The present application relates generally to efficient adaptation of (semi) persistent scheduling in radio networks.
Many services for which data is to be transferred over radio networks generate data in a periodic fashion. For example voice services generate packets at intervals of typically 20 milliseconds. To facilitate the transfer of this data without having to schedule a radio resource allocation for each individual packet, radio schedulers typically facilitate persistent or semi-persistent allocations, which provide a plurality of periodically occurring resources, wherein the difference between persistent and semi-persistent allocations generally exist in that persistent allocations provide unlimited periodically occurring resources until the persistent allocation is explicitly or implicitly canceled and semi-persistent allocations provide a limited number of of periodically occurring resources, e.g., upon voice activity. The invention as disclosed in the present application may be be equally applied to persistent and semi-persistent scheduling, which for brevity of notation will infra collectively be referred to as persistent scheduling or persistent allocation.
Updating of an active persistent allocation is generally performed only by full replacement of the persistent allocation, often requiring first terminating the active allocation.
Various aspects of examples of the invention are set out in the claims.
According to a first aspect of the present invention, there is disclosed an apparatus, computer program product and method for transmitting a persistent resource allocation in accordance with a periodicity to a user equipment; determining at least one resource-shift of a resource of the persistent resource allocation; transmitting an indication of the at least one resource-shift to the user equipment; and transmitting or receiving data to or from the user equipment in accordance with the resource-shifted persistent resource allocation.
According to a second aspect of the present invention, there is disclosed an apparatus, computer program product and method for receiving a persistent resource allocation in accordance with a periodicity from a network node; receiving an indication of at least one resource-shift of a resource of the persistent resource allocation; adapting at least one resource of the persistent resource allocation in accordance with the at least resource-shift; and transmitting or receiving data to or from a network node in accordance with the adapted persistent resource allocation.
For a more complete understanding of example embodiments of the present invention, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:
Many services for which data is to be transferred over radio networks generate data in a periodic fashion. In general, and particularly for latency critical and ultra-reliable services, it is desirable not to restrict the feasible periodicity in accordance with the numerology of any radio interface over which the service is to be carried. Therefore, it may be desirable to support any arbitrary periodicity irrespective of a unit of resource allocation available on the radio interface. In addition, it is desirable to minimize the control signaling overhead on the radio interface to support such an arbitrary periodicy, such that it is preferable to avoid having to signal a new persistent resource allocation. Embodiments of the present invention as disclosed herein provide for the support by a radio interface of any periodicity with very limited control signal overhead.
A resource-shift within the context of the present disclosure is hence a transferring of an allocation from one radio resource unit to another, typically but not necessarily time-adjacent, radio resource unit without changing of the time-reference of the frame structure in which the radio resource units are transmitted. This in contrast to merely shifting the time-reference of a transmitting signal, such as for example wellknown from source clock drift adjustments or adjustment of a timing advance to accommodate propagation delay.
The radio resource time unit may be one of a symbol, mini-slot, slot, subframe, frame, superframe or any other unit used by the air interface. It may be understood that the radio resource time unit is not necessarily the smallest granularity resource within the air interface, but can for example also be a resource unit in which the persistent scheduling is provided. For example, the persistent scheduling may be provided in units of subframes, wherein a subframe is further divisible in slots.
One skilled in the art will appreciate that the resource-shifts may be applied periodically. For examine, in the example depicted in
In one embodiment, a resource-shift may be provided for a persistent allocation in accordance with an equation:
wherein Pfractional denotes the desired fractional periodicity and Pconfigured denotes the configured periodicity, where n∈+ denotes the nth resource after the first resource configured by the persistent allocation.
In another embodiment, one or more delays may be provided for the resources immediately following the first resource. For example, in relation to
In yet another embodiment, it may be desired to provide non-persistent advances or delays to the configured persistent allocation. That is, unlike in the case of persistent advances or delays, only the resource indicated to be resource-shifted is resource-shifted without impact on any subsequent resource of the persistent allocation. Naturally it is also possible to provide persistent and non-persistent resource-shifts in combination.
