Handoff metric for multiple transmission technologies
View Patent ↗Provided are methods and systems of managing a handoff in a multimedia communication network. Embodiments include estimating the voice quality of a communication route in the network. The voice quality may be estimated by using a total voice quality metric involving subtracting various impairments to the voice signal. Impairments may result from the type of vocoder in a communication route, the error or loss associated with RF links and network links, and delays in the communication route. After subtracting the impairments to obtain the total voice quality metric for the communication route, the total voice quality metric may be compared with a threshold and/or other total voice quality metrics of other communication routes to determine whether and when a handoff should be made.
1. A method of managing a handoff in a multimedia communication network, the method comprising: computing a vocoder impairment based on the vocoder selected for a communication route in the network; computing a radio frequency (RF) link impairment based on one or more RF links selected for the communication route; computing a subnetwork impairment based on the subnetwork selected for the communication route; computing a delay impairment based on a total delay incurred in transferring data through the selected vocoder, the selected one or more RF links, and the selected subnetwork; computing a total voice quality metric of the communication route based on the vocoder impairment, the RF link impairment, the subnetwork impairment, and the delay impairment; and determining whether and when to make a handoff based on the total voice quality metric of the communication route.
2. The method of claim 1 , wherein computing the vocoder impairment comprises determining a baseline quality level of the vocoder and an impairment factor of the vocoder due to either bit errors or packet losses.
3. The method of claim 1 , wherein computing the RF link impairment comprises estimating data loss incurred through the RF link and determining an impairment factor of the RF link due to bit errors or packet losses.
4. The method of claim 1 , wherein computing the subnetwork impairment comprises determining an impairment factor due to bit errors or packet losses for each link in the subnetwork.
5. The method of claim 1 , wherein the delay impairment is computed using one or more equations of the International Telecommunication Union (ITU) E-model.
6. The method of claim 1 , wherein determining whether and when to make a handoff comprises making a handoff between a first communication route having a first total voice quality metric beneath a threshold level and a second communication route having a second total voice quality metric above the threshold level.
7. The method of claim 1 , wherein determining whether and when to make a handoff comprises making a handoff to a second communication route when a first communication route has a total voice quality metric which is lower than a second total voice quality metric of the second communication route.
8. The method of claim 1 , wherein determining whether and when to make a handoff comprises making a handoff based on a cost of a current communication route and costs of one or more other communication routes in the network.
9. The method of claim 8 , wherein making the handoff based on the cost is manageable by a user in the network.
10. The method of claim 1 , comprising storing the computed total voice quality metric as a function of a spatial location of a communication device in the network, and wherein determining whether and when to make the handoff comprises predicting a likely handoff based on the stored total voice quality metric and conducting a preemptive handoff based on the likely handoff prediction.