## 2 Data and Methods
Demands on the network may not require 100 Gbps capacity everywhere, therefore, a cost-effective network design should take advantage of the possibility of mixed line speeds (MLR), in wavelength division multiplexed networks (WDM), which increase the capacity of a wavelength to 100 Gbps and present a trade-off between capacity and range [11]. Managing a type of transparent optical architecture, where the signal remains in the optical domain all the time; therefore, electronic signal processing is not necessary in intermediate nodes or, on the contrary, they can be of the opaque type, where each node has electronic regeneration [12]. Figure 1: Optical Behavior Relationship in terms of Adapted Information Theory [9]. Various studies have been developed to improve the performance of MLR networks, among which the separation values between channels stand out, considering [12]: (i) a uniform 50 GHz fixed channel spacing specified by ITU-T, (ii) various channel spacing values for different line speeds to optimize the use of spectrum fiber, or (iii) defining an optimal spaced channel value, which results in the minimum cost of the network. It has been shown that as the spacing increases, the cost of the network in terms of transponders decreases up to a certain optimal channel spacing [13]; the chromatic dispersion coefficient is considered to be 17 ps/nm x km, and the PMD (polarization mode dispersion) coefficient of 0.06 ps/nm x km. Based on the previous information and previous studies, the base network model to use is unidirectional point-to-point WDM, which incorporates multiple modulation formats, with a fixed grid between channels and mixed line speeds (MLR). It has a uniform physical layer infrastructure, with different types of transponders, which can carry signals of 2.5 Gbps, 10 Gbps, 20 Gbps, and 40 Gbps, multiplexers (MUX), a single-mode fiber (SMF), a compensation module of chromatic dispersion fiber (DCF), a demultiplexer (DEMUX), and receivers (RX) that sequentially coincide with the corresponding transmitters, to generate and analyze the different case studies with a target distance of 80 km to 120 km, according to the G. 691 of the ITU. In addition, in order to guarantee a quasi-linear propagation environment, where the effects of linear types predominate, which are characterized by being constant in time and depend on the manufacturing and medium characteristics, the decision is made to work with very low powers close to 0 dBm and not implementing on-line amplification processes to avoid the excitation of their penalties, in addition, a good receiver is used, whose sensitivity allows the received power to be low. In the linear regime, the spectral efficiency limit is independent of chromatic dispersion, because it is possible, in principle, to fully compensate for dispersion at the receiver [6]. In the non-linear regime, impairments limit transmission distances, such as the Kerr effect, which has the greatest impact on channel capacity, where the added optical signal intensity disturbs the refractive index of the fiber, thus modulating the fiber's refractive index. signals phase. Some research has argued that the capacity of DWDM systems is fundamentally limited by XPM, since as a signal propagates, chromatic dispersion converts the XPM-induced phase modulation into intensity noise [6]. Nonlinear effects derived from the reduction of the space between channels and a greater number of channels will be one of the major impediments in wavelength division multiplexing [14]. Regarding modulation formats, it has been verified that on-off keying (OOK) presents higher performance at low speeds of 10 Gbps or lower, while at high speeds, such as