Queing of packets in realtime is based on the setting of immediate flag will results ditrubence for the normal queing process..

And in non realtime the packets queing will be distrubed by the time stamp of the packet got generated

Do you know some works about?

Instant

WSN don't provide real Quality-of-Service guarantees.

Strict QoS guarantees are require a full hardware and protocol integration, which is only possible in embedded systems.

You should look into scheduling for realtime embedded systems.

Probabilistic QoS guarantees are easier to provide and there is a lot of documentation on scheduling and MAC protocols for WSN.

sure that providing QoS in WSNs is a big challenging point and can't be absolutely guaranteed, but our gol was always to maximize the QoS performance ,

my actual work concern the network layer and i m developping a multipath routing protocol which provide some of QoS requierements such as delay, throughput, bandwidht, etc

for that i need more informations about the queing techniques used in WSNs and precisely priority models for classifying the pakets( real and non real time pakets)

Maybe this would be useful: http://www.springerlink.com/content/0j2714323h446pr6/

A queuing network model is probably a good starting point.

As for developing a proper model, you have to have the full stack not just the network layer. A network simulator such as ns-2, ns-3 or omnet++ is probably a good choice.

On a general note, to have QoS guarantees, you need a packet classifier and shaper that splits the traffic into 2 or more queues. The shaper is required to fit the traffic into maximum guaranteed data rates, dropping or lowering priority of out-of-profile packets. On the other side of the queues there is a scheduler that sets the priorities between the queues. This is usually a weighted round robin scheduler. The weights can also be adaptive if the system reacts to changing network conditions. The scheduler delivers the packets to the lower layers in the correct sequence given the defined scheduling algorithm.

thanksMr Gayathri, but i think the paper speak about queing in an athor aspect , i mean that it speaks about queing pakets in the nodes buffers but not for the communication phase or no??

i think you needed some real time scheduling policies...r8. if it so, some queuing and scheduling policies are:

1.velocity monotonic scheduling (refer: RAP routing protocol)

2.Earliest Deadline first.

3.Just in time Scheduling (JiTs)...etc..

Hope this may be useful....

Can you explain more??

Actually, "RAP " named one real-time routing protocol is there, in that architecture authors used a novel real-time packets scheduling policy named: "Velocity monotonic scheduling" which meets the differentiation service for real time, and non real time, priority scheduling . for the detailed explanation, just follow the link:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA436746.

like wise, some other real-time queing/buffer management and packet scheduling algorithms are there.

for eg:

Earliest deadline first

Just intime scheduling (JiTs)..etc.

(refer more from internet source..)

hope it will be useful to you..

Thanks so much

RAP is designed for large scale wireless sensor network with velocity monotonic scheduling as a packet scheduler. there are more packet scheduling schemes like multilevel priority scheduling and dynamic multilevel scheduling scheme. there main aim is providing quality of service while reducing sensor node energy consumption by classifying packets according to their requirement as a real time and non-real time packet and increasing service rate of higher priority packet more specifically real time packets need to be given higher priority and service rate.

but I do have one question for any one following this question:

what is the criteria to identify packets as a real time and non-real time in case of wireless sensor simulation?