This paper considers the MAC layer in General Packet Radio Service (GPRS) system. We present the MAC procedures used to enable multiple mobile stations to share a common transmission medium that may contains many radio physical channels. This layer makes use of slotted ALOHA protocol combined with a specific retransmission mechanism in order to establish the physical connection. The access pers...

We consider a wireless ad hoc network with random access channel. We present a model that takes into account topology, routing, random access in MAC layer, and forwarding probability. In this paper, we focus on drawing benefit from the interaction of the MAC (governed by IEEE 802.11 or slotted Aloha) and routing by defining a new cross-layer scheme for routing based on the limit number of retra...

In beacon-enabled mode, IEEE 802.15.4 is ruled by the slotted CSMA/CA Medium Access Control (MAC) protocol. The standard slotted CSMA/CA mechanism does not provide any means of differentiated services to improve the quality of service for timecritical events (such as alarms, time slot reservation, PAN management messages etc.). In this paper, we present and discuss practical service differentia...