Adapter implementation between convergence and WIMAX specific lower layers

Several environmental phenomena affect the propagation of wireless communication signals, leading to time-varying changes in channel conditions and inefficient use of network resources. In order to mitigate these undesired effects, adaptation is applied at various hierarchical levels of the wireless network. An adapter module that retrieves the necessary information for adaptation enables these adaptation processes. Also, there is reason for the adapter to have control of and management access to hardware (HW), to serve the adaptive triggering mechanisms. To allow such functionality, the adapter needs to have the relevant access to HW-specific layers. In this master's thesis, preliminary versions of two optional adapter solutions were designed and implemented. A simple network management protocol (SNMP) client module was implemented in Linux user-space to allow the horizontal control and management actions. In addition, a modular Linux kernel-space network device driver was implemented to allow direct HW interactions in the data link layer (DLL) when suitable access to the hardware is available. A combination of an SNMP client and network driver was implemented for subscriber station (SS) and customer premises equipment (CPE) systems. For access service network gateway (ASN-GW) and network control system (NCS), the SNMP client was implemented. The adapter solutions were implemented using American National Standards Institute C (ANSI C). The usability and performance limits of the adapter solutions were measured via relevant performance evaluations. The performance of SNMP requests was evaluated for both wireless WiMAX 16d link and Ethernet link. The performance of adapter interfaces was evaluated using the implemented user-space and kernel-space stub modules, because of the lack of real co-operating modules. The measured round-trip time for an SNMP GET request was 6~ms for Ethernet link and 53~ms for wireless WiMAX 16d link. The round trip for an SNMP GET request was 83~ms in the worst case. Slightly longer round-trip times are assumed for SNMP SET requests due to database write operation. Thus, when the general requirement for the adaptation cycle is from 500 to 1000~ms in a wide range of adaptive processes, those measurements and the more detailed results gathered from the evaluations imply that both adapter solutions are applicable for their planned use.