EP3571882A1

EP3571882A1 - Resource allocations

Info

Publication number: EP3571882A1
Application number: EP17893349.5A
Authority: EP
Inventors: Karol Schober; Klaus Hugl; Timo Lunttila
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2017-01-18
Filing date: 2017-01-18
Publication date: 2019-11-27
Also published as: WO2018134468A1; EP3571882A4

Abstract

There is provided a method, comprising: receiving, by a receiving device from a transmitting device, a resource allocation for short transmission time interval, sTTI, data, wherein the sTTI data is scheduled according to short transmission time intervals to the receiving device; extracting from the resource allocation an indication on whether or not a resource reservation for regular transmission time intervals needs to be taken into account or not; and decoding the sTTI data at least partly based on the indication.

Description

RESOURCE ALLOCATIONS

FIELD OF THE INVENTION

The invention relates generally to radio resource allocations.

BACKGROUND

It is desirable to make radio communication more efficient. One option to do so is reducing latency by applying short transmission time intervals (sTTIs) as well as shortened transmission durations. However, a problem may exists on how to act when radio allocations according to sTTIs and other radio allocations collide.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of the invention, there is provided a method as specified in claims 1 and 12.

According to an aspect of the invention, there are provided apparat-uses as specified in claims 17, 29 and 37.

According to an aspect of the invention, there is provided a computer pro- gram products as specified in claims 36 and 37.

According to an aspect of the invention, there is provided an apparatus comprising processing means configured to cause the apparatus to perform any of the embodiments as described in the appended claims.

Some embodiments of the invention are defined in the dependent claims. LIST OF THE DRAWINGS

In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which

Figure 1 presents an example communication scenario to which embodiments are applicable to;

Figures 2, 6, and 8 illustrate scheduling of data within one subframe and different options for handling any overlapping parts, according to some embodiments;

Figures 3, 4, 9 and 11 show methods, according to some embodiments;

Figures 5 and 7 illustrate flow diagrams, according to some embodiments;

Figure 10 shows different options for handling the part of overlap, accord- ing to some embodiments; and

Figures 12 and 13 show apparatuses, according to some embodiments.

DESCRIPTION OF EMBODIMENTS

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

Embodiments described may be implemented in a radio system, such as in at least one of the following: Worldwide Interoperability for Micro-wave Access (Wi- MAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Ad- vanced, LTE-Advanced Pro and/or 5G system. The LTE-Advanced Pro system, may be- come part of 3GPP LTE Rel-14/15.

The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties. One example of a suitable communications system is the 5G system, as listed above. The 3GPP solution to 5G is referred to as New Radio (NR). 5G has been envisaged to use multiple-input-multiple-output (MIMO) multi-antenna transmission techniques, more base stations or nodes than the current network deployments of LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller local area access nodes and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates. 5G will likely be comprised of more than one radio access technology (RAT), each optimized for certain use cases and/or spectrum. 5G mobile communications will have a wider range of use cases and related applications including video streaming, aug- mented reality, different ways of data sharing and various forms of machine type applications, including vehicular safety, different sensors and real-time control. 5G is expected to have multiple radio interfaces, namely below 6GHz, cm Wave and mmWave, and also being integradable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter- radio interface operability).

It should be appreciated that future networks will most probably utilize network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or cloud data storage may also be utilized. In radio communications this may mean node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be nonexistent. Some other technology advancements probably to be used are Software-De- fined Networking (SDN), Big Data, and all-IP, which may change the way networks are being constructed and managed.

Figure 1 illustrates an example of a communication system to which embodiments of the invention may be applied. The system may comprise an access node 110 providing a cell 100. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. In another point of view, the cell may define a coverage area or a service area of the access node 110. The network node 110 may be an evolved Node B (eNB) as in the LTE and LTE-A, an access point of an IEEE 802.11-based network (Wi-Fi or wireless local area network, WLAN), or any other apparatus capable of controlling radio communication and managing radio resources within a cell. For 5G so- lutions, the implementation may be similar to LTE-A, as described above. The access node 110 may be called a base station or a network node. The system may be a cellular communication system composed of a radio access network of access nodes, each controlling a respective cell or cells. The access node 110 may provide user equipment (UE) 120, 122 (one or more UEs) with wireless access to other networks such as the Internet. The wireless access may comprise downlink (DL) communication from the eNB 110 to the UE 120, 122 and uplink (UL) communication from the UE 120, 122 to the eNB 110. Additionally, one or more local area access nodes may be arranged within a control area of a macro cell access node. The local area access node may provide wireless access within a sub-cell that may be comprised within a macro cell. Examples of the sub-cell may include a micro, pico and/or femto cell. Typically, the sub-cell provides a hot spot within a macro cell. The operation of the local area access node may be controlled by an access node under whose control area the sub-cell is provided.

In the case of multiple access nodes in the communication network, the access nodes may be connected to each other with an interface. LTE specifications call such an interface as X2 interface. In IEEE 802.11 networks, a similar interface is provided between access points. Other communication methods between the access nodes may also be possible. The access node may be further connected via another interface to a core network 130 of the cellular communication system. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise a mobility management entity (MME) 132 and a gateway node 134. The MME may handle mobility of terminal devices in a tracking area encompass- ing a plurality of cells and also handle signalling connections between the terminal devices and the core network 130. The gateway node 134 may handle data routing in the core network 130 and to/from the terminal devices.

As said in the background part, there may be need to reduce latency in future communication systems. One way to reach this may be to use short/shortened transmission time intervals (sTTI) and correspondingly shortened transmission durations, as well as reduced processing times. The TTI is a parameter related to encapsulation of data from higher layers into frames for transmission on the radio link layer. TTI refers to the interval between transmissions on the radio link. The TTI is usually the same as the minimum duration of a transmission on a radio link. The TTI is related to the size of the data blocks passed from the higher network layers to the radio link layer. In the terminology of this application, a sTTI may be short (or at least shorter) compared to previous Release's TTI (i.e. legacy TTI), which may correspond to e.g. 1 millisecond (ms), i.e. one subframe equal to 14 OFDM symbols with normal cyclic prefix (CP) in LTE. The sTTI for LTE may be e.g. 2, 3, and 7 symbols, when a normal cyclic prefix (CP) is applied. Also sTTIs of a different length are possible, although currently not pursued in 3GPP. Consequently, it is important to assess specification impact and performance of TTI lengths between a slot length (6/7 symbols = 0.5ms) and one modulation symbol (in LTE downlink these may be called orthogonal frequency division multiplexing (OFDM) symbols, in LTE uplink these may be called single carrier fre- quency division multiplexing (SC-FDM) symbols), taking into account impact on reference signals and physical layer signalling. In the NR context, a shorter transmission time interval is often referred to as mini-slot.

