A Linux Kernel Based Implementation of 802.11e HCCA

[...] The objective of this thesis is to follow a similar approach to introduce the 802.11e controlled access mechanism, HCCA, over the 802.11 MAC layer (focusing on the 802.11b [9] amendment, which raises the maximum transmission rate of 802.11) through the realization of a Linux kernel module, called Host HCF.
In Chapter 2 we discuss Linux Kernel Development : we explain the limitations and issues related to kernel development and the main concepts that a kernel developer must know. Then, we describe some important topics such as concurrency and locking and kernel debugging techniques.
In Chapter 3 we get in touch with the concept of quality of service and with the 802.11e standard: we discuss what is QoS and what are the parameters that are used to define QoS requirements and we describe the DiffServ and IntServ QoS models. Then we discuss the 802.11 DCF and PCF channel access mechanisms, in order to put in evidence the enhancements of EDCA and HCCA and later we examine into the details of the Hybrid Coordination Function (HCF): we describe how EDCA and HCCA work, discussing traffic specifications, QoS information signaling and the connection admission control procedures, which are fundamental for granting QoS. We conclude the chapter with a discussion on the 802.11e Sample Scheduler: the HCCA scheduler is the component that determines how the hybrid coordinator polls the stations of the QoS BSS and 802.11e do not impose the utilization of a particular scheduler. 802.11e just suggests a simple implementation, called Sample Scheduler. This makes the implementation of the scheduler one of the main issues on which the research on HCCA is focused.
In Chapter 4 we discuss our project, Host HCF: we describe the general architecture of the system and then we go on with the implementation details. We explain what we implemented of 802.11e and how we solved the issues related to kernel programming that we faced during the development.
We conclude the chapter with the description of our HCCA scheduler, called Basic Scheduler, which has been developed with the purpose of granting QoS to interactive voice streams, to preserve them from being damaged by best effort traffic.
Then, in Chapter 5 we discuss the tests we made with Host HCF to justify some of the implementation choices we made, to describe the behavior of Host HCF in different contexts and to show that it is able to preserve the quality of VoIP calls even in presence of high-load best effort traffic streams.