Shared medium

Abstract: A novel and useful media access control (MAC) protocol that is intended for use over noisy shared media channels. The MAC protocol provides layer 2 functionality over a network using a shared medium including a backoff mechanism for CSMA.CA channel access, link addressing that reduces the overhead of long MAC addresses, a flooding scheme having controlled exposure for broadcast transmissions, multicast transmissions using selective ACKs, implementation of traffic prioritization using an adaptive backoff scheme, a second layer repeater establishment process and multi-packet transport for short packets and fragmentation for long packet transport.

Abstract: Wireless network data consumption is experiencing drastic increases due to growing demands of mobile services and applications. Deployed networks using Radio Frequency (RF) communications are characterized by a shared medium, limited available spectrum and limited ability to scale with increasing demand. Directional communications, including Visible Light Communications (VLC), can limit contention in controlled environments and provide scalability through spatial reuse of the medium. This solution can provide massive aggregate data capacity in indoor scenarios if properly distributed. In this paper we propose an indoor hybrid system that integrates WiFi and VLC luminaries. Our system utilizes (i) broadcast VLC channels to supplement RF communications and (ii) a handover mechanism between WiFi and VLC to dynamically distribute resources and optimize system throughput. This approach offers the bandwidth density benefits of VLC, provides a non-intrusive RF back-channel, maintains compatibility with conventional RF devices, and demonstrates excellent scalability. Analytical and simulation results show improvements in aggregate performance (i.e., throughput and delay) of the hybrid, when compared to either system acting alone.

Abstract: Techniques for MAC processing for efficient use of high throughput systems that is backward compatible with various types of legacy systems are disclosed. In one aspect a first signal is transmitted according to a legacy transmission format to reserve a portion of a shared medium, and communication according to a second transmission format transpires during the reserved portion. In another aspect, a communication device may contend for access on a legacy system, and then communicate according to a new class communication protocol with one or more remote communication devices during the access period. In another aspect, a device may request access to a shared medium according to a legacy protocol, and, upon grant of access, the device may communicate with or facilitate communication between one or more remote stations according to a new protocol.

Abstract: A method and system are disclosed for enabling point-to-point and multicast communication in a network using three types of communication channels, namely, one or more upstream payload channels, one or more upstream control channels and one or more downstream channels. At least the upstream control and upstream payload channels can carry bitstreams simultaneously; a bitstream may be simultaneously carried on the upstream control and upstream payload channels of a shared medium during overlapping periods of time. Each channel illustratively is divided into slots or mini-slots. Each upstream payload channel is assigned for carrying upstream directed payload bitstreams from stations to a central controller. Each upstream control channel is assigned for carrying upstream directed control bitstreams, such as reservation request bitstreams requesting reservation of time slots of the upstream payload channel, from the stations to the central controller. At least one downstream channel is assigned for carrying at least downstream directed control bitstreams, such as bitstreams containing acknowledgments, collision, status of reservation request, and also containing indications of assigned slots in the upstream payload channel, from the central controller to the stations. The downstream channel may also illustratively carry payload bitstreams.