Patent ID: 12231375

DETAILED DESCRIPTION OF THE INVENTION

In the following, examples and embodiments of the present invention will be described with reference to the appended Figures. Equal or equivalent elements or elements with equal or equivalent functionality may be denoted in the following description by equal or equivalent reference numerals.

The following description starts with an introductory portion followed by different sections in which the examples and embodiments of the present invention will be described in detail.

1. TDD DL-UL Configurations

In the following, various aspects of the present application, and embodiments thereof, are described. The following description starts with an aspect of the present application according to which data transmission latency is reduced by aggregating TDD carriers having different temporal distribution of uplink times and downlink times. The description starts with embodiments which achieve the difference in temporal distribution of uplink and downlink times by shifting otherwise identical frame configurations of the aggregated TDD carriers. Later on, embodiments follow which efficiently achieve data transmission latency reduction by extending the supported set of frame configurations so as to comprise pairs of ‘inverse’ frame configurations. Subsequently, embodiments are presented which more generally cover the aspect of these embodiments. Subsequently, further aspects of the present application are described in a similar manner.

Generally speaking, using carrier aggregation in TDD operation with different UL-DL configurations on the multiple carriers could help supporting an accelerated and continuous data flow for both UL and DL while simultaneously benefiting from the extended bandwidth.

In case multiple cells with different UL-DL configurations in the current radio frame are aggregated and the UE is not capable of simultaneous reception and transmission in the aggregated cells (not full duplex capable using aggregated carriers), the following constraints may apply:if the subframe in the primary cell is a downlink subframe, the UE shall not transmit any signal or channel on a secondary cell in the same subframeif the subframe in the primary cell is an uplink subframe, the UE is not expected to receive any downlink transmissions on a secondary cell in the same subframeif the subframe in the primary cell is a special subframe and the same subframe in a secondary cell is a downlink subframe, the UE is not expected to receive Physical Downlink Shared Channel (PDSCH), Enhanced Physical Downlink Control Channel (EPDCCH), Physical Multicast Channel (PMCH), or Positioning Reference Signal (PRS) transmissions in the secondary cell in the same subframe, and the UE is not expected to receive any other signals on the secondary cell in OFDM symbols that overlaps with the guard period or UpPTS in the primary cell.
2. Overview of Aspects and Embodiments of the Inventive Concept

For ease of understanding, the following description is divided into individual sections, each of which concerns one or more aspects, examples and embodiments of the present invention:Section 2.1: Fast UL/DL switching on subframe (TTI) level by TDD carrier aggregationSection 2.1.1: Enhancements with TDD UL/DL configurations and subframe shifting on aggregated TDD carriersSection 2.1.2: Distributed operation for TDD carrier aggregationSection 2.1.2.1: U-plane and C-plane splitting conceptSection 2.1.2.2: Bridging transitions between neighboring cellsSection 2.1.2.3: Different carrier frequenciesSection 2.1.2.4: Different beams transmitted from the same base station operated at different TDD UL-DL configurationsSection 2.1.2.5: component carriers operating on a different TTI basis (e.g. sTTI vs. TTI)Section 2.1.3: Enhancements with inverted TDD UL/DL configurations on aggregated TDD carrierssection 2.1.3.1: TDD UL-DL configuration examples with new UL-DL special subframeSection 2.1.4: Interference mitigation between time-shifted aggregated TDD carriers operating in neighbor bandsSection 2.1.4.1: Blanking of outer subbandsSection 2.1.4.2 Interference cancellation techniquesSection 2.1.5: Further EmbodimentsSection 2.2: Accelerated UL and/or DL access through time-offsets within TTI length for aggregated carriers (FDD/TDD-independent)Section 2.2.1: Externally triggered clock for base stationSection 2.2.1.1: Adjust clock of base station by time offsetSection 2.2.1.2: Set idle time for arbitrary system clocksSection 2.2.1.3: Incorporate timing advanceSection 2.2.1.4: Support of multi-stage application cyclesSection 2.2.2: Time-offsets only for a set of physical layer channels on aggregated carriersSection 2.2.3: Further embodimentsSection 2.3: Extended dual TDD operation using multiple (e.g. two or more) antennas with carrier aggregation and inverted switching points
2.1. Fast UL/DL Switching on Subframe (TTI) Level by TDD Carrier Aggregation

One possibility to reduce data transmission latency by providing (almost) continuous UL and/or DL transmission is to use carrier aggregation (CA) where CCs with different TDD UL-DL configurations being time-shifted are established in CA mode.

The UL-DL configurations are selected in such a way that a desired UL/DL ratio is obtained and (almost) continuous transmission is kept. In a more particular manner, carrier aggregation may be performed in the following way where(i) CCs utilize the same supported TDD band UL-DL configurations being time-shifted on the basis of a subframe or TTI lengths, or(ii) CCs utilize TDD bands with different and complimentary UL-DL configurations which are introduced below.

If a CC may switch the TDD UL-DL configuration, the transition between the two configurations can be simply be executed as in the default procedure described in [6,7].

However, an adjustment of the shift of the secondary CCs to the anchor CC can be advantageous to optimize the overall UL/DL ratio in respect to the continuous transmission. In this case, a temporary evacuation may help to set up the corresponding shift.

The concepts described below may also be applicable for TTIs different to subframe basis, e.g. sTTI.

2.1.1 Enhancements with TDD UL/DL Configurations and Subframe Shifting on Aggregated TDD Carriers Such as TDD UL/DL Configurations Currently Existing in LTE

To achieve continuous or almost continuous UL and/or DL transmissions, CA with two or more LTE TDD carriers may be used.

InFIG.2, two legacy compatible TDD carriers C1, C2with the same TDD UL-DL configuration (here configuration 1 of Table 1) are used. That is,FIG.2shows the spectrotemporal distribution of uplink and downlink resources to aggregated component carriers C1and C2one on top of the other. For both component carriers C1and C2, a two-dimensional graph spanned by a time axis t horizontally and a frequency axis f vertically are depicted, and the time axes are registered to each other so that a certain time instant in the graph concerning component carrier C1coincides with the time instant at the same horizontal position exactly below in the graph concerning component carrier C2.

As can be seen, both component carriers C1and C2are of the same frame configuration, with the frames, however, of component carrier C1being temporally shifted with respect to the frames of component carrier C2by two subframes.

In particular,FIG.2exemplarily shows a temporal portion exactly corresponding to one frame10ofFIG.1although it is clear and illustrated at the left-hand and right-hand sides inFIG.2by dotted lines that corresponding frames precede and succeed frame10of component carrier1as depicted.

According to the frame configuration of frame10of component carrier C1, this frame10is sub-divided into ten subframes indicated with #0 to #9. To be more precise, the frame configuration depicted inFIG.2corresponds to the frame configuration described above with respect to Table 1 andFIG.1. That is, the frame configuration is here exemplarily corresponding to LTE, but it should be clear that embodiments of the present application are not restricted to this sort of configuration.

To be even more precise, the temporal sub-division of frame10into subframes #0 to #9 corresponds to frame configuration ‘1’ of Table 1 with arrows within spectrotemporal tiles, i.e. the rectangles inFIG.2, pointing downwards, corresponding to carrier communication resources dedicated to downlink, while an arrow pointing upward indicates communication resources reserved for uplink transmissions.

Accordingly, frame10of component carrier C1is temporarily sub-divided into a sequence of ten subframes #0 to #9 sequentially associated with (in consecutive order from left to right): downlink (#0), special subframe (#1), uplink (#2), uplink (#3), downlink (#4), downlink (#5), special subframe (#6), uplink (#7), uplink (#8) and downlink (#9).

