1. A system for providing an online optimization for a cognitive wireless network using a qualitative model, the system comprising: a processor; a memory coupled to the processor, wherein the processor executes programmed instructions stored in the memory for: capturing network state information comprising a plurality of state variables, driven by the qualitative model; identifying, from the plurality of state variables, a goal variable, a plurality of intermediate variables, and a plurality of control variables; forming a monotonic signed directional acyclic graph (MSDAG), in form of hierarchy of nodes, comprising the goal variable, the plurality of intermediate variables, and the plurality of control variables represented in form of a plurality of pair of nodes, wherein each pair of nodes is connected via an edge having a monotonic information indicated in form of a +ve sign or a −ve sign; simplifying the MSDAG in order to generate a simplified MSDAG, wherein the simplified MSDAG is generated by a) removing superfluous nodes corresponding to one or more intermediate variables that does not include a predefined constraint, and b) replacing a path associated with the superfluous nodes with an edge having an effective path influence, wherein the effective path influence is a product of the monotonic information of edges forming the path; identifying one or more control variables from the plurality of control variables, present in the simplified MSDAG, as conflicting variables and non-conflicting variables, wherein the conflicting variable indicates a control variable having multiple paths to the goal variable; assigning an active constraint, to a conflicting control variable having a non-conflicting path with the goal variable, for guiding movement of the conflicting control variable in said path, wherein the active constraint corresponds to a value within an operating range of the network; and optimizing the cognitive wireless network by applying a Monotonic Signed Directional Acyclic-Graph based sequential algorithm (MSDAG-SOPT) on the simplified MSDAG, wherein the MSDAG-SOPT comprises a) selecting a path, of the multiple paths, for the conflicting variables, wherein the path comprises multiple intermediate variables having predefined constraints, b) identifying an intermediate variable, having the active constraint, amongst the multiple intermediate variables, nearest to the control variable in the hierarchy of nodes, wherein the intermediate variable is a conflicting control variable from among the conflicting control variables, and c) updating the one or more control variables based on the monotonic information associated with the path, wherein at least one conflicting control variable identified as conflicting is updated until the predefined constraint associated with the intermediate variable is satisfied.