It is expected that the UE 120 is able to receive a (legacy) physical downlink shared channel (PDSCH) applying the legacy (e.g. 1 ms) TTI length as well as shortened PDSCH (sPDSCH) applying the sTTI length, meaning that switching between or even simultaneous reception of a sTTI and legacy TTI length needs to be supported. Consequently, the UE 120 may support a shortened physical downlink control channel (sPDCCH), i.e. a PDCCH for a short TTI. Let us assume in the following that the UE 122 is only capable to operate with legacy PDSCH and legacy /regular TTI. One aspect of sTTI control operation is scheduling mechanism. Two scheduling schemes for sTTI are proposed. In first one, a single-step downlink control information (DCI) with radio resource control (RRC) configured search space is proposed. However this may lead into suboptimal multiplexing performance of legacy 14 OFDM symbols (OS) long TTI and sTTI.

In a second one, a two-step DCI / scheduling mechanism is proposed. This two-step DCI from the eNB to the UE(s) may comprise e.g. 1) a fast short/shortened DCI (let us call this sDCIl) dynamically scheduling the sPDSCH (on sTTI basis) and 2) a slow short/shortened DCI (let us call this sDCI2). In an embodiment, these sDCIl and sDCI2 are different control messages. The sDCI2 is proposed to be transmitted less often than the sDCIl and to contain additional information for the sTTI operation. For example, the sDCI2 may contain information that enables more efficient multiplexing of sTTI with legacy TTI for transmission control protocol (TCP) slow-start traffic and or adjustment of control resources for the transmission of sDCIl, to mention only a few possible additional information contents.

In other words, in one embodiment of this latter proposal a sPDSCH/sPUSCH (a short/shortened physical uplink shared channel) is scheduled by a UE-specific first sDCI (i.e. sDCI 1), and the second sDCI transmitted in PDCCH region (i.e. sDCI 2) or e.g. via higher layer signalling such as radio resource control (RRC) or medium access control (MAC) signaling indicates additional information that is use- ful/beneficial for sTTI. This information may be e.g.

• adjustment of sPDCCH search space and/or frequency resource for the following sTTI (s), compared to an RRC configured sPDCCH search space and/or frequency resource set. E.g. adjustment of downlink control resources (of sPDCCH in sTTIs, used to schedule sDCIl)

• legacy LTE-UEs (e.g. the UE 122) resource allocation information (i.e. PDSCH-resource allocation-information), or more generically, resources that should be excluded from sTTI use.

• sTTI operation activation and deactivation.

In case the UE 120 does not detect the sDCI2, the UE 120 may monitor the RRC configured sPDCCH search space and/or frequency resource set. It is to be noted that other information in sDCI2 is not precluded. The sDCI2 can be user-specific, user group-specific or common to all UEs in an sTTI in a cell. An advantage of a common sDCI2 is that it introduces small additional overhead because at most one sDCI2 is transmitted in a subframe. Due to the TTI shortening, to keep the total size of a radio resource allocation in terms of resource elements similar as with 1-ms legacy TTI, the frequency allocations for sPDSCH/sPUSCH with sTTIs may be wider. Consequently, the scheduling overhead of fast sDCIl can be reduced assuming a larger resource allocation granular- ity in frequency domain. Note that a reduction of the downlink (DL) control overhead on sPDCCH may be considered an important part of the short TTI design. Therefore, it is common understanding that for sTTI the size of a scheduling unit called a RBG (resource block group) is increased and most likely will be an integer multiple (2, 3, 4 x) of the legacy RBG size. When the size of a sTTI RBG is larger than that of legacy RBG, delivery of the PDSCH-resource allocation-information of the legacy 1ms TTI PDSCH allocation having the finer, legacy resource allocation granularity to the sTTI UE 120 becomes beneficial and increases the scheduling efficiency or eases the scheduling at the eNB 110 as such. If an sTTI UE 120 has knowledge of the 1ms TTI PDSCH resource allocation (e.g. of the UE 122) within the subframe, it can be scheduled around (rate- matched around) this resource in frequency (i.e. the data intended for the sTTI UE 120 can be mapped onto resources other than those used by the 1ms TTI PDSCH resource allocation), which eases the coexistence of legacy TTI and sTTI within one subframe. It may not be practical to reserve fully orthogonal resources for TTI (e.g. UE 122) and sTTI (e.g. UE 120) users. E.g. if the RBG size for sTTI is large, e.g. 20 PRBS, and legacy UEs 122 allocation is just a few (e.g. 4) PRBs, there would be 16 unused PRBs around the legacy TTI PDSCH. However, if overlap with scheduling is allowed, those resources can be given for the sTTI UE 120.

This is illustrated in Figure 2. The Figure depicts on horizontal axis a time duration of 1 subframe (i.e. 1ms). The DL subframe is divided into six sTTI parts, each having 2 or 3 OFDM symbols (OS). The reason for varying number of symbols is that the 2 -OS sTTI structure preserves the slot-boundary structure within the subframe, as 2+2+3=70S corresponds to the slot duration. The sTTI allocations may comprise in time domain one sTTI-x, for example, while the legacy PDSCH allocation may be one subframe long (excluding the control part of the subframe occupied by PDCCH (here corresponding to sTTI-0)).

In frequency domain (vertical axis), the figure depicts 10 MHz bandwidth (BW) comprising 50 resource blocks (RBs), referred in a figure as PRBs. It should be noted here that RB term is used in the application to represent the frequency (vertical axis) division. One RB in frequency may comprise certain number of subcarriers, such as 12 subcarriers as in LTE-A. In horizontal (time) domain, one PRB/RB may comprise e.g. 2 OFDM symbols for the sTTI UEs and 7 symbols for the legacy UEs (including the control part of 2 OFDM symbols). As such, there may be so called legacy PRBs for legacy UEs comprising e.g. 7 symbols (in case of normal prefix) and so called short PRBs (sPRBs) for sTTI UEs comprising e.g. 2 symbols (depending on the time domain granularity of sTTI allocations). In the following, terms RB or PRB in connection of sTTI data denote the sPRBs. In other words, the term 'PRB' or 'RB' corresponds to the scheduling unit in frequency domain, and the length of a 'PRB' or 'RB' (in time domain) may vary in different embodiments depending e.g. on TTI length and to whom and for what purpose the resources in the RB are allocated/reserved. Also the Figures are useful in illustrating what the size (in frequency and in time domain) of a given RB is in any of the presented non-limiting example embodiments.

Further, the BW is, for illustration purposes, divided into 4 subbands (SB), out of which SB#4 comprises 14 PRBs, while other SBs comprise 12 PRBs. As such, the dashed horizontal lines express 3 PRB changes, which may be equal to legacy RBG size. In the Figure 2 a resource allocation granularity/subband size for the sTTI is assumed to be 12 or 14 PRBs. However, it needs to be noted that this Figure (and any corresponding figure in the application) depicts one non-limiting example embodiment, and other arrangements to divide the subframe and bandwidth are possible. For example, if the sTTI length was one symbol, then the subframe would be divided in time domain into 14 sTTIs, instead of six. As another example, similar concept could be provided for different bandwidths, possibly with different number of subbands and subband sizes/resource allocation granularities. As further example, assuming extended CP, the number of OFDM symbols in the subframe may be 12 instead of 14 for LTE-A.