The spectral (i.e. vertical) sub-division into four spectral regions depicted inFIG.2serves for illustration purposes only and is of no special interest here. Component carrier C2is shifted by two subframes relative to component carrier C1. That is, the framing of component carrier C2is shifted by time shift12relative to the framing of component carrier C1. The frames14of component carrier C2are the same frame configuration as frames10of component carrier C1.

Due to the relative temporal shift12between frames10of component carrier C1and frames14of component carrier C2which is, in case ofFIG.2, two subframes long, the uplink subframes or phases of component carrier C2align with the downlink subframes or phases of component carrier C1.

Other shifting offsets12might be used as well although the alignment depicted inFIG.2results into a more complementary assignment of downlink and uplink phases, thereby achieving a better reduction of data transmission latency: whenever data is to be transmitted in an uplink direction, either one of component carrier C1and component carrier C2has an uplink opportunity as either one of component carriers C2and C1has, for each temporal occasion, one of an uplink subframe or special subframe, wherein said special subframes may comprise both downlink and uplink resources, namely before and after the guard period, respectively.

Note that while both carriers C1and C2are individually legacy compatible/backward compatible, i.e. a legacy UE can connect to either one of the carriers C1and C2, carrier aggregation with legacy UEs may currently not be fully supported by LTE as aggregated CCs may need to be synchronized (which may not be the case when they are shifted).

Subframe shifting on aggregated carriers, such as C1and C2ofFIG.2, may be beneficial as certain subframes, such as subframes #0, #1, #5 and #6, may be associated with DL or may contain DwPTS as for the special subframe ‘S’ due to legacy restrictions according to which, e.g. subframes #0, #1, #5 and #6 may contain the PSS and SSS. This allows legacy devices to access each carrier independently while giving devices following the above described use of shifted carrier aggregation, as shown inFIG.2, a constant connectivity in UL and DL.

The above example has been described with respect to the example of the uplink direction transmission but the same may apply when considering downlink transmissions.

FIG.3shows one example of configuring constant DL and almost constant UL connectivity using three shifted component carriers CC1, CC2and CC3, thereby indicating that the aggregation of two CCs has been presented so far merely as an representative example, and that the number of aggregated carriers may be chosen freely to be greater than one.

The subframe sub-division of the individual component carriers is depicted inFIG.3in a manner similar toFIG.2but with simplifying the illustration by merely showing the temporal sub-division of the frames into subframes #0 to #9 and omitting any spectral divisioning.

Component carriers CC1, CC2and CC3are depicted inFIG.3one on top of the other with a temporal axis extending horizontally and a frequency axis extending vertically just as it has been the case inFIG.2, the axes being registered to each other as far as component carrier CC1to CC3is concerned, and the subframes being named by its subframe position within the corresponding frame, i.e. by subframe index #0 to #9.

Subframes #0 to #9 may be associated with at least one of downlink, uplink and special subframes using the ‘D’, ‘U’ and ‘S’ abbreviations as explained above with respect to Table 1.

As can be seen, component carriers CC1to CC3ofFIG.3are all of the same frame configuration which, in the exemplary case ofFIG.3, corresponds to frame configuration number 3 of Table 1.

The temporal shift12between component carriers CC2and CC1is three subframes long, with the frames of component carrier CC2being denoted with reference numeral14. The corresponding temporal shift12′ of component carrier CC3relative to CC1is six subframes long with the frames of component carrier CC3being denoted with reference numeral14′.

While the example for aggregating time-shifted component carriers may be exploited for TDD carriers of frame configurations used today, it would be possible to define future UE categories which may support shifted CCs to include this concept into LTE such as into LTE advanced.

2.1.2 Distributed Operation for TDD Carrier Aggregation

In the following it will be discussed how to operate small cells with different TDD DL/UL configurations similar to the description in section 2.1.1 above. It is identified which cell is transmitting the anchor carrier, while the other cells are transmitting the other component carrier, which is potentially newly defined as described above.

2.1.2.1 U-Plane and C-Plane Splitting Concept

An U-plane and C-plane splitting concept may be used so as to introduce a level of coordination to organize the data flow for the anchor and component carriers. Two options are available to operate the different component carriers:slightly shifted as described in section 2.1.1 but transmitted from different locations, and/orboth component carriers are operated at the same frequency band and transmitted from different infrastructure locations.
2.1.2.2 Bridging Transitions Between Neighboring Cells

The TDD UL/DL configurations of the selected cells, which might be a macro-, small-, pico- or femto-cell, may be organized such that a seamless handover may be guaranteed while maintaining a continuous DL connectivity.

That is, the concept outlined above, namely the one using time-shifted component carriers, may be used for bridging transitions between neighboring cells. Imagine, for instance, a coverage of a certain area using cells which operate or provide carriers not shifted relative to each other, but secondary or helper cells of potentially smaller coverage are distributed so as to merely cover the edges of the above mentioned primary cells at which the primary cells overlap each other so as to enable a smooth and seamless handover between the primary cells with the secondary cells providing carriers temporarily shifted relative to the primary cells' carriers.

2.1.2.3 Different Carrier Frequencies

The heterogeneous cells may be operated in completely different carrier frequencies such as 1.8 GHz, 2.6 GHz, 28 GHz and 60 GHz. Here, any of the schemes of sections 2.1.2.1 or 2.1.1 may be used.

2.1.2.4 Different Beams Transmitted from the Same Base Station Operated at Different TDD UL-DL Configurations

Different TDD UL/DL configurations may also be assigned to different beams transmitted from one, e.g. the same, base station which, in turn, might be a macro-, small- or pico-cell base station.

For example, different beams transmitted from the same base station may be operated at different TDD UL-DL configurations so that a UE served by such a base station may take advantage of aggregating component carriers assigned to different beams. Operating different TDD UL-DL configurations or different beams transmitted from the same base station may be achieved by having a large set of transmit antennas and allowing full-duplex transmission at the base station.

In each of the transmitted beams, either the same band can be used or the carrier aggregation concept described above may be combined such that full DL/UL connectivity can be maintained over different CCs or beams or both. In this case, CQ and PMI feedback from the users for the different beam and CC combinations might be needed.

2.1.2.5 Component Carriers Operating on a Different TTI Basis (e.g. sTTI Vs. TTI)

The above concept of aggregating component carriers of temporally distinct frame configuration or temporally distinct uplink/downlink temporal distribution may be applied to a case where one of the component carriers is operating on sTTI basis whereas the other component carrier is operating on TTI basis. The TTI basis denotes or pertains to the temporal interval at which the communication resources of the individual carriers are assigned to the various user entities which are communicating via these carriers.

This transmission time interval (TTI) is of high importance as new messages to be sent in a downlink or uplink direction need to be announced in specially reserved resources periodically occurring at the TTI and, accordingly, the longer this TTI is the less favorable the respective carrier is for low latency messages. Smaller TTIs such sTTI (short Transmission Time Interval), allow for an earlier announcement of messages.

Accordingly, C-plane splitting may be done for distributed carrier aggregation on sTTI basis. For sTTI, an interface between different eNBs that is fast enough to coordinate resource allocation on sTTI basis may be needed. In particular, a further C-plane splitting in fast and slow C-plane may be introduced.

For example, inFIG.4a first eNB381or a first base station381, also depicted as ‘eNB1’, communicates with a UE30via an anchor carrier16. For instance, the first base station36‘eNB1’ is a macro cell. This anchor carrier16carries legacy control plane over slow C-plane on TTI basis.

