Wireless Ad Hoc and Sensor Networks

196 Wireless Ad Hoc and Sensor NetworksAll links are assumed to attain the same target value for SIR definedas γ = 5. Each new link, at a random time instant, tries to attain thetarget SIR starting with an initial power value of p i = 10 −5units. An upperlimit on the power with which each link transmitter can transmit is setas p max = 5 units. Each new link is given a predefined amount of admissiontime T i to achieve the target SIR. If it is able to attain the target SIRduring T i , it is declared active, allowed to transmit to the receiver for acertain predefined amount of service time; and thereafter, it terminatestransmission. Optimal power control and SSCD schemes allow the newlinks to gradually power up and attain the target SIR value. The schemesmaintain the SIR value of the active links above the target γ while thenew links are gaining access to the channel. A new link, according tothe scheme, is admitted only if it maintains the system’s stable stateeven after its addition.Several scenarios are considered, and the proposed DPC/ALPschemes are evaluated. In SSCD and optimal control schemes, in additionto error in SIR Equation 5.12, the cumulative sum of errors (El-oseryand Abdullah 2000) is also considered for the simulation. As a result,the feedback gains are selected as ki = [ k1 k2].To compare the performanceof our scheme with that of Bambos et al. (2000), the simulationenvironment is chosen as seen in Figure 5.11. Eleven nodes with500S-Transmitting node (source) & R-Receiving node4504004S4R9S9RDistance in meters3503002502001501001S2S1R3S2R3R6S7S6R8S7R8R5010S 10R 5S 5R 11S 11R00 50 100 150 200 250 300 350 400 450 500Distance in metersFIGURE 5.11Link placements.