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| 1 SiFT (Simple Forwarding over Trajectory) Routing |
| 2 -------------------------------------------- |
| 3 |
| 4 SiFT can be considered as a routing/forwarding protocol with very low overhead i
n computation for using in wireless ad hoc networks |
| 5 |
| 6 This model was developed by· |
| 7 `the ResiliNets research group <http://www.ittc.ku.edu/resilinets>`_ |
| 8 at the University of Kansas.·· |
| 9 |
| 10 SiFT Routing Overview |
| 11 ************************** |
| 12 This model is based on specification written in [1]. There is no standard or RFC
for this model currently. |
| 13 |
| 14 SiFT can be considered as a reactive protocol and operates on a on-demand behavi
or. This model doesn't keep any routing table and works based on control floodin
g which is broadcasting in a controlled way. Nodes need to know geolocation of e
ach other and we use sift-geo class to get the proper information from other nod
es. Authors of the model have been assumed that these information can be retriev
ed by GPS or any other similar techniques;however, they haven't specified any pa
rticular method. |
| 15 |
| 16 By knowing geolocation of the source and destination, the source calculates a tr
ajectory to the destination and adds these geographical information to each pack
et. Therefore, each node that receives these packets can calculate the trajector
y. This information plus geolocation of the last sending nodes are added to a he
ader above the IP header. When a node receives a packet, it calculates its dista
nce from the trajectory and the last sending node and set a timer based on these
values. The node which has the less value for its timer forwards the packet and
other nodes which are in its wireless range and waiting for their timer to time
out stop their timer and consequently the forwarding process. Therefore, nodes w
hich are closer to the trajectory and farther from the last sending nodes forwar
ds the packet. In order to eliminate transmission of those nodes that are far fr
om the trajectory and out of the wireless range of the forwarding node, they sto
p forwarding process, if their distance from the trajectory are more than a defi
ned threshold. This threshold can be as long as the wireless range of each node.
The whole calculation is done by a simple formula which divides the node distan
ce from the trajectory and the last forwarding node. Therefore, mobility of node
s can be considered in each forwarding process and it is not necessary to keep a
ny extra information. In other words, those node which are closer to the traject
ory forward the packets. It can be considered broadcasting along the trajectory. |
| 17 |
| 18 Although pairwise lines can also be used for the trajectory and they are suitabl
e for paths like vehicular networking, we don't implement it. |
| 19 |
| 20 Useful Defined Parameters |
| 21 ************************* |
| 22 |
| 23 +-----------------------------------------------------------------------------
--------------------+ |
| 24 | Parameter | Description
| Default
| |
| 25 +---------------------+-------------------------------------------------------
+-------------------+ |
| 26 | ALPHA | A constant value in SiFT formula
| 0.001 | |
| 27 | |
| | |
| 28 +---------------------+-------------------------------------------------------
+-------------------+ |
| 29 | TRANSMISSION_TIME | Transmission time based on wireless range 250m
| 0.00047 | |
| 30 | |
| | |
| 31 +---------------------+-------------------------------------------------------
+-------------------+ |
| 32 |
| 33 SiFT in ns-3.23 |
| 34 *************** |
| 35 SiFT is implemented in ns-3.19 and tested on ns-3.21, ns-3.22 and ns-3.23 as wel
l. We can not find any incompatibility in any of these versions. Moreover, we co
mpare the SiFT performance with other available adhoc routing protocols in ns-3
without any problem. The results are available at [2] |
| 36 |
| 37 Helper |
| 38 ****** |
| 39 In order to use SiFT the following Helpers have been implemented: |
| 40 |
| 41 SiftHelper |
| 42 SiftMainHelper |
| 43 |
| 44 SiftHelper: A helper class to make life easer for people who want to install sif
t on nodes······ |
| 45 SiftMainHelper: A helper class to manage SiftHelper functionality· |
| 46 |
| 47 The example scripts inside ``src/sift/examples/`` demonstrate the use of sift ba
sed nodes in different scenarios.· |
| 48 The helper source can be found inside ``src/sift/helper/sift-main-helper.{h,cc}`
` and ``src/sift/helper/sift-helper.{h,cc}`` |
| 49 |
| 50 |
| 51 Example |
| 52 ******* |
| 53 Two examples are found in ``src/sift/examples/``: |
| 54 |
| 55 * siftSample.cc is a simple script to simulate SiFT in a 2D environment with 10
nodes. |
| 56 * sift.cc is a more general script which let the user to change the routing algo
rithm, the size of area an the mobility pattern of nodes. It can be used to comp
are SiFT with other implemented algorithms such as AODV and DSR. |
| 57 |
| 58 |
| 59 |
| 60 Validation |
| 61 ********** |
| 62 Simulation cases similar have been tested and have comparable results. |
| 63 manet-routing-compare.cc has been used to compare SiFT with three of other routi
ng protocols. |
| 64 |
| 65 The results are available in a technical paper at [2]. |
| 66 |
| 67 References |
| 68 ********** |
| 69 [1] Link for main paper <http://home.deib.polimi.it/filippini/papers/2005_ISWCS_
Sift.pdf> |
| 70 [2] Link for SiFT comparison results < http://www.ittc.ku.edu/resilinets/reports
/Modarresi-Sterbenz-2015.pdf> |
| 71 |
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