FIG.4depicts the case where anchor carrier16is aggregated with another component carrier18via which UE30is connected with a second eNB382or second base station382, also depicted as eNB2, which might, for instance, be a femto cell.

The active component carrier18may carry component carrier control plane on fast C-plane on sTTI basis. This means the following: eNB1and eNB2are connected via a core network20. If a data packet to be transmitted in downlink direction, for instance, such as packet22, arrives at eNB2, there is no need to announce its transmission to UE30via the PDCCH of anchor carrier16. Rather, it is possible to announce the transmission of packet22via component carrier18at the next occasion occurring at sTTI basis on the component carrier18itself, thereby reducing the data transmission latency.

In other words, it may be favorable to introduce a further C-plane splitting in fast and slow C-Plane. An anchor carrier16(e.g. macro cell) on a first eNB1may carry legacy control plane over slow C-Plane on TTI basis, while an active component carrier18on a second eNB2may carry a component carrier control plane on fast C-Plane on sTTI basis.

2.1.3 Enhancements with Inverted TDD UL/DL Configurations on Aggregated TDD Carriers

In the following, embodiments are described where TDD configurations are designed in a way that an uplink frame in one or more carriers may be matched by at least one downlink frame in another carrier. In other words, extra or new TDD UL/DL configurations with complementary or ‘inverted’ patterns may be introduced in the following.

In order to illustrate the concept, it is referred toFIGS.5and6each showing two aggregated component carriers CC1and CC2one on top of the other.

In particular, in case ofFIGS.5and6, the framing of both component carriers CC1and CC2is the same, i.e. the frames of component carriers CC1and CC2are temporally co-aligned. Accordingly, one common subframe indexing is used inFIGS.5and6for the temporal portion illustrated in these figures. In particular, the temporal portion exemplarily shown inFIGS.5and6is four subframes wide. The depicted subframes are subframes #w, #x, #y and #z within a current frame.

As can be seen, however, the temporal fraction shown inFIGS.5and6reveal that the component carrier CC1and CC2have their subframes associated to uplink and downlink inverse to each other. That is, while a certain subframe (e.g. #x) of component carrier CC1is assigned to uplink, the opposite is true for the co-temporal subframe (e.g. #x) of component carrier CC2.

FIGS.5and6may illustrate the concept of using complementary frame configurations for aggregated component carriers rather in a simplified manner disregarding the existence or necessity for ‘S’ (Special) subframes. In any case, the two schematic examples ofFIGS.5and6obviously allow for continuous and accelerated UL/DL access by use of two different component carriers CC1and CC2with complementary or inverted configurations.

In case of more than two aggregated carriers, the UL/DL ratio to fulfill a given data/service requirement could be adjusted in a flexible way. Two CCs may be sufficient to establish the continuous UL/DL transmission while the other CC(s) leave(s) the option to adjust respective UL and/or DL data rates.

2.1.3.1 TDD UL-DL Configuration Examples with New UL-DL Special Subframe ‘SN’

Further TDD UL-DL configuration examples are set out below. They comprise a new UL-DL special subframe which is denoted as ‘SN’ in the following in order to distinguish such subframes from Uplink subframes ‘U’, Downlink subframes ‘D’ and Special subframes ‘S’, which have been introduced above.

Table 2 shows extended LTE TDD UL-DL configurations. In particular, for each existing UL-DL configuration 0 to 6 as listed in Table 2, a corresponding complementary pattern, denoted with letters A to G, is shown which ensures UL and DL continuity.

Special care may have to be taken to subframes #1 and #6 as they contain the primary synchronization channel P-SCH, i.e. the first OFDM symbols at the beginning of the respective subframe, which need to be transmitted in DL.

Similarly, the secondary synchronization channel S-SCH is located in the last OFDM symbols of subframes #0 and #5, i.e. the end of these subframes may also have to be transmitted in DL.

InFIG.7, the spectrotemporal position or location of P-SCH, carrying PSS, and S-SCH, carrying SSS, for subframes #0 and #1 are shown, wherein SSS is depicted in hatched lines and PSS is depicted in cross-hatched lines.

The above mentioned constraint can be solved by using downlink in the considered subframes or, alternatively, by introducing a new UL-DL special subframe ‘SN’ that can be used in subframes #0 and #5 where just the last symbol, i.e. symbol 6 in slot 1, needs to be downlink, namely for the S-SCH and partial uplink transmission is possible in the first symbols of the subframe, i.e. all symbols of slot 0 and symbols 0 to 5 of slot 1.

TABLE 2Downlink-UL-DLto-Uplinkconfig-Switch-pointSubframe numberurationperiodicity#0#1#2#3#4#5#6#7#8#905 msDSUUUDSUUUASNDDDSSNDDDS15 msDSUUDDSUUDA(best DLSNDDDSSNDDDScomplement)B(best ULSNDDSUSNDDDScomplement)25 msDSUDDDSUDDB(best DLSNDDSUSNDDSUcomplement)C(best ULSNDSUUSNDSUUcomplement)310 msDSUUUDDDDDDSNDDDSSNSUUU410 msDSUUDDDDDDD(best DLSNDDDSSNSUUUcomplement)E(best ULSNDDSUSNSUUUcomplement)510 msDSUDDDDDDDE(best DLSNDDSUSNSUUUcomplement)F(best ULSNDSUUSNSUUUcomplement)65 msDSUUUDSUUDA(best DLSNDDDSSNDDDScomplement)G(best ULSNDDDSSNDDSUcomplement)
2.1.4 Interference Mitigation Between Time-Shifted Aggregated TDD Carriers Operating in Neighbor Bands

For neighboring aggregated TDD carriers, DL-UL misalignment might lead to interference. In particular, the DL carrier transmits with much higher output power which can lead to a high interference to the UEs transmitting in a neighboring uplink with a much lower transmit power. However, if the operation mode with time-shifted TDD of neighboring frequency bands is configured, several interference mitigation techniques might be used to overcome this interference. Some of these possibilities are set out below.

2.1.4.1 Blanking of Outer Subbands

For example, “outer” radio resources/subbands of the frequency band within the aggregated CC could be blanked. In other words, the scheduler may not allocate resources to the “outer” PRBs (Physical Resource Blocks) in the considered subframes or radioframe.

This could be exploited by using a configuration interface provided for the scheduler, as well as by use of a remote configuration interface between neighboring eNBs or small cells using the X2 interface.

FIG.8shows an example wherein two aggregated component carriers CC1and CC2, one on top of the other, using the spectrotemporal illustration previously discussed with reference toFIG.2with one common temporal axistrunning horizontally being applicable to both component carriers CC1and CC2.

The framing of component carriers CC1and CC2is time-shifted by temporal shift12so that frames14of CC2are time-shifted relative to frames10of CC1.

Likewise, one common frequency axis ‘f’ running vertically is used to relate to both component carrier CC1and component carrier CC2, thereby illustrating the spectral breadth of both component carriers as well as the spectral juxtaposition of both component carriers wherein CC1is spectrally adjacent to CC2at the high frequency side of CC2. That is, CC1and CC2spectrally neighbor each other with the lower frequency side of CC1facing the higher frequency side of CC2. However, this is merely an example and could also be differently, e.g. the other way around.

