Conclusion

802.11e is based on over a decade of experience in designing WLAN protocols and was built from the ground up for real-world wireless conditions. 802.11e is backward compatible with 802.11-that is, non-802.11e terminals can receive QoS-enabled application streams.

This chapter described measures aimed at improving QoS in 802.11 networks. These wireless networks are potentially capable of delivering QoS comparable to the PSTN. It should be noted that the Regional Bell Operating Companies (RBOCs) have been losing phone lines to cell phone service providers at an alarming rate (for the RBOCs) over the last year. In fact, the RBOCs have recorded, percentage-wise, their first decline in lines in use since the Great Depression. Cell phone service is admittedly inferior in quality to that of the PSTN. The motivating factor for landline customers to drop their service from the RBOC is the convenience offered by the cell phone as well as certain price advantages (free long distance in off-peak hours). The point here is that, ultimately, the QoS of the PSTN is not an absolute requirement for consumers. Consumers, in the case of cell phones, have traded off QoS for convenience and price. The PSTN is doomed if it must compete with 802.11 in that 802.11, using 802.11e, potentially delivers a comparable QoS in both voice and data services while offering data rates up to 11 Mbps (compared with most Digital Subscriber Line [DSL] plans at 256 Kbps). Given that consumers will trade QoS for convenience and price, as witnessed by the loss of lines to cell phone service providers, it is not hard to imagine they would, trade off the PSTN for the convenience of greater bandwidth and the wider range of services (video on demand, videoconferencing, and so on) available with that greater bandwidth even if wireless QoS on the subscriber's telephone service (the primary component of the PSTN) was not as good as that of the PSTN.