Let us assume that a sTTI UE receives an allocation for subbands SB#1 and SB#2 in sTTI-2. This means in this example figure an allocation of 24 PRBs correspond- ing to vertically dashed block labelled as "sPDSCH" in the Figure which runs all the way through the SB #1 and SB#2. This allocation may have been received in one of the sPDCCHs carrying sDCll in sTTI-2, e.g. the one that is present in the intersection of sTTI-2 and SB#2. Each sTTI duration may have one or more sPDCCH (including sDCI 1) in order to allow dynamic sPDSCH scheduling, i.e. in this example scheduling is possi- ble every 2 or 3 symbols. sTTI-1 and sTTI-5 have a sTTI length of 3 OFDM symbols while the corresponding sPDCCHs may not need to occupy all 3 OFDM symbols of the respective sTTIs as shown in Figure 2.

The Figure also shows that one or more legacy UEs have also been scheduled in the subframe. These are presented with the dotted blocks labelled "legacy PDSCH". These DL resource allocations may have been received in the "legacy DCI" labelled control signalling on the legacy PDCCH, for example, or in a plural of such control signalling, depending on which one or more UEs are allocated with these legacy PDSCHs.

It needs to be noted that the resource allocations for both sPDSCH and legacy PDSCH are non-limiting examples and may vary from what is shown. E.g. the legacy PDSCH resource allocation on SB#3 could similarly be on SB#4, and then the labels "dep on sDCI2" and "indep. on sDCI2" would be vice versed. Also the RBG/PRB sizes may vary from what is shown in the Figures.

The figure thus illustrates an example of sPDSCH scheduling, where the sPDSCH is allocated with 12-PRB (or 14PRB, see SB#4) granularity, and the legacy PDSCH with 3-PRB granularity in 10MHz BW (50 PRBs total). The sDCI2 is transmitted in the legacy PDCCH (or is signalled by higher layers) and contains information about resources reserved or dynamically used for non-sTTI use, such as resource allocation of legacy PDSCH.

It may occur that one of the legacy PDSCH allocations overlaps (collides) at least partially the same resources as the sTTI allocation. In the Figure 2 this happens in SB#1 of sTTI-2, see the 3-PRB block with left leaning diagonal dashes and marked as "coll." in the SB#1 area. In other words, the eNB decides to allocate sPDSCH on top of earlier scheduled legacy PDSCH, such that the sPDSCH collides with the legacy PDSCH in 3 PRBs out of a total of 24 PRBs scheduled/allocated for sPDSCH.

Now the sTTI UE 120, which successfully receives and decodes the sDCI2 possibly present in the legacy PDCCH region containing the information PDSCH-re- source allocation-information may obtain knowledge of this legacy allocation and thus exclude the resources allocated for the legacy UE 122 from its own sPDSCH resource allocation. As a result, the sTTI UE 120 is in practice served with 21 PRBs in sTTI-2, instead of 24 PRBs. The problem may be that in this case the reception of the sPDSCH for this sTTI UE 120 is dependent on the successful reception of sDCI2. If sDCI2 is missed by the sTTI UE 120, it will think it is scheduled with 24 PRBs instead of 21 PRBs and assume sPDSCH data to also be available in the overlap of PDSCH and sPDSCH. This occasion may results in erroneous reception of sPDSCH data, leading to a negative acknowledgment, NACK, feedback with 100% probability because (a) the UE 120 will have a different transport block size (TBS) assumption given the different assumed resource allocation (in number of PRBs defining the TBS) and (b) will not assume rate- matching around the PDSCH resource allocation destroying the bit ordering of sPDSCH. However, the sTTI UE 120 scheduled with sPDSCH only in the subband SB#2 is fully independent of the sDCI2 (reception) as no legacy PDSCH allocation is present.

Therefore, it may be desirable to make the faster (more frequently transmitted) sDCIl independent of the slower (less frequently transmitted) sDCI2, which means that any UE should be able to decode the sDCIl (and the sPDSCH scheduled by sDCIl) even without sDCI2 being present/transmitted or successfully decoded. This addresses the reliability issue introduced by the two-step DCI approach. Therefore, at least an UE with a low latency traffic should be able to operate based on the single- step DCI, only listening to sDCIl. At the same time, one challenge is how to make the information in the sDCIl and the sDCIl itself independent from sDCI2, without jeopardizing the benefits of the additional information contained in the sDCI2.

At least partially to tackle this problem and to propose sophisticated means to schedule short TTI data smartly on top of long TTI data, there is proposed, as illustrated in Figure 3, a method performed by a receiving device. Let us in the following consider that the receiving device is an UE (e.g. the UE 120) and the transmitting device is an access node (e.g. the eNB 110). Thus, downlink transmission is assumed. It needs to be noted that in some embodiments the transmitting device may be a UE and the receiving device may be an eNB (uplink), or both the transmitting device and receiving devices are UEs (device-to-device communication). Although the scenario is herein depicted in cellular scenario, the method may be applied in e.g. WLAN (IEEE 802.11) environment.

In step 300, the UE receives from the eNB, a resource allocation for data that is to be transmitted according to sTTIs to the UE (let us call this data as sTTI data). The resource allocation may be received as a dedicated signaling to the UE, e.g. in the sDCIl. The resource allocation message may indicate resources on which the eNB is planning to send data to the UE. The frequency resources of the sTTI to be used for the data communication may be decodable from the resource allocation, which indicates which resources (e.g. resource elements or resource blocks) are allocated to the UE for carrying the data according to the sTTIs. It may be noted that one RB may also carry other signals, e.g. reference signals, to the UE, not only user data.

In some embodiments, the resource allocation is comprised in a first DCI on a sPDCCH. For example, the resource allocation may be comprised in the sDCIl and may be transmitted over control signaling on e.g. legacy PDCCH or short PDCCH. The DCI as such may comprise also other information than the radio resource alloca- tion/reservation. In some embodiments, DCI (also sDCIl) may comprise information regarding at least one of the following: applicable modulation and coding scheme (MCS), demodulation requirements, precoding, power control, channel state information (CSI) report request, and hybrid automatic repeat request (HARQ) related information.

In step 302, after receiving the resource allocation (also called the sDCIl) in the following, the UE extracts from that an indication on whether or not a resource reservation for regular TTIs/PDSCH needs to be taken into account or not. In an embodiment, the resource allocation is transmitted more frequently than the resource reservation.

In some embodiment the regular TTI may be called a normal or a long TTI. In some embodiments, the transmission time interval of each regular TTI corresponds to a predetermined length, whereas the transmission time interval of each sTTI is shorter than a predetermined length. In some embodiments, the predetermined length of the TTI corresponds to one sub-frame (e.g. 1 ms as in LTE-A). In some embodiments, the regular TTI is a legacy TTI.