The left-hand side ofFIG.8shows the situation where the complete spectral width of CC1, i.e. physical resources or radio resources distributed over the complete spectral width of component carrier CC1, are allocated for respective communications, while the right-hand side illustrates the case where the spectral portion at the spectral end of component carrier CC1which neighbors or faces component carrier CC2, is blanked, i.e. is excluded from being allocated. This blanked spectral portion is denoted with reference numeral24.

Accordingly, while physical resources allocated to downlink in the non-blanked case at the left-hand side might lead to interference, denoted by reference numeral26, of respective uplink transmissions via CC2, such interference does not occur in case of the above outlined interference management where the neighboring PRBs are excluded from resource allocation, i.e. where a particular spectral portion24is blanked.

That is,FIG.8shows an example where the outer DL subband on CC1is blanked to avoid interference to the adjacent UL subband on CC2. Blanking of the outer band is just needed at times where UL is active on CC2. Instead of blanking the complete outer subband, it may also be sufficient to blank just certain PRBs.

2.1.4.2 Interference Cancellation Techniques

Simultaneously transmitting and receiving two TDD carriers may lead to interference to the incoming signal. Therefore, interference cancellation techniques might be used to subtract the higher power transmitted signal from the received signal. This might be done in the analogue domain and/or the digital domain.

2.1.5 Further Embodiments

Before proceeding with the description of examples and embodiments of the present invention relating to certain aspects of the present invention, the above description will be briefly summarized by presenting a description of a transceiver using any of the above-described concepts and thoughts in order to gain the advantage also set out above.

FIG.9for instance shows a transceiver30configured to perform wireless data communication with a third party device (not shown) by aggregating time division duplex (TDD) carriers321,322,323which have different temporal distribution of uplink times and downlink times.

The time division duplex (TDD) carriers321,322,323are aggregated into a carrier set32. The set32of aggregated TDD carriers321,322,323is indicated using reference sign32inFIG.9while the individual TDD carriers are denoted321,322and so on, in case of more than two component carriers participating in the aggregation.

The transceiver30shown inFIG.9might be a UE, e.g. a mobile terminal or user entity, using the aggregated set32of TDD carriers321,322,323for communication with a base station (not shown) or base station system (not shown) as the other third party, or transceiver30might be a base station or base station system with using the carrier aggregation for communication with a mobile terminal or UE as the other third party device.

As an outcome of the aggregation, transceiver30is able to use all aggregated component carriers321,322,323for uplink and downlink transmissions. As exemplarily shown inFIG.10, at some point in time to, transceiver30is to transmit something in uplink direction. For this uplink transmission it may use one of the TDD carriers321,322having an uplink phase34at that time instant to such as TDD carrier322in the exemplary case ofFIG.10while using TDD carrier321if a downlink transmission would have to take place at time instant to and this TDD carrier321would comprise a downlink phase at the time index to as illustratively depicted inFIG.10.

As already described above, the TDD carriers321,322,323may have different temporal distribution of uplink times and downlink times. This means, as illustrated with respect toFIG.10, that these TDD carriers321,322,323may have at least several time instances where at least one TDD carrier has an uplink phase whereas at least another TDD carrier of the set32has a downlink phase. Variable t0inFIG.10is such a time instant.

If chosen advantageously, the percentage of time instances where at least one TDD carrier of the set32has an uplink phase whereas at least another one of the set32has a downlink phase is greater than 50%, more advantageously more than 60% and even more advantageously more than 80%. Variable t0inFIG.10illustrates such a time instant with respect to an example of two carriers321,322depicted in a state one upon the other in a temporally, i.e. horizontally, registered manner, with merely a temporal fraction being shown.

The carriers321,322are exemplarily depicted inFIG.10as being temporally subframe-aligned which circumstance is, however, not mandatory. One subframe34for each carrier is exemplarily shown inFIG.10to illustrate this alignment.

As depicted inFIG.2and discussed in sections 2.1.1 and 2.1.3, the TDD carriers321,322-called C1and C2inFIG.2—may be temporally structured into consecutive frames of a frame length which is equal between the TDD carriers321,322, wherein the frames of the TDD carriers321,322may show a temporal alternation between uplink and downlink phases which is equal between the TDD carriers321,322.

That is, the frames may be of the same frame configuration. For example, the depicted (FIG.10) frame of carrier321may be subdivided into subframes34in the same manner as the depicted frame of carrier322, with the sequential association of the subframes34within frames of carriers321and carrier322to downlink and uplink subframes being the same, too.

The mutual temporal shift12may be an integer multiple of a subframe's34length so that the carriers'321,322subframes are temporally aligned even when the frames of the carriers321,322are shifted relative to each other, at least by an integer multiple of the mutual subframe length. InFIG.11, the temporal shift12is denoted as Δt.

It should be noted that the transceiver30depicted inFIG.9may be a base station with the third party device to which wireless data communication is instantiated by carriers321,322,323being a mobile terminal. This possibility is depicted inFIG.12ausing reference sign36for illustrating the third party device as a rectangle which, in turn may represent a mobile device.

The transceiver30is here configured to configure the TDD carriers321,322,323and send configuration signals for correspondingly configuring the TDD carriers321,322,323on the side of the third party device36, to the third party device36via at least one of the TDD carriers321,322,323.

Merely two carriers321and carrier322are depicted inFIG.12afor illustration purposes, but naturally, more than two may be present. This statement shall now be understood as pertaining to all the embodiments specifically discussing the coexistence of two aggregated carriers without explicit repetition.

FIG.12bshows a further example according to which the transceiver30ofFIG.9may be a system comprising at least two base stations381,382(triangles) connected via a backhaul network not further shown inFIG.12b, wherein the third party device36may be a mobile terminal.

The transceiver30of this embodiment may be configured to communicate with the third party device36via a first TDD carrier321at a first base station381and via a second TDD carrier322at a second base station382. The transceiver30configures the first and second TDD carriers321,322and sends configuration signals for correspondingly configuring the first and second TDD carriers321,322at the third party device36, to the third party device36via at least one of the TDD carriers321,322.

The TDD carriers321,322may be aggregated as explained further above. Accordingly, from a base stations point of view, embodiments provide for a base station system30comprising a first base station381and a second base station382. The base station system30of this embodiment is configured to perform wireless communication with a mobile terminal36(e.g. an UE) by aggregating a first carrier321at the first base station381and a second carrier322at the second base station382.

The inventive base station system30of this embodiment is further configured to configure the first and second carriers321,322. The base station system30may do so by sending first configuration signals for correspondingly configuring the first and second carriers321,322at the mobile terminal36, to the mobile terminal36via the first carrier321, and by sending second configuration signals for correspondingly configuring the second carrier322at the mobile terminal36, to the mobile terminal36via the second carrier322. Additionally or alternatively, the base station system30may do so by sending first configuration signals for correspondingly configuring the first and second carriers321,322at the mobile terminal36, to the mobile terminal36via the second carrier322, and by sending second configuration signals for correspondingly configuring the second carrier322at the mobile terminal36, to the mobile terminal36via the first carrier321. Stated in more general terms, the base station system30of this embodiment may be configured to transmit first configuration signals to the mobile terminal via at least one of the component carriers321,322.

Furthermore, the base station system30of this embodiment is configured to send the first configuration signals to the mobile terminal36less frequently than the second configuration signals. In other words, the first base station381uses a slow C-Plane, while the second base station382uses a fast C-Plane. Stated in yet other words, the first carrier321of the first base station381comprises longer TTIs than the second carrier322of the second base station382.

For further details as to the aforementioned C-Planes it is referred toFIG.4.

