Base stations and methods for receiving transmissions on an enhanced random access channel
Example base stations and methods for receiving transmissions on an enhanced random access channel (RACH) are disclosed herein. An example method for receiving transmissions on an enhanced RACH from a device such that an initial access burst is received in a single time slot from the device involves receiving the initial access burst from the device on the enhanced RACH. The initial access burst is sent by the device using a timing advance determined at the device. The initial access burst includes at least one of an identifier or user data. The enhanced RACH is a contention-based uplink-only channel requiring use of timing advances for transmissions thereon.
1. A method for receiving transmissions on an uplink contention-based random-access channel (RACH) from a device in a time-division multiple access (TDMA) communication system, the method comprising:
transmitting by a base station, a notification of the uplink contention-based RACH, the notification including an identification of time-slots of TDMA frames that comprise the uplink contention-based RACH;
transmitting, by the base station, a shortened identifier to the device, the shortened identifier uniquely identifying the device within a cell; and
when no uplink bandwidth has been allocated for data transmission by the device, receiving, at the base station, an initial access burst from the device on the uplink contention-based RACH, the initial access burst including user traffic data and the shortened identifier, the user traffic data to be sent by the base station to a network destination different than the base station, the initial access burst sent by the device using a known timing advance greater than zero and determined at the device prior to a transmission of the initial access burst, wherein the initial access burst is transmitted at a time determined autonomously by the device in response to an upper level layer of the device requesting to send the user traffic data to the network destination when the device has no assigned resources.
2. The method of claim 1 wherein the initial access burst further includes the network destination.
3. The method of claim 2
wherein the method further comprises associating additional information with the user traffic data for forwarding to the network destination; and
wherein either the base station or a serving general packet radio service (GPRS) support node (SGSN) associates the additional information with the user traffic data for forwarding to the network destination.
4. The method of claim 1 further comprising:
associating the user traffic data received in the initial access burst with a network destination address based on an identity of the device; and
forwarding the user traffic data with the network destination address and the identity of the device to the network destination.
5. The method of claim 1 wherein prior to receiving the initial access burst, the method further comprises:
receiving a full-length identifier of the device; and
providing the shortened identifier to the device based on the full-length identifier,
wherein the shortened identifier is for use by the base station to distinguish between transmissions on the uplink contention-based RACH from devices with uplink contention-based RACH capability within the cell.
6. The method of claim 5 wherein the full-length identifier comprises an international mobile subscriber identity (IMSI), a temporary logical link identifier (TLLI) identifier or a temporary mobile subscriber identity (TMSI) of the device.
7. The method of claim 1 wherein the initial access burst further includes at least one of information about a requested data channel, information about capabilities of the device, or information identifying the device other than the shortened identifier.
8. The method of claim 1 ,
wherein the notification includes parameters defining the uplink contention-based RACH for initial access transmissions.
9. The method of claim 1 wherein the uplink contention-based RACH is a secondary RACH,
wherein a primary RACH is provided by the base station for receipt of access request messages from devices requesting assignment of a channel resource,
wherein when a timing advance is unknown, devices with uplink contention-based RACH capability are to use the primary RACH for transmitting access request messages for an assignment of a channel resource for a subsequent transmission of data and are to refrain from transmitting initial access bursts on the uplink contention-based RACH.
10. A non-transitory computer readable storage medium having instructions stored thereon that, when executed, cause a base station in a time-division multiple access (TDMA) communication system to perform operations comprising:
transmitting a notification of an uplink contention-based random-access channel (RACH), the notification including an identification of time-slots of TDMA frames that comprise the uplink contention-based RACH;
transmitting a shortened identifier to a device, the shortened identifier uniquely identifying the device within a cell; and
when no uplink bandwidth has been allocated for data transmission by the device, receiving, at the base station, an initial access burst from the device on the uplink contention-based RACH, the initial access burst including user traffic data and the shortened identifier, the user traffic data to be sent by the base station to a network destination different than the base station, the initial access burst sent by the device using a known timing advance greater than zero and determined at the device prior to a transmission of the initial access burst, wherein the initial access burst is transmitted at a time determined autonomously by the device in response to an upper level layer of the device requesting to send the user traffic data to the network destination when the device has no assigned resources.
11. A base station in a time-division multiple access (TDMA) communication system, the base station comprising:
a memory; and
at least one hardware processor communicatively coupled with the memory and configured to:
transmit a notification of an uplink contention-based random-access channel (RACH), the notification including an identification of time-slots of TDMA frames that comprise the uplink contention-based RACH;
transmit a shortened identifier to a device, the shortened identifier uniquely identifying the device within a cell; and
when no uplink bandwidth has been allocated for data transmission by the device, receive, at the base station, an initial access burst from the device on the uplink contention-based RACH, the initial access burst including user traffic data and the shortened identifier, the user traffic data to be sent by the base station to a network destination different than the base station, the initial access burst sent by the device using a known timing advance greater than zero and determined at the device prior to a transmission of the initial access burst, wherein the initial access burst is transmitted at a time determined autonomously by the device in response to an upper level layer of the device requesting to send the user traffic data to the network destination when the device has no assigned resources.
12. The base station of claim 11 wherein the initial access burst further includes the network destination, and
wherein the at least one hardware processor is further configured to associate additional information with the user traffic data for forwarding to the network destination.
13. The base station of claim 11 wherein the at least one hardware processor is further configured to:
associate the user traffic data received in the initial access burst with a network destination address based on an identity of the device; and
forward the user traffic data with the network destination address and the identity of the device to the network destination.
14. The base station of claim 11 ,
wherein the notification includes parameters defining the uplink contention-based RACH for initial access transmissions,
wherein the uplink contention-based RACH is a secondary RACH,
wherein a primary RACH is provided by the base station for receipt of access request messages from devices requesting assignment of a channel resource,
wherein when a timing advance is unknown, devices with uplink contention-based RACH capability are to use the uplink contention-based RACH for transmitting access request messages for an assignment of a channel resource for a subsequent transmission of data and are to refrain from transmitting initial access bursts on the uplink contention-based RACH.