In some embodiments, the indication may a one bit indication ('1' meaning the resource reservation needs to be taken into account and '0' meaning that the resource reservation need not be taken into account, or vice versa). Other kinds of indications (e.g. multiple bits) are possible as well.

The resource reservation may be comprised in a second DCI on a PDCCH, as shown in Figure 2. For example, the resource reservation may be part of the sDCI2 of Figure 2. As an alternative option, as indicated above, the resource reservation may be comprised in RRC or MAC signaling.

In some embodiments, the resource reservation does not allocate resources for other data, but may indicate those normal/regular/long TTI resources or resource blocks which should be excluded from the sTTI use for any purpose, and are to be deducted from the sTTI resource allocations. However, in some embodiments, the resource reservation informs the receiver of a second resource allocation for data. That is, the resource reservation may indicate allocated data that is to be transmitted according to the regular TTIs to some other one or more UEs (e.g. the UE 122). The resource reservation may thus be in some embodiments interpreted as an indication of an aggregated resource allocation of all or subset of the legacy UEs that are scheduled in the given (legacy) TTI (such as in a given subframe). In some embodiments, the second resource allocation may be the information element called PDSCH-resource allocation-information described above. The resource reservation may be either sent by the eNB to a specific UE, e.g. the UE 120, as a dedicated signaling or it may be broadcasted /multicasted.

In some embodiments the resource reservation reserves RBs for the same subframe as the resource allocation message. E.g. it may allocate radio resources for data that is to be transmitted in the same subframe as the data allocated in the (first) resource allocation message for sTTI data. In some embodiments, the resource reservation message is conveyed in the same subframe as the resource allocation.

Let us in the following, for simplicity of description, consider that both the resource allocation and the resource reservation are radio resource allocations comprised in the sDCIl and in the sDCI2, respectively. Therefore, in the following functions/aspects related to the sDCIl may be considered to apply to the resource allocation (e.g. resource allocation) and the functions/aspects related to the sDCI2 may be considered to apply to the resource reservation.

As said, in step 302, the UE checks/extracts the indication from the sDCIl whether the sDCI2 needs to be taken into account or not. Then in step 304, the UE decodes the data transmitted according to the sTTIs (a.k.a. sTTI data) at least partly based on the indication. This may mean that the manner of decoding and which RBs to use for the decoding may differ depending on the indication received in the sDCIl. Let us take a look at this more closely later.

Looking from a point of view of the transmitting device (e.g. eNB 110) in Figure 4, the method comprises in step 400, the eNB determining the indication of whether or not the resource reservation needs to be taken into account, and then in step 402 the eNB including in the resource allocation the indication. In step 404 the method comprises the eNB transmitting to the UE the resource allocation comprising the indication. Consequently, the eNB may then in step 406 transmit the sTTI data at least partly based on the indication. This will also be looked more closely later.

As described, one aspect of the proposal is to add e.g. a 1 bit indication (called sDCI2-ignore-bit) to the sDCIl which changes the behaviour of the UE and/or the eNB. E.g. if the bit is OFF, then the UE shall take the PDSCH-resources-allocation- information in the sDCI2 into account. On the other hand, if this bit is ON, then the UE may ignore PDSCH-resources-allocation-information in the sDCI2 (or received through the higher layer configuration). Such indication may be beneficial to improve the efficiency of the communication of the network, and especially of the sTTI UE 120. When e.g. ultra-reliability low latency communication (URLLC) traffic is transmitted to that particular sTTI UE 120 instead of low-reliable+low-latency traffic (such as transmission control protocol (TCP) slow start traffic), it may be beneficial for the UE to know does it need to take the information of sDCI2 (or the corresponding higher layer configuration/signaling) into account or not.

Let us first look as the scenario where the sDCI2 need not be taken into account. This is shown in Figures 5 and 6. Figure 6 is similar as Figure 2 but the colliding part is handled efficiently. Some assumption not shown in Figure 5 include that the eNB configures the sTTI mode to the UE and at the same time configures the UE to follow/monitor common-slow DCI (i.e. sDCI2). The configuring may happen via higher layer signaling, and/or via broadcast/multicast. As said, an alternative manner for configuring the UE to follow sDCI2 is to convey information corresponding to the sDCI2 with higher layer signaling (MAC or RRC, for example). However, in this example, it is assumed that the eNB transmits the sDCI2 with PDSCH-resource-allocation- information in the legacy PDCCH, as shown in Figures 2, 6 and 8.

Figure 5 shows that the eNB sets the indication in step 500. In some em- bodiments, the eNB may set the indication at least partly based on whether or not the resource reservation indicates RBs that are at least partially overlapping with the RBs indicated in the resource allocation. If the RBs are non-overlapping, then the UE may ignore the sDCI2. On other hand, if the RBs are overlapping, the UE may need to pay attention to the sDCI2, in order to improve the probabilities of successful decoding of the sTTI data. In some embodiments, even if the RBs are overlapping, the eNB may set the indication so that the UE may ignore the sDCI2. This may depend e.g. on priority of the data allocated in the sDCI l. In other words, setting the indication may further be based on the priority of the data allocated in the sDCIl. In some embodiments, the setting may be based on relative priorities of the legacy PDSCH data allocation indi- cated in the sDCI2 compared to the data allocated in the sDCIl. These are only some possible non-limiting criteria for the setting, and others may be included alternatively or in addition to these.

In this example it is considered that the indication is to ignore the sDCI2. This may be due to non-overlapping RBs. On the other hand, as is the case in this ex- ample of Figure 6, there may be overlapping resources (3 PRBs out of a total of 24 PRBs scheduled), but the indication may still be set to ignore sDCI2, as explained above. In such case the sTTI data may be punctured into the legacy PDSCH and the UE may fully operate without sDCI2 knowledge. In this case the legacy PDSCH may suffer but the sPDSCH may benefit. The eNB thus includes the indication to the sDCIl carry- ing a DL assignment/allocation for a sPDSCH, and sends the sDCIl with the indication (set to ignore sDCI2) to the UE in steps 402 and 404 (same as in Figure 4). In step 302 in Figure 5 the UE extracts the indication from the received sDCIl.

As the eNB knows that the UE most likely, based on the indication, ignores (or does not even decode) the sDCI2, the eNB in step 502 determines that each RB indicated in the sDCIl is to be used in carrying sTTI data to the UE, and then in step 506 transmits the sTTI data to the UE on the indicated RBs over the sPDSCH. That is, all the sPDSCH RBs mapped according to sDCIl are used and the eNB transmits sPDSCH sTTI data also on the colliding 3PRBs, as shown in Figure 6.