Stated from a UEs point of view, embodiments of the invention provide for a mobile terminal36configured to perform wireless communication with a base station system30comprising a first base station381and a second base station382by aggregating a first component carrier321at the first base station381and a second component carrier322at the second base station382.

The mobile terminal36of this embodiment is further configured to receive first configuration signals from the base station system30via at least one of the component carriers321,322. It may further be configured to receive second configuration signals from the base station system30via at least the first and/or the second component carrier322.

The mobile terminal36may further be configured to configure the first and second component carriers321,322depending on the first and second configuration signals received by at least one of the first and second component carriers321,322.

Furthermore, the mobile terminal36of this embodiment may be configured to derive the first configuration signals from the first component carrier321less frequently than the second configuration signals from the second component carrier322. In other words, the channel between the mobile terminal36and the first base station381uses a slow C-Plane, while the channel between the mobile terminal and the second base station382uses a fast C-Plane.

According to yet a further embodiment, at least one of the at least two base stations381,382depicted inFIG.12bmay be configured to communicate with the third party device (e.g. UE, mobile terminal, etc.)36, or even with another third party device (not depicted), over a further TDD carrier (e.g. TDD carrier323exemplarily depicted inFIG.9). The further TDD carrier323may be located within a frequency band spectrally adjacent to a frequency band of the first TDD carrier311and/or adjacent to a frequency band of the second TDD carrier322.

Furthermore, the temporal distribution of uplink times and downlink times of said further TDD carrier323may vary from the temporal distribution of the first TDD carrier321and/or of the second TDD carrier322. As described with reference toFIG.8, the transceiver of this example may be configured to blank subcarriers at a frequency subband24at an end of the respective frequency band of the above mentioned further TDD carrier323and/or of the first TDD carrier321and/or of the second TDD carrier322.

According to yet a further embodiment, and as discussed with reference toFIG.4, the transceiver30may send the aforementioned first configuration signals for correspondingly configuring both the first and second TDD carriers321,322at the third party device36, to the third party device36via the first TDD carrier321, while sending second configuration signals merely for correspondingly configuring the second TDD carrier322at the third party device36, to the third party device36via the second TDD carrier322, wherein the first configuration signals might be sent to the third party device36less frequently, for example on TTI basis, than the second configuration signals which may be sent on an sTTI basis.

The configuration may pertain to the scheduling of uplink and/or downlink transmissions on the carriers321,322, respectively.

InFIGS.12aand12bthe third party devices may themselves be transceivers of the type shown inFIG.9, i.e. they may be the transceiver30, with the entity36inFIGS.12aand12bassuming the role of the third party device36, with this being illustrated by the assignment of reference numbers in parentheses.

Thus,FIG.12ashows that the transceiver30ofFIG.9may be the mobile terminal, whereas the third party device36is a base station and the transceiver30is configured to receive configuration signals from the third party device36via at least one of the TDD carriers321,322and configure the TDD carriers321,322on this side depending on the configuration signals.

FIG.12billustrates that the transceiver30ofFIG.9may be a mobile terminal, with the third party device36being a system comprising at least two base stations381,382and a backhaul network not shown inFIG.12b, wherein the transceiver30is configured to communicate with the system36via the first TDD carrier321at the first base station381and via a second TDD carrier322at a second base station381, wherein the transceiver30is configured to receive first configuration signals from the system36via at least one of the TDD carriers321,322and configure the first and second TDD carriers321,322depending on the configuration signals.

As described, first configuration signals sent via, e.g. the first TDD carrier321for configuring both carriers321,322may be sent less frequently than second configuration signals sent via the second TDD carrier322for configuring carrier322specifically.

In both of the embodiments of the transceivers as depicted inFIG.12aandFIG.12b, the first and the second TDD carriers321,322may share the same frequency band.

Furthermore, the configuration signals that have been exemplarily described with reference toFIG.12aandFIG.12bmay comprise, e.g. an user allocation signal for allocating spectrotemporal segments of the TDD carriers321,322to different users, for example to different UEs. Additionally or alternatively, said configuration signals may comprise a frame setting signal for indicating a temporal distribution of uplink times and downlink times within one or more upcoming frames of the TDD carriers321,322.

It may be possible that the transceiver30allows for, and may accordingly perform, a switching between different frame configurations at transitions between immediately consecutive frames34of the TDD carriers321,322so that the temporally overlapping frames34of the TDD carriers321,322are of the equal frame configuration, wherein the different frame configurations differ in temporal alternation between uplink and downlink phases.

For example, at some point in time, the frame configuration which the frames34of TDD carriers321,322are composed of, is changed from one configuration of Table 1 to another of Table 1 although the selection from Table 1 is merely an example.

It could be, however, that such switching is allowed merely in the framework of some reconfiguration or rebooting process of the whole cellular network or system including base station38.

In other words, transceiver30may support different frame configurations out of which the frames34of the first TDD carrier321and the frames34of the second TDD carrier322are selected so that frames34of the first TDD carrier321are of a first frame configuration and the frames34of the second TDD carrier322are of a second frame configuration, namely with the first and second frame configuration being equal to each other according to the example ofFIG.2. Then, the transceiver30may be configured to adapt the amount at which the frames34of the first and the second carriers321,322are temporally shifted to each other depending on the selection of the first and second frame configurations out of the different frame configurations.

In other words, Δt may depend on, or vary depending on, the frame configuration chosen for frames34. InFIG.2, Δt was two subframes long for configuration number 1 of Table 1, but it could be different for another configuration of Table 1, for instance, such as three subframe lengths for configuration number 3.

For further explanation of further embodiments, reference shall again be made to Table 1 in combination withFIG.12c.

As explained further above, Table 1 exemplarily shows seven different UL-DL configurations 0 to 6. These different UL-DL configurations 0 to 6 may also be referred to as a group of frame configurations.FIG.12cshows a less detailed version of Table 1.

Some configurations of the group may comprise the same patterns of uplink and/or downlink and/or special resources which may be contiguous and temporally collocated. For example, the subframes #0, #1 and #2 may comprise ‘D’, ‘S’, ‘U’ in each of the seven configurations within the group. These contiguous and temporally collocated number of subframes may also be referred to as a frame segment1601,1602,1603.

The same applies, for instance, for subframes #5 and #6. With reference to Table 1, subframe #5 uses ‘D’, while subframe #6 either uses ‘S’ or ‘D’. Accordingly, as depicted inFIG.12c, the configurations may also comprise a second frame segment1611,1612,1613having an equal scheduling of uplink and/or downlink and/or special resources.

Embodiments of the present invention may therefore provide for a transceiver, wherein the different frame configurations, between which the transceiver switches, form a group of frame configurations. At least a majority of these frame configurations of said group provides, in one or more contiguous and—relative to the frame borders—temporally collocated frame segments1601,1602,1603,1611,1612,1613, an equal scheduling of uplink and/or downlink.

As mentioned above, the transceiver may switch between these different frame configurations. As exemplarily depicted inFIG.12c, the frames of the first and second TDD carriers CC1and CC2are temporally mutually shifted by a time amount corresponding to a temporal length of the one or more contiguous and—relative to the frame borders—temporally collocated frame segments1611,1612. In the example shown inFIG.12c, the carriers CC1and CC2are shifted by a time amount corresponding to the temporal length of the second frame segment1611,1612comprising subframes #5 and #6, i.e. by a time amount corresponding to the two subframes #5 and #6.

