HINNING OF POISSON PROCESS TO ACHIEVEENERGY EFFICIENCY
The energy efficiency of the system can be improved bylimiting the number of nodes per level that relay the infor-mation. Usually for a network with a high node density, thetransmissions from all the DF nodes of one level are notrequired for the formation of the next level. Similar results canbe achieved by having a limited node participation at differenthops. The nodes present near the source or the boundary ofprevious level have much higher received powers owing toless average path loss and when they transmit to the nextlevel nodes, their transmissions have little or no effect onthe decoding of the nodes of next level because of largepath loss between them and the next level nodes. Limitingsuch nodes from transmission to the next level and allowingonly those nodes which are nearer to the next level boundary,conserves a significant amount of energy. A threshold basedcriteria is used to limit such nodes, i.e., only those nodesare allowed to transmit whose SNR margin is greater thandecoding threshold and less than an upper bound threshold.Hence in this section, we devise a method to improve theenergy efficiency of the network by having limited nodeparticipation.
The nodes in one level are divided into two subsets of trans-mitters based on the above criteria, i.e., effective transmittersand futile transmitters as shown in Fig. 5. The two subsetsof the transmitters do not need to be of equal sizes. Theirsizes can vary, however, increasing the number of nodes inone subset decreases the number of nodes in the other andvice versa. The size of two subsets can be made dependentupon the quality of service (QoS),η, and other networkparameters. The QoS in this case can be defined as the mini-mum end-to-end success probability required for the network.We devise the thinning of OLA (Th-OLA) algorithm, whichis derived from the basic OLA with additional constraint fortransmission that the nodes must be closer to the boundaryof the next level. This type of situation can be attributed to alarger rectangular area, where nodes are distributed accordingto a PPP, but for transmission purpose, only the nodes ofa smaller rectangular area are selected as shown in Fig. 6.We consider the following the theorem for the thinningof PPP. Code Shoppy
We have developed and analyzed a spatial Poisson point pro-cess model for a strip-shaped cooperative multi-hop networkwith random number of nodes and irregular hop boundaries inthe presence of path loss and Rayleigh fading. The Euclideandistance distribution between two randomly located nodes inadjacent levels is derived and approximated with the Weibulldistribution for a tractable solution. An analytical expressionfor the PDF of the received power at a node is derived by selfconvolving the ratio of an exponential RV and a Weibull RVover a PPP. The received power distribution is used to ana-lyze the network in terms of the one-hop success probabilityand them-hop success probability. The analytical model issuccessful in predicting the coverage range of a pure OLAnetwork under a quality of service constraint. We proposedan energy efficient algorithm based upon the thinning of thetotal transmitters in one level. It is shown that our algorithmsaves a significant amount of energy when compared withbasic OLA and it is more efficient than independent thinning.A future direction of this work would be to study the effectsof multiple packets transmission in OLA that may induceinterference and limit the coverage probability. The effect ofshadowing and variable transmit power on the coverage ofnetwork is another important direction.