Media access control (mac) for an active rfid system

A system of radio frequency communication between Readers and Tags, the system comprising;

• (a) at least one tag Reader;
• (b) a plurality of Tags deployed in a region in which at least some of the Tags are in radio communication with said tag Reader, at least some tags are in radio communication with other Tags in said plurality of Tags and each Tag in the plurality of Tags is associated with a unique tag ID, and
• (c) a Media Access Control protocol according to which:
• said tag Reader is configured to send and receive radio communications to and from at least some of said plurality of Tags,
• said plurality of Tags are configured to send and receive radio communications to and from said tag Reader and other Tags in said plurality of Tags, wherein the plurality of Tags are assigned a pseudo-random ID based on the unique tag ID and a hash function and the plurality of Tags are divided into one or more groups based at least on one or more parts of the pseudo-random ID, and
• said Media Access Control protocol is configured to control said radio communications between said tag Reader and said plurality of Tags, such that said Media Access Control protocol uses a combination of a session ID, acknowledgements and use of other tags as relays to achieve high reliability of radio communication, in broadcast, multicast and unicast modes.

A system of radio frequency communication between Readers and Tags, the system comprising;

• (a) at least one tag Reader;
• (b) a plurality of Tags deployed in a region in which at least some of the Tags are in radio communication with said tag Reader, and wherein at least some tags are in radio communication with other Tags in said plurality of Tags, and each Tag in the plurality of Tags is associated with a unique tag ID;
• and
• (c) a Media Access Control protocol according to which:
• said tag Reader is configured to send and receive radio communications to and from at least some of said plurality of Tags,
• said plurality of Tags are configured to send and receive radio communications to and from said tag Reader and other Tags in said plurality of Tags, and
• said Media Access Control protocol is configured to control said radio communication between said tag Reader and said plurality of Tags, wherein the plurality of Tags are assigned a pseudo-random ID based on the unique to ID and a hash function and the plurality of Tags are divided into one or more groups based at least on one or more parts of the pseudo-random ID;
• and
• wherein said Media Access Control protocol includes tag reply parameters in each said radio communication so as to enable tags to respond to said tag Reader in a manner that is compatible with that tag Reader's capabilities.

A system of radio frequency communication between Readers and Tags, the system comprising;

• (a) at least one tag Reader;
• (b) a plurality of Tags deployed in a region in which at least some of the Tags are in radio communication with said tag Reader, and each Tag in the plurality of Tags is associated with a unique tag ID, and
• (c) a Media Access Control protocol according to which:
• said tag Reader is configured to send and receive radio communications to and from at least some of said plurality of Tags,
• said plurality of Tags are configured to send and receive radio communications to and from said tag Reader, wherein the plurality of Tags are assigned a pseudo-random ID based on the unique tag ID and a hash function and the plurality of Tags are divided into one or more groups based at least on one or more parts of the pseudo-random ID, and
• said Media Access Control protocol is configured to control said radio communication between said tag Reader and said plurality of Tags;
• wherein said radio communication includes an indication of a payload start point, and each generation of tag Readers and/or Tags is configured to decode that portion of said Media Access Control protocol with which it is familiar, ignores that portion of said Media Access Control protocol with which it is unfamiliar, and jumps to said payload start point, allowing tag Readers to efficiently communicate with a mixture of tag generations and/or tag versions.

A system of radio frequency communication between Readers and Tags, the system comprising;

• (a) at least one tag Reader;
• (b) a plurality of Tags deployed in a region in which at least some of the Tags are in radio communication with said tag Reader, at least some tags are in radio communication with other Tags in said plurality of Tags, and each Tag in the plurality of Tags is associated with a unique tag ID;
• and
• (c) a Media Access Control protocol according to which:
• said tag Reader is configured to send and receive radio communication to and from at least some of said plurality of Tags,
• said plurality of Tags are configured to send and receive radio communication to and from said tag Reader and other Tags in said plurality of Tags, wherein the plurality of Tags are assigned a pseudo-random ID based on the unique tag ID and a hash function and the plurality of Tags are divided into one or more groups based at least on one or more parts of the pseudo-random ID,
• and said Media Access Control protocol is configured to control said radio communication between said tag Reader and said plurality of Tags;
• wherein said radio communication includes a block of variable length, wherein a first generation Tags is configured to forward said block without modification, and a second generation tag Reader and/or Tag is configured to decode and modify said block as needed.