A method of transmitting scheduling information by a wireless communication device and a wireless communication device in accordance with embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which:
In
In
Such wireless communication systems are well known in the art, and therefore the specifics of such systems will not be described in detail, apart from where appropriate for the understanding of the disclosure as described herein.
The UE 200 comprises, among other entities well known by those having ordinary skill in the art, a control entity 210 in the form of an exemplary radio resource control (RRC) processing entity for configuration and control. The control processing entity 210 is communicably coupled to a receiving entity 220 and to a transmitting entity 230 and to a Man Machine Interface (MMI) 231, including elements such as a key pad, microphone, speaker, display screen, for providing an interface between the UE 200 and the user of the UE. The receiving entity 220 and the transmitting entity 230 are shown in
Under the control of the control processing entity 210, scheduling information (SI) is compiled or generated by the scheduling information generation entity 242, which communicates with the MAC-e PDU generation entity 244. The MAC-e PDU generation entity 244 generates the enhanced MAC PDU (MAC-e PDU) for transmission by the UE via the transmitting entity 230. MAC-e PDUs are transmitted by the UE to the Node B on an Enhanced Dedicated Channel (E-DCH) which is in turn carried by the Enhanced Dedicated Physical Data Channel (E-DPDCH). The MAC-e PDU generation entity 244 includes the generated scheduling information in a MAC-e PDU. The scheduling information SI may be sent alone in the MAC-e PDU or multiplexed with data and sent in the MAC-e PDU. In an exemplary embodiment, the presence of scheduling information is indicated in a header of the MAC-e PDU using one or more bits. For example the MAC protocol specification TS 25.321, V6.9.0 specifies that the field DDI of the PDU header indicates that scheduling information is included in the MAC-e PDU.
An exemplary format for scheduling information sent by the UE 200 to a serving Node B is shown in
At step, 500 the transmitting entity 230 of the UE 200 transmits to the network (e.g. serving Node B 112) scheduling information generated by the scheduling information generation entity 242 relating to the current resource requirement of the UE 200. At step 510, the UE 200 (for example, by means of the control processing entity 210 of the UE 200) determines whether the scheduling information has been received at the serving Node B 112 and if it has been received, new scheduling information relating to the new or subsequent resource requirement of the UE 200 is transmitted to the network, step 512. The UE 200 determines that the scheduling information has been received at the Node B 112 when an ACK acknowledgement message from the Node B 112 is received at the UE 200. If the scheduling information has not been received correctly at the network (i.e. when no ACK acknowledgement message has been received at the UE 200 and a re-transmission timer which counts the predetermined number of retransmissions has expired or if a NACK acknowledgement message has been received by the UE 200), the process moves to step 514 where it is determined (for example, by means of the control processing entity 210 of the UE 200) whether the scheduling information has been re-transmitted more than a maximum number of retransmission times, which is a predetermined number indicated in the HARQ profile for the UE which is previously signalled to the UE from the network. If the scheduling information has not been re-transmitted more than the predetermined number, the scheduling information is re-transmitted at step 516 and the flow continues with step 510. If the scheduling information has been re-transmitted more than the predetermined number, the process moves to step 512, and new scheduling information relating to the new current resource requirement of the UE 200 is transmitted to the network, Node B 112. The process then returns to step 510 to determine whether the new scheduling information has been received at the network and the process continues until an end (step 518), such as the UE being turned off.
As discussed above, previously a UE has been arranged to compile and transmit scheduling information to a serving Node B in response to a trigger event. The trigger event may be periodic trigger events (e.g. when a predetermined period counted by a periodic trigger timer expires periodically), and/or non-periodic trigger events, such as a change in the UE's buffer status, a change in the power available to the UE's (e.g. the UE's power headroom), a change in the cell serving the UE (including changing in the sector within the same serving cell), and/or a change in high priority data waiting in the UE's buffer.
