Methods and apparatuses for user equipment-based enhancements of radio link control for multi-point wireless transmission
In aspects of the present disclosure, a user equipment receives inter-NodeB multi-point transmissions, and a multipoint aggregation component detects a gap in the sequence numbers, delays transmitting a not acknowledged signal (NAK) by starting a NAK delay timer, and transmits, by a transceiver, NAK for the gap in sequence numbers in response to the NAK delay timer expiring and detecting that the gap has not been filled during the delaying. If the Medium Access Control (MAC) entity as the respective NodeB identifies itself to the Radio Link Control (RLC), out-of-order delivery (skew) can eventually be distinguished from genuine data loss before the NAK delay timer expires based upon tracking the highest sequence numbers received. Adaptive NAK delay timer can be performed by monitoring skew duration.
1. A method for wireless communication, comprising:
receiving, by a user equipment, a plurality of data streams that together carry a data transmission, the plurality of data streams including a first data stream from a first cell and a second data stream from a second cell, the first data stream and the second data stream comprising Radio Link Control (RLC) Packet Data Units (PDUs) having respective sequence numbers of the data transmission;
detecting, at the user equipment, a gap in the sequence numbers of the RLC PDUs;
delaying, at the user equipment, transmitting a not acknowledged (NAK) for the gap in the sequence numbers of the RLC PDUs by starting a NAK delay timer in the user equipment upon detecting the gap;
determining, at the user equipment during a delay period after the NAK delay timer has started, whether the NAK delay timer has expired;
detecting, at the user equipment during the delay period, whether the gap has been filled, and
determining, at the user equipment during the delay period, whether each sequence number of the gap is lower than each of a highest sequence number of the first data stream and a highest sequence number of the second data stream before the NAK delay timer has expired, and
transmitting, by the user equipment, the NAK upon a determination of a first to occur of:
the user equipment determining that the NAK delay timer has expired and detecting that the gap has not been filled during the delay period; and
the user equipment determining that each sequence number of the gap is lower than each of the highest sequence number of the first data stream and the highest sequence number of the second data stream before the NAK delay timer has expired.
2. The method of claim 1 , further comprising identifying whether a selected RLC PDU was transmitted by a first Medium Access Control (MAC) entity of the first cell or a second MAC entity of the second cell.
3. The method of claim 1 , further comprising:
tracking, at the user equipment, a skew duration by detecting when the gap in the sequence numbers of the RLC PDUs is subsequently filled; and
adapting, at the user equipment, the NAK delay timer to correspond to the skew duration.
4. The method of claim 1 , wherein the instructions executable by the processor to detect a gap in the sequence numbers of the RLC PDUs comprises instructions executable by the processor to detect the gap in the sequence numbers of the RLC PDUs in a sequence number queue and the sequence number queue comprises a compilation of the sequence numbers from the first data stream and the sequence numbers from the second data stream.
5. The method of claim 1 , wherein the method is for a High Speed Download Packet Access (HSDPA) system.
6. The method of claim 1 , wherein the RLC PDUs have varying packet sizes.
7. The method of claim 1 , wherein the instructions further comprise instructions being executable by the processor to:
determine whether the gap comprises a new gap or an existing gap;
start a new NAK delay timer for the gap based on a determination that the gap comprises a new gap; and
transmit the NAK based on a determination that the gap comprises an existing gap where an existing NAK delay timer corresponding to the existing gap has expired.
8. At least one processor for wireless communication, comprising:
a first module for receiving, by a user equipment, a plurality of data streams that together carry a data transmission, the plurality of data streams including a first data stream from a first cell and a second data stream from a second cell, the first data stream and the second data stream comprising Radio Link Control (RLC) Packet Data Units (PDUs) having respective sequence numbers of the data transmission;
a second module for detecting, at the user equipment, a gap in the sequence numbers of the RLC PDUs;
a third module for delaying, at the user equipment, transmitting a not acknowledged (NAK) for the gap in the sequence numbers of the RLC PDUs by starting a NAK delay timer in the user equipment upon detecting the gap;
a fourth module for determining, at the user equipment during a delay period after the NAK delay timer has started, whether the NAK delay timer has expired;
a fifth module for detecting, at the user equipment during the delay period, whether the gap has been filled;
a sixth module for determining, at the user equipment during the delay period, whether each sequence number of the gap is lower than each of a highest sequence number of the first data stream and a highest sequence number of the second data stream before the NAK delay timer has expired; and
a seventh module for transmitting, by the user equipment, the NAK upon a determination of a first to occur of:
the user equipment determining that the NAK delay timer has expired and detecting that the gap has not been filled during the delay period; and
the user equipment determining that each sequence number of the gap is lower than each of the highest sequence number of the first data stream and the highest sequence number of the second data stream before the NAK delay timer has expired.
