Q2. What future works have the authors mentioned in the paper "The message delay in mobile ad hoc networks" ?
Future research will focus on the message delivery within a certain timeframe, the inclusion of queueing delays, non-homogeneous scenarios ( nodes have a different or a changing transmission range ), the inclusion of interference and transmission times, and the study of other mobility models ( two-dimensional, three-dimensional, or on a sphere ).
Q3. What is the expected message delay under the unrestricted multicopy protocol?
(12)Under the unrestricted multicopy protocol, the expected message delay isE[TU] = 1 λN N∑ i=1 1 i = 1 λN ( log(N) + γ +O ( 1 N )) , (13)where γ ≈ 0.57721 is Euler’s constant.
Q4. What is the proof of the two-hop multicopy protocol?
For both the two-hop and the unrestricted multicopy protocols the proof is based on modeling the number of copies in the network as an absorbing finite-state Markov chain.
Q5. What is the expected delay under the two-hop relay protocol?
Since λ = O(r(N)) for the random waypoint model, and with the scaling r = O(1/√N), the authors find that the expected message delay under the two-hop relay protocol is O( √ N), just as was found in [14] but for nodes moving on a sphere.
Q6. What is the expected message delay for the two-hop multicopy protocol?
In [14] it is shown that, under the two-hop relay protocol, the expected message delay is of the order nTp(n) for the random waypoint mobility model on a sphere (where n is the number of nodes per unit area and Tp(n) is the transmission time of a message).
Q7. Why is the exponential tail a problem for the random walker mobility model?
Because of the quick emergence of the exponential tail for the random walker mobility, the authors have included it in their analysis to see how robust their model is.
Q8. What is the expected number of copies under the two-hop multicopy protocol?
The expected number of copies under the two-hop multicopy protocol is given by (cf. (2) and (12))E[N2] = 1 N N∑ i=1 i2 Ni N! (N − i)! = √ πN 2 +O(1). (14)Hence E[N2] = λNE[T2].
Q9. What is the cdf for the random direction and the random waypoint models?
The parameter λ for the random direction (RD) and the random waypoint (RW) mobility models is given byλRD ≈ 2rE[V ∗]L2 , and λRW ≈ 2ωrE[V ∗] L2 , (15)respectively, for values of r L.
Q10. What is the expected message delay for each protocol?
This result shows that for each protocol the expected message delay is a linear function of the expected inter-meeting time 1/λ, and changing the value λ does not have any impact except for a time scaling.
Q11. What are the expected message delays for the two-hop multicopy protocol?
6 and 7 display the expected message delays obtained both through simulations and by the analytical model as a function of the number of nodes.
Q12. What is the general description of the performance of mobile ad hoc networks?
The performance of mobile ad hoc networks is in general studied via lengthy and complex simulations, for a limited number of mobility models, including the random waypoint mobility model [3] or the random direction mobility model [1,8].