The UE in step 504, based on the received indication, determines that each RB indicated in the sDCIl carries sTTI data to the UE. Consequently, the UE may in step 508 decode the sTTI data (i.e. data transmitted according to the short transmission time intervals) by assuming that each of the RBs nominally scheduled in the sDCIl to carry sTTI data to the UE are available for sTTI transmission. For the decoding, the UE may determine transmission block size (TBS) as well as the sPDSCH resource mapping based on the resource allocation received sDCIl. This is a basic assumption for the UE after receiving the sDCIl. After getting the ignore-indication that the UE need not care about sDCI2, the basic assumption is confirmed (i.e. the eNB also acts accordingly). This proposal makes the communication efficiency better (e.g. faster) and saves decoding/processing resources from the UE 120, because it does not need to use time/resources for sDCI2 which the UE otherwise (without the indication) would decode.

In some embodiments, the UE may then refraining from decoding the sDCI2. This is because the sDCIl indicates that sDCI2 can be ignored, the UE may intentionally omit decoding efforts of sDCI2. However, although the indication may indicate that sDCI2 may be ignored, the UE may still receive and decode the sDCI2. This may be beneficial as in some cases the UE may receive the sDCI2 before the indication in sDCIl. In such circumstances, the UE may not wait until it receives the sDCIl with IGNORE-indication to start reading the sDCI2, and the UE may decode sDCI2 as soon as it receives sDCI2 (before sDCIl), which may be beneficial for latency purposes. Then the indication of "can be ignored" may indicate to the UE that the decoded information of sDCI2 need not be considered when receiving sTTI data. As such, in some embodi- ments the UE shall not take the information into account. This may still reduce the processing time of sTTI data.

Let us then look at the case where the indication is set so that the UE needs to pay attention to the sDCI2 with respect to Figures 7 to 9. This may be due to the eNB receiving some normal TTI resources for other use, i.e. excluding some resources from the sTTI use. This may also be due to eNB's decision to prioritize legacy PDSCH data on overlapping resource allocations for sPDSCH and legacy PDSCH. For example, the eNB may have an overlapping PDSCH within the sPDSCH allocation. The eNB may puncture the overlapping PDSCH from the sPDSCH allocation, as shown in Figure 8 and inform the UE 120 by using the legacy PDSCH-resource-allocation-information in sDCI2 and the indication to 'Do not ignore' in sDCIl. The UE 120 can then use this information to aid the receiver operation by special handling of the resource elements belonging to the legacy PDSCH. The special handling may include e.g. adjusting/nulling log likelihood ratios for the corresponding RBs which collide with legacy PDSCH allocation according to the resource reservation information provided in the sDCI2.

Figure 7 uses the same initial assumptions as Figure 5, although not show in Figures. That is, the UE is configured by the eNB to the sTTI mode (e.g. the UE is then ready to follow and accept sTTI allocations from the eNB) and is configured to follow common-slow sDCI2 in the PDCCH. Alternatively, the UE may receive the information corresponding to the slow sDCI2 as higher layer signaling/configuration. The UE, depending on when and where the sDCI2 is transmitted to the UE, may also decode the sDCI2 and extract the PDSCH-resource-allocation-information from it.

In Figure 7 it is shown that in step 700 the eNB sets the indication so that the UE should not ignore sDCI2 (and in particular the PDSCH-resource-allocation-in- formation in it). This indication is then included in the sDCIl in step 402 and the sDCIl is then transmitted to the UE in step 404 (similar as in Figure 4). In step 302 of Figure 7 (and of Figure 3) the UE then extracts the indication from the received sDCIl and detects that the UE needs to pay attention to the sDCI2.

The UE continues in step by 704 decoding the sDCI2 as soon as the UE receives the sDCI2 from the eNB (if it has not already received and decoded sDCI2). From the sDCI2, the UE may in step 706 determine which resource blocks are indicated in the resource reservation and then determining that there is at least one overlapping RB in the RBs indicated by the sDCIl and sDCI2. After establishing this, the UE may in step 712 decode the sTTI data by assuming that only those RBs of the sDCIl that do not belong to the at least one overlapping RBs carry sTTI data to the UE.

This is because the eNB, upon setting the indication to indicate that sDCI2 needs to be taken into account the indication in step 700 and sending that indication along with sDCIl to the UE in step 404 of Figure 7, may determine in step 702 the overlapping RBs and that only those RBs of the RBs indicated in the sDCIl that do not belong to the at least one overlapping RB are to be used for carrying sTTI data (i.e. sPDSCH) to the UE. Consequently in step 708 the eNB may send the sTTI data to the UE only in the non-overlapping RBs. Further, the eNB may in step 710 transmit (leg- acy) PDSCH data in the 3 colliding PRBs also in sTTI-2, as shown in Figure 8. As such, the sPDSCH sTTI data may be punctured by the legacy PDSCH data or rate matched around the legacy PDSCH data.

Now, when the indication "sDCI2-ignore-bit" is OFF, as in Figures 7 and 8, there are couple of options on how the decoding takes place, depending on whether puncturing or rate matching is used. This may be based on commonly set basic assumption for the overlapping part. In an embodiment, the commonly agreed specification determines which of those is used. Alternatively or in addition to, this common understanding of which to use may be configured by higher layers or signalled to the UE in sDCIl. Let us look at these by referring to Figure 9, which show different options for blocks 703 and 712 of Figure 7.

In one embodiment, puncturing of the 3PRBs of the sTTI data with legacy data (= the data transmitted in the legacy PDSCH part of the Figure) is applied. In such case the eNB decides to transmit only the sPDSCH RBs that are non-overlapping with the RBs or REs indicated in the sDCI2 PDSCH-resource-allocation-information. This means that the eNB may in step 900 replace the sTTI data at the overlapping PRB with PDSCH (legacy) data. Figure 10 shows how puncturing affects the sTTI data PRBs. It can be seen that sTTI data on PRB#N+1 will not be sent but PDSCH legacy data will take the place. The eNB may also in an embodiment decide to lower the modulation and coding scheme (MCS) for the sPDSCH to compensate for the punctured RBs.

The UE on the receiving side in this example may decode the data based on an assumption that the eNB has punctured the sTTI data at the overlapping RBs. I.e. the UE may assume that RBs intersecting between PDSCH-resource-allocation-infor- mation in the sDCI2 and own resource allocation information in the sDCIl are not used for sPDSCH sTTI data transmission for the UE.

For the decoding, the UE needs to determine TBS and resource mapping. Knowing that puncturing (where overlapping sTTI data is replaced with legacy data) is in use by the eNB, the UE may in step 904 include the at least one overlapping RB (i.e. use the resource allocation from sDCIl) when determining resource mapping and/or TBS determination for the sTTI data, and apply those TBS determination and resource mapping for the decoding. E.g. if there are three overlapping RBs, all of these three RBs are included when determining resource mapping and/or TBS determina- tion for the sTTI data.

Further, in an embodiment, the UE may in step 906 adjust the log-likelihood ratio (LLR) for the at least one overlapping RB for decoding the sTTI data. In an embodiment, this may denote that the UE sets LLRs for symbols in colliding RBs substantially to zero. Finally, the UE may in step 908 of Figure 9 extract the sTTI data by performing the decoding with adjusted LLRs.