In a further embodiment, it may be desirable to provide persistent resource advance or resource delay in accordance with a drifted packet arrival time. While a persistent allocation may have been configured in accordance with configured periodicity that matches a periodic packet arrival time of a service at the transmitter or may be configured with a configured periodicity that is matched to a desired fractional periodicity through resource advances and/or delays, a drift may occur between the matched periodicity and the periodic packet arrival time at the transmitter. This may for example occur if the clock running the service generating the packets to be transmitted is not matched to the clock of the radio interface, which in essence causes the packets to arrive at the radio transmitter with a fractional persistency. For a persistent uplink allocation, a user equipment may inform a base station of a need to insert a resource advance or resource delay for this purpose. This may be triggered at the UE by a determination that the time interval between the packet arrival time at the UE's radio interface and the corresponding persistent resource becomes too large (meriting a resource advance) and/or too small (meriting a resource delay). A similar trigger based determination may be made by a base station for a downlink persistent allocation.
To facilitate signaling of a persistent allocation, signaling may be performed in accordance with known art. For example, a persistent allocation may be configured and activated in accordance with the 3GPP LTE standard. In accordance with embodiments of the invention as depicted in
In accordance with other embodiments of the inventions, a resource-shift may be indicated with a one bit indication, where one value of the bit indicates no resource-shift is to be performed and the other value indicates as depicted at 320 that an advance is to be performed, whereas, as depicted at 330, the other value indicates that a delay is to be performed. Whether to associate the other value with advance or delay may for example be signaled with the configuration of the persistent allocation. Signaling in accordance with embodiments 310, 320 and 330 may for example be performed in a medium access control information element (MAC IE) or by a physical layer signaling or in radio resource control (RRC) signaling.
In an alternative embodiment, the resources to periodically delay or advance may be indicated with the configuration of the persistent allocation, such that no individual signaling per persistent resource is required. For example, in accordance with the example as depicted in
In yet another alternative embodiment, the desired fractional periodicity may be signaled with the configuration of the persistent allocation. A user equipment may then derive the occurrences of resource-shifts from the configured periodicity and the desired fractional periodicity from a rule mutually understood by a network node providing the persistent allocation and a user equipment receiving the persistent allocation. Such a rule may for example be the equation provided supra. In such cases, the network node may not explicitly signal the configured periodicity, but signal the configured periodicity implicitly through the desired fractional periodicity, wherein a user equipment may derive the configured periodicity from the signaled desired fractional periodicity, for example by one of a rounding, ceiling or floor function.
In certain embodiments, a user equipment might request a base station to provision a persistent allocation to the user equipment in accordance with a desired fractional periodicity. In such a case, it is for example possible that the base station and user equipment are configured to commonly interpret an allocation of a persistent allocation with a configured periodicity to implicitly signal that the desired fractional periodicity is provided, for example when the configured periodicity corresponds to the requested desired fractional periodicity according to a rule such, where a rule may be provided by one of a rounding, ceiling or floor function. In such an embodiment, the indication of the resource shift may thus signaled through the configured periodicity.
At 550, a persistent resource allocation is received, generally comprising an indication of a configured periodicity of allocated resources. The indication may contain the configured periodicity of allocated resources or a desired fractional periodicity from the configured periodicity may be derived. At 560, a resource shift indication is received. The resource shift for example be contained in a RRC or MAC IE or physical layer signaling and may be formatted as depicted in
The at least one memory (610) may store computer programs, which may, when executed by the at least one processor (620), for example in combination with any of the at least one transceiver (630), at least one amplifier (640) and at least one antenna unit (650), perform embodiments of the invention. For example an infrastructure node or user equipment may be embodied in apparatus 600.
Embodiments of the invention may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit or field programmable gate array), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional non-transitory computer-readable media.
Although various aspects are set out above, other aspects comprise other combinations of features from the described embodiments, and not solely the combinations described above.
This application claims priority from U.S. Provisional Application No. 62/5209,97, filed on Jun. 16, 2017.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2018/054389 | 6/14/2018 | WO | 00 |
Number | Date | Country | |
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62520997 | Jun 2017 | US |