In embodiments of the disclosure, for trigger events that comprise non-periodic trigger events such as a change in resource requirements of the UE and a change in the cell serving the UE (including changing in the sector within the same serving cell), the non-periodic trigger event is detected by the control processing entity 410 and the scheduling information is compiled or generated in response to a trigger event at any time in the process flow of
In other embodiments when the trigger events are generated periodically at predetermined periods, the scheduling information will not be compiled or generated nor transmitted in response to the periodic trigger event if any previous scheduling information is still being transmitted or re-transmitted to the network. Periodic trigger events are timed by a periodic trigger timer (not shown) in the UE 200 which is arranged to count a predetermined period. The periodic trigger timer (not shown) may be coupled to the control processing entity 210 and the MAC entity 240 or be part of the control processing entity 210. When the predetermined period expires, the transmission of the scheduling information is triggered under the control of the control processing entity 210. The periodic trigger timer is restarted when the transmission of the scheduling information is triggered. When previous scheduling information is still to be transmitted or re-transmitted, the periodic trigger event will be ignored by the UE and no new scheduling information generated and transmitted. The periodic trigger timer will however still be restarted in response to a trigger event even if it is ignored. The periodic trigger event may occur at any point in the process flow of
In an alternative embodiment, scheduling information may be generated or compiled in response to a periodic trigger event but not transmitted until previously sent scheduling information has been received by the network (as indicated by an ACK message from the network) or has not been received at the network after a predetermined number of re-transmissions.
In effect, the method in accordance with the disclosure initiates the process of transmitting scheduling information by generating the scheduling information in response to a non-periodic trigger event but does not transmit the generated scheduling information to the network until previous scheduling information has been received by the network or the previous scheduling information has not been received at the network after a predetermined number or re-transmissions. In the event that multiple non-periodic trigger events occur whilst the previous scheduling information is still being re-transmitted to the network, multiple scheduling information will be generated and queued for later transmission once the previous scheduling information is no longer being retransmitted to the network. Furthermore, the method in accordance with the disclosure ignores periodic trigger events such that the scheduling information is not transmitted to the network in response to a periodic trigger event.
It will be appreciated that in some embodiments the trigger events can include periodic trigger events and the non-periodic trigger events, such as a change in the UE's buffer status, a change in the power available to the UE's (e.g. the UE's power headroom), a change in the cell serving the UE (including changing in the sector within the same serving cell), and/or a change in high priority data waiting in the UE's buffer.
In the case of a change in the serving cell, the UE 200 receives notification which originates from the RNC 110, of a change in the cell serving the UE 200. The notification is received by the UE 200 at the receiving entity 220 and is communicated to the RRC processing entity 210. In 3G UMTS applications, the notification received by the UE is embodied as a RRC message containing an E-DCH allocation. The E-DCH allocation comprises the ID of the new serving cell and also other configuration information. The scheduling information is sent in response to the notification after allocation of a new E-DCH to provide the new serving cell all the information needed to schedule the UE. In some embodiments, the scheduling information is transmitted to the new serving cell only when the UE has buffered data for transmission on a channel for which scheduling information must be sent. In these embodiments, the transmission of the scheduling information is thus conditioned on the existence of buffered data for transmission.
In the case of a trigger event such as an UE buffer status change, highest priority or power headroom change, expiry of the periodic predetermined time limit, no notification is sent by the RNC 110 to the UE 200.
First scheduling information SI1, which is multiplexed with data in one MAC-e PDU, is transmitted from the UE to the serving Node B at 602. The first scheduling information SI1 is not received correctly at the serving Node B (e.g. Node B cannot decode SI1 due to errors in the received SI1) and in response, Node B sends a NACK to the UE for the first scheduling information SI1 at 604. As part of the HARQ mechanism, the first scheduling information SI1 is re-transmitted, at 606. The first re-transmission of the first scheduling information SI1 is not received correctly at the serving Node B and in response, Node B sends a NACK message to the UE for the first scheduling information SI1 at 608. At time 609, the 20 ms period counted by the periodic trigger timer expires but the UE ignores the trigger event and does not transmit a new scheduling information in response. However, the UE still restarts the periodic trigger timer. Subsequently, in response to the NACK received from the Node B for the first scheduling information SI1 at 608, the first scheduling information SI1 is re-transmitted to Node B for a second time, at 610. The second re-transmission of the first scheduling information SI1 is not received correctly at the serving Node B and in response, Node B sends a NACK message to the UE for the first scheduling information SI1 at 612. In response to the NACK received from the Node B for the first scheduling information SI1, the first scheduling information SI1 is re-transmitted to Node B for a third time, at 614. This time Node B correctly receives the first scheduling information SI1 and sends an ACK message to the UE for the first scheduling information SI1, at 616. Subsequently at 618, a Grant control signal according to the information sent in the first scheduling information SI1 is then sent by the Node B to the UE. At the expiry of the next 20 ms predetermined period, a new scheduling information SI2 is generated and transmitted by the UE to the Node B, at 620.
