10 Non-scheduled transmissions

25.3193GPPEnhanced uplinkOverall descriptionStage 2TS

When non-scheduled transmission is configured by the SRNC, the UE is allowed to send E-DCH data at any time, up to a configured number of bits, without receiving any scheduling command from the Node B. Thus, signalling overhead and scheduling delay are minimized.

Typical examples of data that may use non-scheduled transmission are the SRBs and GBR services.

For FDD and 1.28Mcps TDD, in CELL_FACH state and Idle mode, non-scheduled transmission is not supported.

Non-scheduled transmissions have the following characteristics:

– Non-scheduled transmissions are defined per MAC-d flow;

– The resource for non-scheduled transmission is given by the SRNC in terms of maximum number of bits that can be included in a MAC-e / MAC-i PDU, and is called non-scheduled grant;

– Scheduled logical channels cannot use a non-scheduled grant.

– For TDD a non scheduled grant is defined by:

– The codes and timeslots available for transmission in TTIs designated for unscheduled use

– The frames or sub-frame designated for unscheduled use (specified by means of start frame number, repetition period and repetition length)

For FDD:

– UTRAN can restrict a non-scheduled MAC-d flow to use a limited number of HARQ processes in case of 2ms TTI;

– UTRAN can reserve some HARQ processes for non-scheduled transmission (i.e. scheduled data cannot be sent using these processes, they are considered disabled) in case of 2ms TTI;

– Reserving certain HARQ processes for non-scheduled transmission and restricting non-scheduled transmission to specific HARQ processes are scheduling mechanisms under the control of the serving cell Node B; Serving cell Node B signals the applicability of allocated resources for non-scheduled/scheduled transmission to HARQ processes according to the restriction/reservation decision to S-RNC, which informs other Node Bs in the E-DCH active set.

– Multiple non-scheduled MAC-d flows may be configured in parallel by the SRNC;

– The UE is then allowed to transmit non-scheduled transmissions up to the sum of the non-scheduled grant if multiplexed in the same TTI;

– For TDD, HARQ process identifiers 0 – 3 are reserved for scheduled transmissions and HARQ process identifiers 4 – 7 are reserved for non-scheduled transmissions;

– For FDD, Scheduled grants will be considered on top of non-scheduled transmissions;

– Logical channels mapped on a non-scheduled MAC-d flow cannot transmit data using a Scheduling Grant;

– Logical channels mapped on a non-scheduled MAC-d flow can only transmit up to the non-scheduled grant configured for that MAC-d flow;

– The multiplexing list restricting the set of HARQ profiles that can be used by a given logical channel will apply both for scheduled and non-scheduled logical channels;

– Logical channels will be served in the order of their priorities until the non-scheduled grant and scheduled grants are exhausted, or the maximum transmit power is reached;

– When multiple logical channels are assigned the highest priority, the selection of the HARQ profile for these logical channels is not specified.