Then for the rate matching shown as another possible implementation option in Figure 9, the eNB may, as shown with reference numeral 902, shift the sTTI data at the location of the overlapping PRBs to the next available sTTI PRB. This is also shown for simplicity in Figure 10. For example, if the UE is based on sDCIl expecting three PRBs of sTTI data marked with PRB #N to PRB #N+2, the actually transmitted PRBs is two, since there is no room in the sDCIl allocation to send the last PRB #N+2. So only the sPDSCH resource blocks mapped according to the sDCIl that are non-overlapping with the RBs indicated in the sDCI2 PDSCH-resource-allocation-information are transmitted to the UE.

Therefore, the UE may decode the sTTI data based on an assumption that the transmitting device has mapped the sTTI data around the at least one overlapping RB. This may mean in the rate matching scenario that the US in step 910 excludes the at least one overlapping RB when determining resource mapping and/or TBS for the sTTI data - only the non-overlapping PRBs between the resource allocation in the sDCIl and the legacy resource reservation in the sDCI2 are used to define the TBS. This is because the UE knows that in rate matching the overlapping RB is not used for sTTI data at all, but the sTTI data is rate matched around the overlapping PRB, which may possibly lead in resizing the initial TBS (based on sDCIl alone) of the TTI data. In other words, the resource reservation given in sDCIl and the sDCI2 (e.g. the PDSCH- resource-allocation-information) jointly define the TBS to be used in decoding.

Finally the UE can extract the user data from the sTTI data based on decod- ing the sPDSCH according to the described TBS and resource mapping assumption. Since the rate matching causes the UE not to decode the overlapping RBs, there is no need in rate matching for the UE to adjust the LLRs.

In an embodiment where the UE receives an indication to take sDCI2 into account but where the UE fails to successfully decode the sDCI2 or the sDCI2 is miss- ing, the UE may then be aware that the sTTI data resource mapping according to sDCIl may or may not be fully accurate but it may not be aware how the UE should change the resource mapping. E.g. the UE does not know which RBs of the sPDSCH allocation are possibly overlapping with e.g. legacy PDSCH allocation. Assuming puncturing is used, the TBS and resource mapping are defined based on sDCIl and in this case the sTTI data resource mapping is correct. However, for the case of rate matching, the UE needs to successfully decode the sDCI2, so in such case the TBS and resource mapping determination may fail in case of missing the sDCI2.

In such case, the process may continue as shown in Figure 11. After failing to decode or missing sDCI2 in step 1100, the UE may as one option in step 1102 try to blindly detect the frequency resources by observing the LLRs in sub-bands and determine, which sub-bands have lower LLRs. This is possible e.g. if modulation order of PDSCH is different from modulation order of sPDSCH. Therefore, it may be that the eNB applies different modulation order for the sets of data meant for different recipients, e.g. apply different modulation for PDSCH and sPDSCH. The UE (receiver) may then monitor aspects related to modulation of the received data and then determine which RBs are meant for it and which are not. With this process the UE may determine which of the RBs indicated for the sTTI data in the sDCIl are overlapped with another data, such as legacy PDSCH. In case of rate-matching (TBS size depends on sDCIl and sDCI2) a UE would need to blind detect all the overlapping RBs in order to be able receive the TB successfully, as the TBS determination and the sPDSCH resource mapping is affected by the overlapping resources. On the other hand, in case of puncturing (TBS size depends only on sDCIl), the more overlapping RBs are blindly detected by the UE, the higher the probability is for the successful detection. In general, for the case of puncturing, the UE may not even need to try to identify the overlapping resources and still be able to successfully decode the sPDSCH as neither the TBS size determination nor the sPDSCH resource element mapping is depending on the correct reception of sDCI2.

As another option, the UE may in step 1104 try to decode the sPDSCH anyway assuming all the RBs indicated in the sDCIl being available. Instead of mapping (i.e. rate-matching) sTTI-UE's sPDSCH around the legacy PDSCH, the baseline operation may be to assume all scheduled sPDSCH resources are available for sPDSCH trans- mission, as has been described above in connection of the puncturing. This means that the TBS determination as well as the sPDSCH resource mapping are performed assuming all scheduled 24 PRBs are used for sPDSCH transmission (as in the case of puncturing). This avoids the issue of having a different understanding of the available resources between eNB and UE in case the sTTI UE misses the sDCI2 (containing the PDSCH resource allocation). This may be beneficial because even if the sTTI UE does not receive the DCI2 in case puncturing is applied, there is still a probability for successful reception, especially when overlap with a legacy UE allocation is not severe.

Thus, it can be said that in an embodiment the UE determines resource mapping and/or TBS for the sTTI correctly based on whether or not the sDCI2 is suc- cessfully decoded or not. In case sDCI2 needs to be decoded and rate matching is used, the TBS may need resizing, wherein the new TBS is determined jointly based on sDCIl and sDCI2. In case the sDCI2 needs to be decoded and puncturing is used, then the initial TBS size based on sDCIl holds. This may also be a default operation, since with puncturing the UE still have changes to decode the sTTI data successfully (even when failing to decode sDCI2) while with rate matching the sDCI2 needs to be captured successfully to enable successful decoding of sTTI data. In case of unsuccessful decoding of the sDCI2, the default operation (as in puncturing) may be used. It may be noted that the default operation corresponds to the determining the TBS and the resource mapping based on sDCIl only, i.e. independently of the sDCI2. Therefore, in an embod- iment, the UE and the eNB may both apply a default operation for determining TBS and/or resource mapping, wherein the default operation assumes all RBs indicated in the sDCIl are available for sTTI data and the default mode is known by both the UE and the eNB. E.g. when eNB is transmitting the sTTI data to the receiving device in case there is overlap (as in Figure 8), the eNB may apply puncturing or rate matching for the part of the overlap. The eNB may perform transmission block size determination and resource mapping for the sTTI data based on which one of these (puncturing or rate matching) is used, before transmitting the data to the UE. In one embodiment, the eNB applies the default operation of puncturing, to increase the likelihood of correct decoding by the UE (which may also apply the default assumption of puncturing).

The proposed embodiments may have several advantages. E.g. an advantage of the proposed eNB and UE behaviour may include that a delay tolerant UE, which misses the slow DCI, can still receive the short PDSCH. The solution may give the eNB an opportunity to select the best possible MCS for the short PDSCH given the UE's geometry and/or reported CQI, slow-DCI aggregation level (i.e. the amount of radio allocations in the subframe), and/or the degree of short PDSCH and legacy PDSCH collision (partial/full). The solution further gives the eNB an opportunity to select to prioritize either the short PDSCH (e.g. needed for URLLC, when low-latency traffic need to be extremely reliable), or to improve the multiplexing efficiency of legacy PDSCH with short PDSCH (e.g. when traffic requires low latency but not high reliability, such as slow-start TCP traffic.

