CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International patent application PCT/CN2018/094875, filed on Jul. 6, 2018, which claims priority to foreign Great Britain patent application No. GB 1712909.9, filed on Aug. 11, 2017, the disclosures of which are incorporated by reference in their entirety.

TECHNICAL FIELD

The current disclosure relates to bundling of slots in a wireless communication system, and in particular to bundling mini-slots in a cellular communication system.

BACKGROUND

Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP). The 3rdgeneration of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards a broadband and mobile system.

The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN), for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB). More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB.

NR proposes an OFDM transmission format for the wireless link of the system. OFDM systems utilise a number of sub-carriers spaced in frequency, each of which is modulated independently. Demodulation of the set of the sub-carriers allows recovery of the signals. Time slots are defined for the scheduling of transmissions, which each slot comprising a number of OFDM symbols. NR has proposed 7 or 14 OFDM symbols per slot. The sub-carriers, or frequency resources, within each slot may be utilised to carry one or more channel over the link. Also, each slot may contain all uplink, all downlink, or a mixture of directions.

NR also proposes mini-slots (TR 38.912) which may comprise from 1 to (slot-length-1) OFDM symbols to improve scheduling flexibility. Each mini-slot may start at any OFDM symbol within a slot (provided the resources are not pre-allocated to channels, for example PDCCH). Some configurations may be limited to systems over 6 GHz, or to a minimum mini-slot length of 2 OFDM symbols.

5G proposes a range of services to be provided, including Enhanced Mobile Broadband (eMBB) for high data rate transmission, Ultra-Reliable Low Latency Communication (URLLC) for devices requiring low latency and high link reliability, and Massive Machine-Type Communication (mMTC) to support a large number of low-power devices for a long life-time requiring highly energy efficient communication.

TR 38.913 defines latency as “The time it takes to successfully deliver an application layer packet/message from the radio protocol layer 2/3 SDU ingress point to the radio protocol layer 2/3 SDU egress point via the radio interface in both uplink and downlink.” For URLLC, the target for user plane latency is 0.5 ms for uplink (UL), and 0.5 ms for downlink (DL).

TR 38.913 defines Reliability as “Reliability can be evaluated by the success probability of transmitting X bytes within a certain delay, which is the time it takes to deliver a small data packet from the radio protocol layer 2/3 SDU ingress point to the radio protocol layer 2/3 SDU egress point of the radio interface, at a certain channel quality (e.g., coverage-edge).” For URLLC, a reliability requirement for one transmission of a packet is defined as 1×10−5for 32 bytes with a user plane latency of 1 ms.

The following disclosure particularly addresses the provision of low latency and high reliability services (URLLC type).

The present invention is seeking to solve at least some of the outstanding problems in this domain.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

There is provided a method of downlink data transmission from a base station to a UE in a cellular communication system utilising an OFDM modulation format, the method comprising the steps of scheduling transmission of a Transport Block of data in a first mini-slot comprising at least one OFDM symbol defined within a slot of the transmission format; scheduling a repeated transmission of the Transport Block of data in at least one subsequent mini-slot comprising at least one OFDM symbol; transmitting an indication of the scheduling from the base station to the UE; and transmitting the Transport Block as defined by the scheduling from the base station to the UE.

The first and at least one subsequent mini-slots may start at the same time, but utilise different frequency resources.

The first and at least one subsequent mini-slots may start at different times.

The first and at least one subsequent mini-slots may use the same frequency resources, or may use different frequency resources.

The first and at least one subsequent mini-slots may be located in the same slot, or in different slots.

The indication of scheduling may be transmitted in a DCI message on the PDCCH of a slot.

The indication of scheduling may be transmitted in the first mini-slot.

The indication of scheduling may be transmitted in a DCI message on the PDCCH transmitted in the first mini-slot.

The UE may be configured to transmit an ACK signal if a mini-slot is successfully decoded, and wherein the base station does not transmit further scheduled repetitions of that mini-slot after receipt of the ACK.

The UE may be configured to only transmit a NAK signal if a mini-slot has not been successfully decoded after all repetitions of that mini-slot have been received.

There is also provided a method of uplink data transmission from a UE to a base station in a cellular communication system utilising an OFDM based modulation format (either Cyclic-prefix OFDM or Discrete Fourier Transform Spread OFDM), the method comprising the steps of scheduling transmission in accordance with available resources of a Transport Block of data in a first mini-slot comprising at least one OFDM symbol defined within a slot of the transmission format; scheduling a repeated transmission in accordance with available resources of the Transport Block of data in at least one subsequent mini-slot comprising at least one OFDM symbol; and transmitting the Transport Block as defined by the scheduling from the UE to the base station.

The first and at least one subsequent mini-slots may start at the same time, but utilise different frequency resources.

The first and at least one subsequent mini-slots may start at different times.

The first and at least one subsequent mini-slots may use the same frequency resources, or different frequency resources.

The first and at least one subsequent mini-slots may be located in the same slot, or may be located in different slots.

The indication of scheduling is transmitted in a DCI message on the PDCCH of the slot in which at least the first mini-slot is located.

The base station may be configured to transmit an ACK signal if a mini-slot is successfully decoded, and wherein the UE does not transmit further scheduled repetitions of that mini-slot after receipt of the ACK.

The base station may be configured to only transmit a NAK signal if a mini-slot has not been successfully decoded after all repetitions of that mini-slot have been received.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