According to yet a further embodiment, the different frame configurations between which the transceiver switches form a group of frame configurations equally subdivided into a sequence of subframes #0 to #6, each subframe #0 to #6 being associated with at least one of an uplink mode ‘U’, a downlink mode ‘D’ and a special mode ‘S’, as mentioned above.

The special mode ‘S’ corresponds to a predetermined below-subframe temporal distribution of uplink ‘U’ and downlink ‘D’. In other words, the special mode ‘S’ may comprise subdivisions of a size smaller than a subframe-size, said subdivisions being exemplarily depicted inFIG.1denoted with ‘DwPTS’, ‘GP’ and ‘UpPTS’.

At least a majority of the group of frame configurations differs in association of the subframes to the uplink mode ‘U’, the downlink mode ‘D’ and the special mode ‘S’ with having one or more contiguous and—relative to the frame borders—temporally collocated frame segments1601,1602,1603,1611,1612,1613within which the subframes' association to the uplink mode ‘U’, the downlink mode ‘D’ and the special mode ‘S’ being such that there is no—with respect to the frame borders—temporally collocated pair of subframes in the one or more contiguous and—relative to the frame borders—temporally collocated frame segments1601,1602,1603,1611,1612,1613, of which one part of the pair is associated with uplink mode while the other part of the pair is associated with the downlink mode ‘D’. In other words, and with reference to Table 1, there is no subframe using downlink mode ‘D’ which is directly followed by a subframe using uplink mode ‘U’.

As exemplarily depicted inFIG.3, according to a first option of this embodiment, the frames of the first and second TDD carriers CC1, CC2(and optionally a third carrier CC3) are mutually shifted by n times a subframe length with n corresponding to the number of subframes the one or more contiguous and—relative to the frame borders—temporally collocated frame segment is long. In this example, the first frame segment1601,1602,1603comprising subframes #0, #1 and #2 is three subframes long. Accordingly, the temporal time shift is also three subframes long.

Still with reference toFIG.3, for example, it can be seen that the frames of the first and second TDD carriers CC1and CC2may be temporally mutually shifted by a time amount corresponding to a temporal length of the above mentioned first frame segment1601,1602,1603comprising subframes #0, #1 and #2. According to this example, the first frame segment comprising subframes #0, #1 and #2, i.e. ‘D’, ‘S’ and ‘U’ is considered. As can be seen, the frame segment #0, #1, #2 of the second component carrier CC2is shifted relative to the frame segment #0, #1, #2 of the first component carrier CC1. Furthermore, the frame segment #0, #1, #2 of the third component carrier CC3is shifted relative to the frame segment #0, #1, #2 of the second component carrier CC2. In other words, the temporal shift equals the number of subframes contained within a frame segment160,161.

As exemplarily depicted inFIG.12c, and according to a second option of this embodiment, the frames of the first and second TDD carriers CC1, CC2(and optionally a third carrier CC3) are mutually shifted by n times a subframe length with n corresponding to the minimum number of subframes which when mutually temporally shifting two instantiations of the one or more contiguous and—relative to the frame boarders—temporally collocated frame segments1601,1602,1603,1611,1612,1613of any of the group of frame configurations, results in an absence of any pair of subframe within a first instantiation and—after temporal shift—temporally collocated subframe within the second instantiation among which both are of the uplink mode, or both of the downlink mode.

In other words, in case of the first frame segment1601,1602,1603containing subframes #0, #1, #2 and/or the second frame segment1611,1612,1613comprising subframes #5 and #6, each of Table 1's configurations may be shifted by two subframes, so that the first and second frame segments do not overlap.

As previously discussed above in section 2.1.4.1 with respect toFIG.8, transceiver30may be a base station which blanks subcarriers at an edge of a frequency band of one or more neighbor carriers being spectrally adjacent to at least one of the TDD carriers321,322,323belonging to the aggregated carrier set32, wherein the neighbor carrier may be another TDD carrier of set32or another carrier via which the base station communicates with one or more further third party devices.

InFIG.8, the blanking took place with respect to CC1at the edge close to CC2, with CC1and CC2belonging to one set of frames14. Alternatively, the first and second TDD carriers321and322may share the same frequency band as discussed in section 2.1.2.1, first alternative, or on different frequency bands as described in section 2.1.1 or section 2.1.2.3.

As described in section 2.1.2.3, the first and second TDD carriers321and322may be on frequency bands separated from each other by more than 5 GHz. Even alternatively or additionally, in case of the transceiver30being a system composed of one or more base stations281,282as discussed above with respect toFIG.12b, at least one of the first and second base stations281,282may communicate via the TDD carrier spectrally neighboring the blanked carrier with the third party device, wherein this base station281,282spatially confines its downlink transmissions over this TDD carrier onto a spatial beam.

The system transceiver30may communicate with another third party device over a further carrier, which may also be a TDD carrier, in a manner spatially confining this communication to a further spatial beam, the further carrier differing in temporal distribution of uplink times and downlink times from the former TDD carrier. This has been discussed in section 2.1.2.4. The two mentioned beam focused carriers may share the same frequency band.

As explained above with reference toFIGS.5and6and Table 2, examples of the present invention provide for inverted frame configurations.

For example, as can be seen in Table 2, a first frame configuration 0 may comprise subframes #0 to #9, each having a certain distribution of uplink mode ‘U’, downlink mode ‘D’ and special mode ‘S’.

A complementary frame configuration may be provided by means of depicted frame configuration A. As can be seen, for each subframe of configuration 0 which contains ‘U’, a complementary subframe containing ‘D’ or ‘S’ is provided in configuration A. Accordingly, the complement of uplink mode ‘U’ is either a subframe of downlink mode ‘D’ or special mode ‘S’.

For each subframe of configuration 0 which contains ‘D’, a complementary subframe containing ‘U’ or ‘SN’ is provided in configuration A. Accordingly, the complement of downlink mode ‘D’ is either a subframe of uplink mode ‘D’ or new special mode ‘SN’.

However, the complement of special mode ‘S’ is downlink mode ‘D’.

Thus, embodiments provide for a transceiver, wherein the TDD carriers are temporally structured into consecutive frames of a frame length which is equal between the TDD carriers, wherein temporally overlapping frames of the TDD carriers are temporally registered to each other to temporally coincide, wherein the transceiver is configured to switch between different frame configurations at transitions between immediately consecutive frames of the TDD carriers (321,322,323), wherein the different frame configurations between which the transceiver (30) switches, form a group of frame configurations equally subdivided into a sequence of subframes, e.g. subframes #0 to #9 in Table 2.

Each subframe #0 to #9 is associated with one of an uplink mode ‘U’, a downlink mode ‘D’ and one or more special modes ‘S’ or ‘SN’, the one or more special modes ‘S’ or ‘SN’ correspond to a predetermined below-subframe temporal distribution of uplink ‘U’ and downlink ‘D’ (seeFIG.1).

As shown in Table 2, the group of frame configurations comprises a first subset of frame configurations, e.g. frame configuration 0 and a second subset of frame configurations, e.g. frame configuration A. The first and second subsets each differ in distribution of, and frequency of, subframes #0 to #9 associated with the uplink ‘U’ and downlink ‘D’ modes,

The second subset of frame configurations, e.g. frame configuration A, comprises at least one inverted frame configuration for each frame configuration of the first subset, as explained above.

For example, with reference to Table 2, a first subset of frame configurations may comprise one or more frame configurations of the frame configurations 0 to 6 highlighted in bold lines.