Since the second scheduling information SI2 is not sent to the serving Node B until a ACK message is received from the Node B for the first scheduling information SI1, the second scheduling information is not received by the Node B before the first scheduling information. This ensures that the scheduling information is not received and processed out of order with the result that the UE can be configured optimally for the most current data in its transmission buffer.
First scheduling information SI1, which is multiplexed with data in one MAC-e PDU, is transmitted from the UE to the serving Node B at 702. The first scheduling information SI1 is not received correctly at the serving Node B (e.g. Node B cannot decode SI1 due to errors in the received SI1) and in response, Node B sends a NACK to the UE for the first scheduling information SI1 at 704. As part of the HARQ mechanism, the first scheduling information SI1 is re-transmitted, at 706. The first re-transmission of the first scheduling information SI1 is not received correctly at the serving Node B and in response, Node B sends a NACK message to the UE for the first scheduling information SI1 at 708. At time 709, data having higher priority than the data currently in the transmit buffer of the UE arrives in the transmit buffer and represents a trigger event. In response, transmission of scheduling information is initiated and second scheduling information SI2 is compiled for the new state of the transmit buffer but the second scheduling information SI2 is not transmitted at this time since no ACK message has been received from the Node B for the first scheduling information SI1 nor has the maximum number of re-transmissions of the first scheduling information SI1 been reached. Subsequently, in response to the NACK received from the Node B for the first scheduling information SI1 at 708, the first scheduling information SI1 is re-transmitted to Node B for a second time, at 710. The second re-transmission of the first scheduling information SI1 is not received correctly at the serving Node B and in response, Node B sends a NACK message to the UE for the first scheduling information SI1 at 712. In response to the NACK received from the Node B for the first scheduling information SI1, the first scheduling information SI1 is re-transmitted to Node B for a third time, at 714. This time Node B correctly receives the first scheduling information SI1 and sends an ACK message to the UE for the first scheduling information SI1, at 716. Once an ACK message has been received for the first scheduling information SI1, the second scheduling information SI2 is transmitted by the UE to the Node B, at 718. Subsequently at 720, a Grant control signal according to the information sent in the first scheduling information SI1 is then sent by the Node B to the UE. The UE configures its resource allocation according to the Grant control signal for the first scheduling information SI1. At 722, the UE receives an ACK message from the Node B for the second scheduling information SI2. Subsequently at 724, a Grant control signal according to the information sent in the second scheduling information SI2 is then sent by the Node B to the UE. The UE configures its resource allocation according to the Grant control signal for the second scheduling information SI2.
As with the flow of
In summary, the method in accordance with the disclosure does not allow for scheduling information to be transmitted to the Node B until a previous scheduling information has been received by the Node B as indicated by an ACK message from the Node B or until the previous scheduling information has been re-transmitted a predetermined number of times. The transmission of the scheduling information may further be in response to a periodic or a non-periodic trigger event. The scheduling information may be generated in response to a non-periodic trigger event but is still not transmitted until a previous scheduling information has been received by the Node B as indicated by an ACK message from the Node B or until the previous scheduling information has been re-transmitted a predetermined number of times. In the case of a periodic trigger event, the trigger will be ignored, scheduling information will not be compiled, and the periodic trigger timer is restarted.
The method in accordance with the disclosure thus ensures that the scheduling information is processed by the Node B in the correct order (i.e. the order in which they were generated) so that the UE can be configured correctly to best handle the current data in the transmit buffer.
As discussed above, the method in accordance with the disclosure may be used with any type of trigger events, including periodic and/or non-periodic events.