9. A non-transitory computer-readable medium storing computer-executable code, that when executed by a processor, causes a user equipment to:
receive a plurality of data streams that together carry a data transmission, the plurality of data streams including a first data stream from a first cell and a second data stream from a second cell, the first data stream and the second data stream comprising Radio Link Control (RLC) Packet Data Units (PDUs) having respective sequence numbers of the data transmission;
detect a gap in the sequence numbers of the RLC PDUs;
delay transmitting a not acknowledged (NAK) for the gap in the sequence numbers of the RLC PDUs by starting a NAK delay timer in the user equipment upon detecting the gap;
determine, during a delay period after the NAK delay timer has started, whether the NAK delay timer has expired;
detect, at the user equipment during the delay period, whether the gap has been filled;
determine, at the user equipment during the delay period, whether each sequence number of the gap is lower than each of a highest sequence number of the first data stream and a highest sequence number of the second data stream before the NAK delay timer has expired; and
transmit the NAK upon a determination of a first to occur of:
the user equipment determining that the NAK delay timer has expired and detecting that the gap has not been filled during the delay period; and
the user equipment determining that each sequence number of the gap is lower than each of the highest sequence number of the first data stream and the highest sequence number of the second data stream before the NAK delay timer has expired.
10. An apparatus for wireless communication, comprising:
means for receiving, by a user equipment, a plurality of data streams that together carry a data transmission, the plurality of data streams including a first data stream from a first cell and a second data stream from a second cell, the first data stream and the second data stream comprising Radio Link Control (RLC) Packet Data Units (PDUs) having respective sequence numbers of the data transmission;
means for detecting, at the user equipment, a gap in the sequence numbers of the RLC PDUs;
means for delaying, at the user equipment, transmitting a not acknowledged (NAK) for the gap in the sequence numbers of the RLC PDUs by starting a NAK delay timer in the user equipment upon detecting the gap;
means for determining, at the user equipment during a delay period after the NAK delay timer has started, whether the NAK delay timer has expired;
means for detecting, at the user equipment during the delay period, whether the gap has been filled;
means for determining, at the user equipment during the delay period, whether each sequence number of the gap is lower than each of a highest sequence number of the first data stream and a highest sequence number of the second data stream before the NAK delay timer has expired; and
means for transmitting, by the user equipment, the NAK upon a determination of a first to occur of:
the user equipment determining that the NAK delay timer has expired and detecting that the gap has not been filled during the delay period; and
the user equipment determining that each sequence number of the gap is lower than each of the highest sequence number of the first data stream and the highest sequence number of the second data stream before the NAK delay timer has expired.
11. An apparatus for wireless communication, comprising:
a processor; and
a memory in electronic communication with the processor, instructions stored in the memory being executable by the processor to;
receive, by a user equipment, a plurality of data streams that together carry a data transmission, the plurality of data streams including a first data stream from a first cell and a second data stream from a second cell, the first data stream and the second data stream comprising Radio Link Control (RLC) Packet Data Units (PDUs) having respective sequence numbers of the data transmission; and
detect, at the user equipment, a gap in the sequence numbers of the RLC PDUs;
delay, at the user equipment, transmitting a not acknowledged (NAK) for the gap in the sequence numbers of the RLC PDUs by starting a NAK delay timer in the user equipment upon detecting the gap;
determine, at the user equipment and during a delay period after the NAK delay timer has started, whether the NAK delay timer has expired;
detect, at the user equipment during the delay period, whether the gap has been filled;
determine, at the user equipment during the delay period, whether each sequence number of the gap is lower than each of a highest sequence number of the first data stream and a highest sequence number of the second data stream before the NAK delay timer has expired, and
transmit the NAK upon a determination of a first to occur of:
the user equipment determining that the NAK delay timer has expired and detecting that the gap has not been filled during the delaying; and
the user equipment determining that the gap is lower than each of the highest sequence number of the first data stream and the highest sequence number of the second data stream before the NAK delay timer has expired.
12. The apparatus of claim 11 , wherein the instructions further comprise instructions being executable by the processor to identify whether a selected RLC PDU was transmitted by a first MAC entity of the first cell or a second MAC entity of the second cell.
13. The apparatus of claim 11 , wherein the instructions further comprise instructions being executable by the processor to determine a skew duration when the gap in the sequence numbers of the RLC PDUs is subsequently filled, and instructions being executable by the processor to adapt the NAK delay timer in the user equipment to correspond to the skew duration.