The second subset of frame configurations may comprise one or more frame configurations of the frame configurations A to G. Accordingly, for a frame configuration of the first subset, e.g. frame configuration 1, there may be provided an inverted complementary frame configuration A representing the best DL complement, and an inverted complementary frame configuration B representing the best US complement.

However, as mentioned above with reference to Table 1, in any of the frame configurations a ‘D’ may not be followed by a ‘U’. In other words, in this embodiment, there may be no—with respect to the frame boarders—temporally collocated pair of subframes in the respective frame configuration of the first subset and the at least one frame configuration of the second subset, of which one is associated with uplink mode while the other of the pair is associated with the downlink mode.

In each of the embodiments described herein, the aggregated TDD carriers321,322,323are selected so that a percentage of times an uplink is available to the transceiver (30) on the aggregated TDD carriers321,322,323and/or a percentage of times a downlink is available to the transceiver30on the aggregated TDD carriers321,322,323, is increased relative to each of the TDD carriers321,322,323individually.

2.2 Accelerated UL and/or DL Access Through Time-Offsets within TTI Length for Aggregated Carriers (FDD/TDD-Independent)

A further advantage of the invention shall be described with reference toFIG.13which shows, as an example, three component carriers (CCs) positioned one atop of the other. In the diagram depicted inFIG.13, a vertical axis represents a frequency while a horizontal axis represents a time.

In particular,FIG.13shows a first component carrier C1starting at a first point in time, denoted with reference numeral131. A second component carrier C2starts at a second point in time, denoted with reference numeral132. The second point in time132is later than the first point in time131. Accordingly, the first component carrier C1and the second component carrier C2are temporally shifted relative to each other.

FIG.13exemplarily also shows a third component carrier C3starting at a third point in time, denoted with reference numeral133. The third point in time133is later than the first point in time131and later than the second point in time132. Accordingly, the third component carrier C3is temporally shifted relative to the first component carrier C1and relative to the second component carrier C2.

As exemplarily depicted inFIG.13, the first component carrier C1comprises two Transmission Time Intervals TTI135aand135beach of which could, for instance, be a subframe comprising a downlink resource ‘D’, an Uplink resource ‘U’, a special resource ‘S’ or a new special resource ‘SN’. As can be seen, the first TTI135aends at a fourth point in time134, while the second TTI135bstarts at said fourth point in time134. This time interval between the first point in time131and the fourth point in time134is also referred to as the Transmission Time Interval (TTI).

In other words, each of the subcarriers C1, C2, C3may comprise an individual TTI, wherein each of these individual TTIs are shifted by a certain amount of time and thus mutually offset relative to each other. As can be seen inFIG.13, the individual but shifted TTIs may form a kind of temporal grid.

Accordingly, embodiments of the invention may provide for an apparatus configured to perform data transmission or reception via allocations of transmission or reception resources of aggregated carriers C1, C2, C3in units of transmission time intervals (TTI) into which the aggregated carriers C1, C2, C3are subdivided, wherein the aggregated carriers C1, C2, C3are temporally subdivided into the transmission time intervals in a temporal grid, respectively, wherein the aggregated carriers' grids are temporally mutually offset.

The fourth point in time134is temporally shifted relative to the first, the second and the third points in time131,132,133. In the example shown inFIG.13, the above described points in time are equally shifted or distanced from each other. That is, each point in time131,132,133,134is distanced by the same amount Δt, denoted with reference numeral136. However, according to alternative embodiments, the above described points in time may be unequally shifted or distanced from each other. That is, two or more points in time131,132,133,134may be distanced relative to each other (i.e. one relative to the subsequent one) by different amounts of time intervals Δtx.

According to the above described embodiments, a shift within the transmission time interval (TTI) length is introduced. For a number of N component carriers with equal TTI length a shift of Δc=(1/N)*TTI equidistant over time could be seen as optimal, as shown exemplarily inFIG.13. Here, component carrier C1is based on time instance C1(t) followed by C2(t+ΔT) and C3(t+2*ΔT) for constant shifts.

According to this embodiment, the aggregated carriers' grids are temporally mutually offset at an amount Δc being a non-integer multiple of the transmission time intervals TTI.

According to yet a further embodiment, the non-integer multiple Δc is smaller than one, i.e. a fraction of one.

However, as explained above, embodiments also cover the case where C1(t) would be followed by C2(t+ΔT1) and C3(t+ΔT2) and ΔT1and ΔT2would denote non-constant shifts.

An example for the basis of shifting aggregated CCs within TTI could be (but is not limited to) multiples of OFDM symbols in order to be synchronous on a symbol structure.

The benefit of this aspect of the invention is a reduction of the access cycle, i.e. the time-to-wait for the next transmission, in UL and/or DL. This aspect may well be combined with each of the above mentioned examples as described under section 2.1 to allow better continuity in UL-DL transmission on shifted carriers, e.g. improvements for UL/DL overlaps in special subframes inFIG.2, for example.

2.2.1 Externally Triggered Clock for Base Station

FIG.14shows a further embodiment of the present invention. There exist wireless systems140which need to operate on a well-defined time cycle for periodic transmission. By default these cycles may not match with the base station's (e.g. eNB)141configuration or the current (s)TTI basis.

For example, in the context of ‘Industry 4.0 (I4.0)’ the field devices1421,1422,1423,1424used in wireless industrial automation strictly need data to be present in precise moments which occur periodically on a cycle basis and is often triggered by specific external BUS systems. Usually several or all I4.0 devices1421,1422,1423,1424within one process environment140need to have the respective data present at these points in time.

The following embodiments are configured to adjust the clock of (non-anchor) component carrier of a base station141to an external entity, e.g. I4.0 device1421,1422,1423,1424.

The reconfiguring of the clock basis of a (set of) carrier(s) enables an external entity (e.g. I4.0 device1421,1422,1423,1424) or a complete system140to directly align the transmission to their application, having a maximal latency reduction on the access-cycle.

2.2.1.1 Adjust Clock of Base Station by Time Offset

Embodiments of the invention are configured to adjust the clock of a base station by a time offset through signaling on a physical channel like the PRACH in 3GPP LTE. In particular, the clock of a (non-anchor) component carrier (CC) of the eNB can be adjusted by a time offset.

For example, assuming an I4.0 factory process140, as depicted inFIG.14, may operate on a clock basis which is a multiple of the base stations141(s)TTI. However, the factory process140and the base station141may differ by a time offset. Therefore, one of the 3GPP-compliant devices in the I4.0 factory process140may be configured to adjust the clock of a (non-anchor) CC of the eNB140by a time offset.

FIG.15shows an exemplary procedure, how the time offset can be set to a (non-anchor) CC152of the eNB141according to embodiments. As can be seen, the eNB141comprises exemplarily one component carrier152and one anchor carrier151. The eNB141is configured to allocate transmission resources of the one or more carriers151,152to the I4.0 Device142for communication with the I4.0 Device142in units of transmission time intervals (TTI)1581,1582,1583into which the anchor and component carriers151,152are temporally subdivided.

The I4.0 device142is connected to the anchor carrier151and requests to adjust the clock of the (non-anchor) CC152by a time offset153. The I4.0 device142may do so by sending a request156to the eNB141.

Following, the eNB141grants the adjustment, symbolized by reference numeral157, and the I4.0 device142sets the time offset153by using the PRACH154.

A signal (e.g. random access preamble)155is transmitted on the PRACH154and the offset153to the beginning of the PRACH154denotes the time offset to adjust.

Following, said time offset153is set to the I4.0 device142and the (non-anchor) CC152, which is indicated by reference numerals153CCand153Dev. Thus, the devices1421,1422,1423,1424of the I4.0 factory process140are able to communicate on their clock basis.

