband signal injected into the system is increased, more intermodulation products are produced, which results in interference.