An embodiment, as shown in Figure 12, provides an apparatus 10 compris- ing a control circuitry (CTRL) 12, such as at least one processor, and at least one memory 14 including a computer program code (PROG), wherein the at least one memory and the computer program code (PROG), are configured, with the at least one processor, to cause the apparatus to carry out any one of the above-described processes. The memory may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

In an embodiment, the apparatus 10 may comprise the receiving device discussed above, such as a terminal device of a cellular communication system, e.g. a user equipment (UE), a user terminal (UT), a computer (PC), a laptop, a tabloid computer, a cellular phone, a mobile phone, a communicator, a smart phone, a palm computer, or any other communication apparatus. Alternatively, the apparatus 10 is comprised in such a terminal device. Further, the apparatus 10 may be or comprise a module (to be attached to the UE) providing connectivity, such as a plug-in unit, an "USB dongle", or any other kind of unit. The unit may be installed either inside the UE or attached to the UE with a connector or even wirelessly. In an embodiment the apparatus is or is comprised in the UE 120.

The apparatus 10 may further comprise communication interface (TRX) 16 comprising hardware and/or software for realizing communication connectivity ac- cording to one or more communication protocols. The TRX may provide the apparatus with communication capabilities to access the radio access network, for example.

The apparatus 10 may also comprise a user interface 18 comprising, for ex- ample, at least one keypad, a microphone, a touch display, a display, a speaker, etc. The user interface may be used to control the apparatus by the user.

The control circuitry 10 may comprise an extracting circuitry 20 for extracting the indication from the received resource allocation message, according to any of the embodiments. The control circuitry 10 may comprise a decoding circuitry 22 for decoding the sTTI data, according to any of the embodiments. The decoding circuitry may also be responsible of determining the TBS and resource mapping for the decoding, according to any of the embodiments.

An embodiment, as shown in Figure 13, provides an apparatus 50 compris- ing a control circuitry (CTRL) 52, such as at least one processor, and at least one memory 54 including a computer program code (PROG), wherein the at least one memory and the computer program code (PROG), are configured, with the at least one processor, to cause the apparatus to carry out any one of the above-described processes. The memory may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

In an embodiment, the apparatus 50 may be or be comprised in the transmitting device described above, such as in a base station (also called a base transceiver station, a Node B, a radio network controller, or an evolved Node B, for example). In an embodiment the apparatus is or is comprised in the eNB 110.

The apparatus 50 may further comprise communication interface (TRX) 56 comprising hardware and/or software for realizing communication connectivity according to one or more communication protocols. The TRX may provide the apparatus with communication capabilities to access the radio access network, for example.

The control circuitry 52 may comprise an indication determination circuitry 60 for determining/setting and including the indication to the resource allocation message, according to any of the embodiments. The control circuitry may comprise an encoding circuitry 62 for coding and causing transmission of the resource al- location message to the UE, according to any of the embodiments.

In an embodiment at least some of the functionalities of the apparatus of Figure 13 may be shared between two physically separate devices forming one operational entity. Therefore, the apparatus may be seen to depict the operational entity comprising one or more physically separate devices for executing at least some of the described processes. The apparatus utilizing such shared architecture, may comprise a remote control unit (RCU), such as a host computer or a server computer, operatively coupled (e.g. via a wireless or wired network) to a remote radio head (RRH) located in the base station. In an embodiment, at least some of the described processes may be performed by the RCU. In an embodiment, the execution of at least some of the described processes may be shared among the RRH and the RCU.

In an embodiment, the RCU may generate a virtual network through which the RCU communicates with the RRH. In general, virtual networking may involve a process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization may involve platform virtualization, often combined with resource virtualization. Network virtualization may be categorized as external virtual network- ing which combines many networks, or parts of net- works, into the server computer or the host computer (i.e. to the RCU). External network virtualization is targeted to optimized network sharing. Another category is internal virtual networking which provides network-like functionality to the software containers on a single system. Virtual networking may also be used for testing the terminal device.

In an embodiment, the virtual network may provide flexible distribution of operations between the RRH and the RCU. In practice, any digital signal processing task may be performed in either the RRH or the RCU and the boundary where the responsibility is shifted between the RRH and the RCU may be selected according to implementation.

In an embodiment, an apparatus carrying out at least some of the embodiments described comprises at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to carry out the functionalities according to any one of the embodiments described. Ac- cording to an aspect, when the at least one processor executes the computer program code, the computer program code causes the apparatus to carry out the functionalities according to any one of the embodiments described. According to another embodiment, the apparatus carrying out at least some of the embodiments comprises the at least one processor and at least one memory including a computer program code, wherein the at least one processor and the computer program code perform at least some of the functionalities according to any one of the embodiments described. Accordingly, the at least one processor, the memory, and the computer program code may form processing means for carrying out at least some of the embodiments described. According to yet another embodiment, the apparatus carrying out at least some of the embodiments comprises a circuitry including at least one processor and at least one memory including computer program code. When activated, the circuitry causes the apparatus to perform the at least some of the functionalities according to any one of the embodiments described.

As used in this application, the term 'circuitry' refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of circuits and soft-ware (and/or firm- ware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processors/software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term in this application. As a further example, as used in this application, the term 'circuitry' would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and/or firmware. The term 'circuitry' would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

In an embodiment, at least some of the processes described may be carried out by an apparatus comprising corresponding means for carrying out at least some of the described processes. Some example means for carrying out the processes may include at least one of the following: detector, processor (including dual-core and multiple-core processors), digital signal processor, controller, receiver, transmitter, encoder, decoder, memory, RAM, ROM, software, firmware, display, user interface, display circuitry, user interface circuitry, user interface software, display software, circuit, antenna, antenna circuitry, and circuitry.

The techniques and methods described herein may be implemented by various means. For example, these techniques may be implemented in hard-ware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of embodi- ments may be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions de-scribed herein, or a combination thereof. For firmware or software, the implementation can be carried out through modules of at least one chip set (e.g. procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory unit and executed by processors. The memory unit may be implemented within the processor or externally to the processor. In the latter case, it can be communicatively coupled to the processor via various means, as is known in the art. Additionally, the components of the systems described herein may be rearranged and/or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise con-figurations set forth in the given figures, as will be appreciated by one skilled in the art.

Embodiments as described may also be carried out in the form of a computer process defined by a computer program or portions thereof. Embodiments de- scribed may be carried out by executing at least one portion of a computer program comprising corresponding instructions. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer program distribution medium readable by a computer or a processor. The computer program medium may be, for example but not limited to, a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package, for ex-ample. The computer program medium may be a non-transitory medium. Coding of software for carrying out the embodiments as shown and described is well within the scope of a person of ordinary skill in the art.

Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.

Claims

1. A method, comprising:

receiving, by a receiving device from a transmitting device, a resource allocation for short transmission time interval, sTTI, data, wherein the sTTI data is sched- uled according to short transmission time intervals to the receiving device;

extracting from the resource allocation an indication on whether or not a resource reservation for regular transmission time intervals needs to be taken into account or not; and

decoding the sTTI data at least partly based on the indication.

