Method and apparatus for optimizing a queue based cross layer in a wireless ad-hoc network
View Patent ↗A method and apparatus for optimizing a cross layer in an ad-hoc wireless network are provided. A link price is set using the number of packets of a queue. A flow rate is set using the link price. A channel access rank is set by comparing the link price with a link price of a neighboring node. A channel access backoff time is set based on the channel access rank. The method and apparatus for optimization may not be subject to interference and can simultaneously obtain fairness and efficiency while adaptively setting link capacities.
1. A method performed by an apparatus for optimizing a cross layer in an ad-hoc network, the method comprising:
setting a link price using a number of packets of a queue;
setting a flow rate using the link price;
setting a channel access rank by comparing the link price with a link price of a neighboring node; and
setting a channel access backoff time based on the channel access rank.
2. The method of claim 1 , wherein the setting of the link price comprises:
periodically monitoring a size of the queue; and
computing the link price using a queue based pricing algorithm.
3. The method of claim 1 , wherein the setting of the link price comprises estimating an average link price based on an old link price.
4. The method of claim 1 , wherein the setting of the link price comprises performing computation using a moving average method defined by:
λ l ( t +1)=[(1−α)·λ l ( t )+α· q l ( t )] + ,
wherein α is a small positive integer, q is the number of packets in a queue of a link l λis a price of the link l, t is a particular time, and + is an operator for taking only an integer part computed by discarding the part after a decimal point in a real number.
5. The method of claim 1 , wherein the setting of the flow rate comprises setting the flow rate using the link price of the neighboring node.
6. The method of claim 1 , wherein setting of the flow rate comprises setting the flow rate using the price of the neighboring node derived from packet information broadcast from the neighboring node.
7. The method of claim 1 , wherein the setting of the flow rate comprises setting the flow rate using a flow price, the flow price being set using an old flow price.
8. The method of claim 1 , wherein setting of the flow rate comprises setting the flow rate using a flow price, a utility function and a rate control factor.
9. The method of claim 1 , wherein setting of the flow rate comprises setting the flow rate using a flow price, the flow price being defined by:
λ
s
=
∑
l
∈
s
∑
n
∈
N
(
l
)
λ
n
and
λ
_
s
(
t
+
1
)
=
[
(
1
-
β
)
·
λ
_
s
(
t
)
+
β
·
λ
s
(
t
)
]
+
,
wherein n is a neighboring node of a link l belonging to a flow s , β is a small positive integer, w is a rate control factor for controlling a queue size and a flow rate, t is a particular time, + is an operator for taking only an integer part computed by discarding the part after a decimal point in a real number, λ is a price of the link l, and λ s is a finally saturated value.
10. The method of claim 1 , wherein setting of the flow rate comprises setting the flow rate using x s =max(x max ,U l−1 ( λ s )·w),
wherein x is the flow rate, U is a utility function, λ is a link price, w is a rate control factor, and λ s is a finally saturated value.
11. The method of claim 1 , wherein the setting of the channel access backoff time comprises:
broadcasting a computed price based on the queue to the neighboring node;
setting the channel access rank by receiving a price from the neighboring node and comparing the computed price with the received price; and
setting the channel access backoff time using the channel access rank.
12. The method of claim 1 , wherein the setting of the channel access backoff time comprises computing the channel access backoff time defined using:
backoff i =rank( i )· cw ( r )+└Rand( )· cw ( r )┘×SlotTime
wherein rank (i) is a rank of a node i, cw(r) is a contention window (CW) value used at an r-th reattempt, Rand is an arbitrary value between 0 and 1, and SlotTime is a time of a slot.
13. The method of claim 1 , further comprising:
receiving a subsequent flow and updating the link price; and
updating the flow rate using the updated link price.
14. A computer-readable recording medium storing a program for implementing the method of claim 1 .
15. An apparatus for optimizing a cross layer in a wireless ad-hoc network, the apparatus comprising:
a memory for storing information comprising a number of packets of a queue; and
a controller, connected to the memory, for controlling cross-layer optimization, the controlling includes setting a link price using the number of packets of the queue, setting a flow rate using the link price, setting a channel access rank by comparing the link price with a link price of a neighboring node, and setting a channel access backoff time based on the channel access rank.
16. The apparatus of claim 15 , wherein the controller sets an average link price and an average flow rate using old values.