Practical measurement-based session admission control for Wi-Fi LAN systems
View Patent ↗A communication system is provided that can control which communication sessions with mobile devices are admitted to a wireless access point. The admission decisions are based on actual measurements of radio frequency (RF) utilization. The RF utilization is determined on a per access class basis. Access classes may be defined by protocol but are, generally, voice, video and data. Thus, the system provides the ability to determine admissions that allows for the incorporation of factors including collisions, the distance from the access point to which a mobile device is communicating, and other factors.
1. A method for determining whether to admit a new communication session at a wireless access point, the method comprising:
a processor measuring an over-the-air utilization at the wireless access point, wherein the over-the-air utilization is measured by a radio frequency (RF) utilization for one or more radios associated with the wireless access point and wherein the wireless access point measures the RF utilization, wherein measuring radio frequency (RF) utilization comprises:
the processor measuring a data rate (PHY) for one or more frames, wherein PHY is a measurement of the data rate for a physical layer of the wireless access point;
based on a frame size and the PHY, the processor determining a transmission time for the one or more frames, wherein the transmission time is determined by dividing the frame size by the PHY;
the processor adding overhead time to the transmission time;
the processor summing the overhead and transmission times for at least two associated communication sessions to determine the data air time; and
the processor dividing the data air time by an elapsed time to determine the RF utilization;
the processor receiving a request for the new communication session;
the processor determining an amount of bandwidth based on the measured over-the-air utilization and an amount of bandwidth requested for the new communication session;
based on the bandwidth for the measured over-the-air utilization and the bandwidth requested for the new communication session, the processor determining whether to admit the new communication session; and
if there is sufficient available bandwidth for the new communication session, the processor admitting the new communication session at the wireless access point.
2. The method as defined in claim 1 , wherein the data air time is for an access class.
3. The method as defined in claim 2 , wherein there is two or more access classes each with a different data air time.
4. The method as defined in claim 2 , wherein the access class includes at least two of a group comprising video, voice, and data.
5. The method as defined in claim 2 , wherein the access class has a predetermined bandwidth allotment.
6. A non-transitory computer readable medium, stored on a tangible medium, having stored thereon instructions that cause a computing system to execute a method for determining whether to admit a communication session at a wireless access point, the instructions comprising:
instructions to receive a summation of a measured radio frequency (RF) utilization and a requested bandwidth for a requested communication session between the wireless access point and a mobile device;
instructions to compare the summation to an allocated bandwidth, wherein the allocated bandwidth is allocated for an access class;
if the summation is more than the allocated bandwidth, instructions to deny the requested communication session; and
if the summation is less than the allocated bandwidth, instructions to admit the requested communication session, wherein the requested communication session is for a requested access class and wherein the comparison of the summation to the allocated bandwidth is for the requested access class, the instructions further comprising:
instructions to determine if there is bandwidth to borrow from a second access class;
if there is bandwidth to borrow from a second access class, allocate the borrowed bandwidth to the requested communication and admit the requested communication session; and
if there is no bandwidth to borrow from a second access class, deny the requested communication session.
7. The computer readable medium as defined in claim 6 , wherein the borrowed bandwidth is borrowed for a limited time.
8. The computer readable medium as defined in claim 6 , further comprising instructions to reserve bandwidth for inter-access point transfers of communication sessions, wherein the reserved bandwidth is part of the summation.
9. The computer readable medium as defined in claim 6 , further comprising instructions to reserve bandwidth for emergency communication sessions, wherein the reserved bandwidth is part of the summation.
10. A communication system comprising:
two or more wireless access points, the two or more wireless access points configured to measure an over-the-air utilization that is measured by a radio frequency (RF) utilization for one or more radios associated with the two or more wireless access points, and configured to receive a request for a communication session from a mobile device; and
a control server in communication with the two or more wireless access points, the control server configured to receive the RF utilization and the request for the communication session and configured to determine from the RF utilization and the request for the communication session whether the requested communication session should be admitted by one of the two or more access points, wherein the control server comprises:
a new flow estimator configured to determine a new bandwidth amount that will be used if the requested communication session is admitted; and
an admission decision module in communication with the new flow estimator, the admission decision module configured to compare the new bandwidth amount to an allotment of bandwidth and configured, based on the comparison, to send an admit signal to one of the wireless access points to admit the requested communication session.
11. The communication system as defined in claim 10 , wherein each of the two or more access points comprise:
a traffic measurements module configured to measure the RF utilization; and
a signal interface module configured to receive the request for the communication session.
12. The communication system as defined in claim 10 , wherein the new bandwidth amount is determined by adding the measured RF utilization from the traffic measurements module with a requested bandwidth received from the mobile device by the signal interface.
13. The communication system as defined in claim 10 , wherein, if the communication session is admitted, the RF utilization is deemed to be full and the RF utilization is attenuated to the measured RF utilization over a predetermined period of time.
14. The communication system as defined in claim 13 , wherein the admission decision module is configured to allot borrowed bandwidth from a second access class to the communication session and is configured to admit the communication session with the borrowed bandwidth.