2. The method of claim 1, further comprising:

determining from the indication that the resource reservation need not be taken into account;

determining that each resource block indicated in the resource allocation carries sTTI data to the receiving device; and

decoding the sTTI data by assuming that each of the resource elements indicated in the resource allocation carries sTTI data to the receiving device.

3. The method of claim 1, further comprising:

determining from the indication that the resource reservation needs to be taken into account;

receiving and attempting to decode the resource reservation; determining which resource blocks are indicated in the resource reservation;

determining at least one overlapping resource block between the resource allocation and the resource reservation; and

decoding the sTTI data by assuming that only those resource blocks of the resource allocation that do not belong to the at least one overlapping resource block carry sTTI data to the receiving terminal.

4. The method of claim 3, further comprising:

decoding the sTTI data based on an assumption that the transmitting device has mapped sTTI data around the at least one overlapping resource block.

5. The method of claim 4, further comprising:

excluding the at least one overlapping resource block when determining resource mapping and/or transport block size for the sTTI data.

6. The method of claim 3, further comprising:

decoding the sTTI data based on an assumption that the transmitting device has punctured the sTTI data at the overlapping resource blocks.

7. The method of claim 6, further comprising:

including the at least one overlapping resource block when determining resource mapping and/or transport block size for the sTTI data.

8. The method of any of claims 6 to 7, further comprising:

adjusting the log-likelihood ratio for the at least one overlapping resource block before decoding the sTTI data.

9. The method of any of claim 3, further comprising:

upon failing to successfully decode the resource reservation, applying a default operation to determine resource mapping and/or transport block size for the sTTI data, wherein the default operation assumes all resource blocks indicated in the resource allocation are available for carrying the sTTI data, and wherein the default operation is common to the receiving device and to the transmitting device.

10. The method of any of claims 1 to 9, wherein the resource reservation allocates data that is to be transmitted in the same subframe as the sTTI data.

11. The method of any of claims 1 to 10, wherein the transmission time in- terval of each short transmission time interval is shorter than the regular transmission time interval.

12. A method, comprising:

determining, by a transmitting device, an indication indicating whether or not a resource reservation for regular transmission time intervals needs to be taken into account or not;

including the indication in a resource allocation for short transmission time interval, sTTI, data, wherein the sTTI data is scheduled according to short transmission time intervals to a receiving device;

transmitting the resource allocation including the indication to the receiving device; and transmitting the sTTI data at least partly based on the indication to the receiving device.

13. The method of claim 12, further comprising:

determining the indication at least partly based on whether or not the resource reservation indicates at least one resource block that is at least partially overlapping with at least one resource block indicated in the resource allocation.

14. The method of any of claims 12 to 13, further comprising: upon setting the indication to indicate that the resource reservation need not be taken into account, determining that each resource block indicated in the resource allocation is to be used for carrying sTTI data to the receiving device; and

transmitting the sTTI data to the receiving device based on the determination.

15. The method of any of claims 12 to 13, further comprising: upon setting the indication to indicate that the resource reservation needs to be taken into account, determining at least one overlapping resource block between the resource allocation and the resource reservation;

determining that only those resource blocks of the resource allocation that do not belong to the at least one overlapping resource block are to be used for carrying the sTTI data to the receiving terminal; and

transmitting the sTTI data to the receiving device based on the determination.

16. The method of claim 15, further comprising:

applying a default operation to determine resource mapping and/or transport block size for the sTTI data, wherein the default operation assumes all resource blocks indicated in the resource allocation are available for carrying the sTTI data, and wherein the default operation is common to the receiving device and to the transmitting device.

17. An apparatus, comprising:

at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause a receiving device to perform operations comprising: receiving, from a transmitting device, a resource allocation for short transmission time interval, sTTl, data, wherein the sTTl data is scheduled according to short transmission time intervals to the receiving device;

decoding the sTTl data at least partly based on the indication.

18. The apparatus of claim 17, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

determining that each resource block indicated in the resource allocation carries sTTl data to the apparatus; and

decoding the sTTl data by assuming that each of the resource elements indicated in the resource allocation carries sTTl data to the receiving device.

19. The apparatus of claim 17, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

decoding the sTTl data by assuming that only those resource blocks of the resource allocation that do not belong to the at least one overlapping resource block carry sTTl data to the receiving terminal.

20. The apparatus of claim 19, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

decoding the sTTl data based on an assumption that the transmitting device has mapped sTTl data around the at least one overlapping resource block.

21. The apparatus of claim 20, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

22. The apparatus of claim 19, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

23. The apparatus of claim 22, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

24. The apparatus of any of claims 22 to 23, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

25. The apparatus of claim 19, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the receiving device to further perform operations comprising:

upon failing to successfully decode the resource reservation, applying a de- fault operation to determine resource mapping and/or transport block size for the sTTI data, wherein the default operation assumes all resource blocks indicated in the resource allocation are available for carrying the sTTI data, and wherein the default operation is common to the receiving device and to the transmitting device.

26. The apparatus of any of claims 17 to 25, wherein the resource reservation allocates data that is to be transmitted in the same subframe as the sTTI data.

27. The apparatus of any of claims 17 to 26, wherein the transmission time interval of each short transmission time interval is shorter than the regular transmission time interval.

28. The apparatus of any of claims 17 to 27, wherein the receiving device is a user terminal operating in a cellular communication network.

29. An apparatus, comprising:

at least one processor and at least one memory including a computer pro- gram code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause a transmitting device to perform operations comprising:

determining an indication indicating whether or not a resource reservation for regular transmission time intervals needs to be taken into account or not;

transmitting the resource allocation including the indication to the receiving device; and

transmitting the sTTI data at least partly based on the indication to the receiving device.

30. The apparatus of claim 29, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the transmitting device to further perform operations comprising:

31. The apparatus of any of claims 29 to 30, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the transmitting device to further perform operations comprising:

upon setting the indication to indicate that the resource reservation need not be taken into account, determining that each resource block indicated in the re- source allocation is to be used for carrying sTTI data to the receiving device; and

transmitting the sTTI data to the receiving device based on the determination.

32. The apparatus of any of claims 29 to 30, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the transmitting device to further perform operations comprising:

upon setting the indication to indicate that the resource reservation needs to be taken into account, determining at least one overlapping resource block between the resource allocation and the resource reservation;

transmitting the sTTI data to the receiving device based on the determination.

33. The apparatus of claim 32, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the transmitting device to further perform operations comprising:

34. The apparatus of any of claims 29 to 33, wherein the transmitting device is an access point operating in a cellular communication network.

35. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into an apparatus, execute the method according to any of claims 1 to 16.

36. A computer program product comprising program instructions which, when loaded into an apparatus, execute the method according to any of claims 1 to 16

37. An apparatus, comprising means for performing the method according to any of claims 1 to 16.

38. The apparatus according to claim 37, wherein the apparatus comprises at least one processor; and at least one memory comprising computer program code, and wherein the at least one memory and the computer program code are configured, with the at least one processor to cause the apparatus to provide said means.