A novel architecture for IEEE 802.16m subscriber station for joint power saving class management

IEEE 802.16m amendment is being drafted to meet the 4G network requirements as an extension to 802.16e-2005. In 802.16e, a Subscriber Station (SS) can have multiple connections to a Base Station (BS) for supporting different services simultaneously. SS negotiates sleep-mode with BS by exchange of management information for one or more connections per active Power Saving Class Identifier (PSC_ID) belonging to a Power Saving Class (PSC). However, after this negotiation, SS may not be able to switch to actual sleep-mode (low power operation) as connections belonging to other PSC_ID may be in the transmission or reception mode. Moreover, this causes an overhead of management messages exchanged between the SS and BS per PSC_ID that results in excess packet delay as well as wastage of power and bandwidth. In this paper, we propose a novel architecture referred as Sleep-Mode Manager Architecture to negotiate the sleep mode for the SS and to compute the sleep-mode per quality of service (QoS) class by aggregating the unavailability periods of all the active PSC_ID traffic. This architecture reduces the overhead of management messages, thereby conserving bandwidth and energy as well as supporting dynamic adaptation in sleep-mode parameters. Our simulation and analysis results reveal that the proposed architecture performs substantially better than the 802.16e standard and the relative performance improves with increasing number of active PSC_IDs which can be implemented in 802.16m. Furthermore, through analysis we find that the efficiency of device switching to sleep-mode improves from 7.1% in case of single PSC_ID to 35% in case of joint power class management for ten simultaneous connections. Simulation reveals that, the management message exchange overhead in case of proposed joint power saving class reduces to 1/5^th of that in case of individual PSC_ID management in case of four simultaneous PSC_IDs.