Methods and system for modeling wireless communications in a network
View Patent ↗The embodiments relate to modeling wireless communications in a network. In wireless communications, the nodes share one or more wireless communication channels. When a node has data to transmit, it must contend with the other nodes for access to the wireless communication channel. In the embodiments, the model is configured to simulate the throughput effects of contention including delays caused by retransmissions due to interference and collisions, listen-and-backoff, unavailability of time slots, etc. The occurrence of failed/dropped transmissions due to buffer overflows, excessive retransmission attempts, and unintended collisions are modeled as well. In addition, the embodiments may simulate the effect of mobility by the nodes and the effect of the location of the nodes relative to each other.
1. A computer-implemented method of simulating performance of a network, wherein the network comprises a plurality of wireless nodes that communicate with each other via a wireless communication channel having a predetermined range, wherein the wireless nodes are modeled based on the their location relative to the range of the wireless communication channel, and wherein the wireless communication channel is modeled based on a bandwidth provided to the wireless nodes that is affected by contention, said computer-implemented method comprising:
simulating traffic comprising messages to be transmitted by at least some of the wireless nodes in the network;
determining nodes in the network that are reachable by the wireless communication channel;
determining a contention measure for the wireless communication channel based on the nodes that are reachable;
determining, from a model of the wireless communication channel that is common to the wireless nodes using the wireless communication channel and characterizes throughput in which the wireless nodes using the wireless communication channel are operating as a function of the contention measure, a set of throughput parameters available from the wireless communication channel to the reachable nodes based on the contention measure; and
determining a throughput of the simulated traffic provided by the network based on the set of throughput parameters.
2. The method of claim 1 , wherein determining nodes in the network that are reachable comprises:
determining a position in the network of a transmitter that provides at least a portion of the wireless communication channel within a predetermined range;
determining a location of the nodes relative to the position of the transmitter; and
determining reachability of the nodes based on nodes that are located within the predetermined range.
3. The method of claim 2 , wherein determining a position of the transmitter comprises determining the position of the network based on a time interval.
4. The method of claim 2 , wherein determining nodes in the network that are reachable comprises:
receiving an update to the position of the transmitter; and
determining the nodes that are reachable based on the updated position of the transmitter.
5. The method of claim 4 , wherein determining the nodes that are reachable comprises determining the nodes that are reachable based on when the updated position of the transmitter has changed by at least a threshold amount.
6. The method of claim 1 , wherein determining the contention measure comprises determining a number of reachable nodes that are contending for access to the wireless communications channel.
7. The method of claim 1 , wherein determining the contention measure comprises setting the contention measure at an initial fixed value.
8. The method of claim 1 , wherein determining the contention measure comprises setting the contention measure based on an average number of reachable nodes.
9. The method of claim 1 , wherein determining the contention measure comprises setting the contention measure based on the number of reachable nodes.
10. The method of claim 1 , wherein determining the contention measure comprises setting the contention measure based on a proportion of the number of reachable nodes.
11. The method of claim 1 , wherein determining the set of throughput parameters available from the wireless communication channel comprises determining an available bandwidth from the wireless communication channel based on the contention measure.
12. The method of claim 1 , determining a set of throughput parameters available from the wireless communication channel comprises determining a probability of drop of a message in the simulated traffic based on the contention measure.
13. The method of claim 12 , wherein determining the probability of drop comprises determining a probability of drop of a unicast transmission of a message.
14. The method of claim 12 , wherein determining the probability of drop comprises determining a probability of drop of a multicast transmission of a message.
15. The method of claim 1 , wherein determining the throughput of the simulated traffic comprises determining a service delay in transmitting message by the wireless nodes based on the throughput measures.
16. The method of claim 1 , wherein determining the throughput of the simulated traffic comprises determining drop of packets in messages based on the throughput measures.
17. A simulation system for simulating communications among a plurality of nodes in a network, wherein the network comprises a plurality of wireless nodes that communicate with each other via a wireless communication channel having a finite range, said simulation system comprising:
a first set of models respectively modeling media access by each of the wireless nodes in the network and locations of the wireless nodes in the network;
a second model of a wireless communication channel that is common to the plurality of wireless nodes and configured with the finite range, wherein the second model provides an output indicating throughput available from the wireless communication channel that is affected by contention;
a processor configured by executable program code to simulate traffic comprising messages to be transmitted by at least some of the wireless nodes in the network, determine, from the first set of models, nodes in the network that are reachable by the wireless communication channel, determine, from the second model, a contention measure for the wireless communication channel based on the nodes that are reachable, determine, from the first set of models, a set of throughput parameters available from the wireless communication channel to the reachable nodes based on the contention measure, and determine a throughput of the simulated traffic provided by the network based on the set of throughput parameters.
18. The system of claim 17 , wherein the first set of models determines nodes in the network that are reachable based on executable program code for determining a position in the network of a transmitter that provides at least a portion of the wireless communication channel within a predetermined range, determining a location of the nodes relative to the position of the transmitter; and determining reachability of the nodes based on nodes that are located within the predetermined range.
19. The system of claim 17 , wherein, the second model is configured to determine the contention measure based on a number of reachable nodes that are contending for access to the wireless communications channel.
20. The system of claim 17 , wherein the first set of models is configured to determine a set of throughput parameters available from the wireless communication channel based on determining a probability of drop of a message in the simulated traffic based on the contention measure from the second model.
21. The system of claim 17 , wherein the first set of models is configured to determine the throughput of the simulated traffic based on determining a service delay in transmitting message by the wireless nodes based on the throughput measures.