The paper introduces the application of IEEE 802.11e to the delivery of high bandwidth multimedia streams. The architecture for a QoS enabled MAC is described along with an efficient scheduling algorithm, which, when deployed at the AP, is able to serve QoS sensitive streams, while making efficient use of the channel bandwidth. The 802.11e MAC is simulated using OPNET and the performance of both the EDCA (enhanced distributed channel access) and the HCCA (HCF controlled channel access) mechanisms is studied under various scenarios. The results illustrate that HCCA when used in conjunction with the QoS scheduler satisfies the requirements of AV and speech applications.

This correspondence describes modified QORC (MQORC) modulation. The power spectral density of MQORC is shown to take on the form of the product of the QPSK and SFSK spectra, which attains good spectral characteristics. We show that the bandpass hard-limited staggered MQORC tends to keep its sidelobes suppressed, and therefore, its sidelobes drop off faster compared to staggered QORC.