As an extension, the master clock can be additionally set on the primary/anchor carrier151. However, this may currently lead to a reconfiguration/reboot of the whole system.

In other words, embodiments of the present invention may provide for a base transceiver141configured to communicate with user entity transceivers1421,1422,1423,1424via one or more carriers151,152. Said base transceiver141is configured to allocate transmission resources of the one or more carriers151,152to the user entity transceivers1421,1422,1423,1424for communication with the user entity transceivers1421,1422,1423,1424in units of transmission time intervals (TTI)1581,1582,1583into which the one or more carriers are temporally subdivided. The base transceiver141of this embodiment is further configured to temporally adjust the begin and/or end of transmission time intervals (TTI) of at least one of the one or more carriers151,152depending on one more signals155received from one of the user entity transceivers1421,1422,1423,1424.

Stated from a terminal side, i.e. from a user entity side of one or more of the above described user entities (e.g. I4.0 Devices)1421,1422,1423,1424, embodiments of the invention provide for a user entity transceiver1421,1422,1423,1424configured to communicate with a base transceiver system141via allocated transmission resources in units of transmission time intervals (TTI) into which the one or more carriers151,152are temporally subdivided. The user entity transceiver1421,1422,1423,1424according to this embodiment is configured to temporally adjust the begin and/or end of transmission time intervals (TTI) of at least one of the one or more carriers151,152to be aligned to a local clock, e.g. by depending on the local clock, send one more signals155to the base transceiver system141on the basis of which the base transceiver system141is to perform the temporal adjustment on a base transceiver system's141side.

Additionally or alternatively, the user entity transceiver1421,1422,1423,1424according to this embodiment is configured to temporally adjust the begin and/or end of transmission time intervals (TTI) of at least one of the one or more carriers151,152to be aligned to a local clock, e.g. by temporally adjusting the begin and/or end of transmission time intervals of the at least one of the one or more carriers151,152to correspond to the local clock on an user entity transceiver's1421,1422,1423,1424side.

2.2.1.2 Set Idle Time for Arbitrary System Clocks

In general, a clock of an arbitrary system is not a multiple of (s)TTI. If a time offset is applied, two systems with different clocks are still diverging.FIG.16shows this effect, where an I4.0 device142operates on a different cycle than the eNB141. Therefore, a mismatch161occurs already after the first cycle.

According to the example ofFIG.16, the eNB141operates on an internal clock cycle of 10 ms while the I4.0 Device142operates on an internal clock cycle of 9.86 ms. As can be seen, said time offset of 0.14 ms leads to a mismatch161already after the first cycle. Of course, the offset doubles to 0.28 ms (indicated by reference numeral162) already after the second cycle, and so on.

Embodiments may be described for compensating this effect. In addition to section 2.2.1.1, embodiments may provide for inserting an idle time171to the base station141, as exemplarily shown inFIG.17.

The idle time171can be signaled through a transmission on the physical channel like the PRACH154in 3GPP LTE. In particular, the transmission cycle of a (non-anchor) component carrier (CC)152of an eNB141may consist of a transmission/reception time and an idle time171. The idle time171compensates the misalignment between application cycle and size of the TTIs1581,1582,1583.

FIG.17shows an exemplary procedure, how the idle time171of a (non-anchor) CC152of the eNB141may be configured. The I4.0 device142transmits a signal (e.g. random access preamble)155on the PRACH154, signaling the idle time171of the (non-anchor) CC152.

After the signaling, the (non-anchor) CC152and the I4.0 device142may incorporate the idle time171in their transmission cycle, as symbolized by reference numerals171CCand171Dev. Thus, the devices of the I4.0 factory process are able to communicate on their arbitrary clock basis.

According to the embodiments described with reference toFIGS.15and17above, the signal (e.g. a random access preamble)155may be transmitted on the PRACH154for determining the offset153or idle time171, respectively.

According to such an embodiment, the inventive base transceiver system141is configured to perform the time adjustment (e.g. by providing an offset153or idle time171) depending on a time at which the one of the user entity transceivers142is free to send a random access signal155during a window of a physical resource channel (e.g. PRACH)154in a state of synchronization between base transceiver system141and user entity transceiver142.

From an UE side, embodiments may provide for an UE transceiver142configured to, depending on the local clock, set a time at which the user entity transceiver142sends a random access signal155during a window of a physical resource channel154in a state of synchronization between base transceiver system141and the user entity transceiver142.

Additionally or alternatively, the base transceiver system141and the UE transceiver142may both be configured to perform the adjustment (e.g. by means of the offset153or idle time171) depending on higher layer signaling.

In other words, the signal initiating the provision of an offset153or idle time171can also be a signal, or even more than one signal, different from the above described random access signal155in the PRACH154.

Accordingly, a further embodiment may provide for a base transceiver141being configured to set a clock depending on one or more signals155received from the user entity transceiver141so that the end or beginning of subsequent transmission time intervals are aligned to the clock with leaving idle times171between aligned transmission time intervals and temporally neighboring transmission time intervals.

2.2.1.3 Incorporate Timing Advance

The embodiments described above in section 2.2.1.1 and section 2.2.1.2 may not consider the time delay caused by the air transmission itself (due to the speed of light).

In communication systems like 3GPP LTE the effect is compensated by timing advance181signaled through the PRACH154, as exemplarily depicted inFIG.18.

The eNB141can consider the timing advance181of the I4.0 device142, which adjusted the eNB clock by exploiting the concepts of section 2.2.1.1 and section 2.2.1.2. Therefore, the transmission cycle of the eNB CC terminates with the I4.0 cycle, so that the transmission of all devices communicating with the eNB141are received at the end of each I4.0 cycle1821,1822,1823(cf.FIG.18).

Usually, in I4.0 all the transmission shall be terminated at the end of an I4.0 cycle1821,1822,1823. However, it could be also beneficial to align the component carrier to beginning of the I4.0 cycle1821,1822,1823.

2.2.1.4 Support of Multi-Stage Application Cycles

Further PRACH messages like in section 2.2.1.2 can support multi-stage application cycles, like alternating idle time between two values. Therefore, the entity has to signal the pattern of idle time to be applied. In addition, the PRACH message154may signal the corresponding fractional offset to the eNB141.

Furthermore, the above described embodiments have been exemplarily described by referring to the exemplary illustrations ofFIGS.14to18. According to a further embodiment, a base transceiver system may comprise more than one base station transceiver141which may be configured to communicate with one or more user entity transceivers1421,1422,1423,1424in the manner as described above.

According to such an embodiment, a base transceiver system may be provided which is configured to communicate with the user entity transceivers1421,1422,1423,1424via an aggregation of an anchor carrier152at a first base transceiver141and component carriers at a second base transceiver. The base transceiver system may further be configured to send configuration signals155for configuring the anchor and component carriers151,152at the user entity transceiver1421,1422,1423,1424, to the user entity transceiver1421,1422,1423,1424via the anchor carrier151, wherein the at least one carrier the end and/or beginning of TTIs of which is temporally adjusted is the component carrier152.

2.2.2 Time-Offsets Only for a Set of Physical Layer Channel on Aggregated Carriers

The general scheme described in section 2.2.1 can also be used for special signaling intervals e.g. PDCCH signaling or broadcast control information, as exemplarily depicted inFIGS.19A to19C.

By selecting time-shifted control signaling relevant physical layer channels of carriers in common CA mode, a UE has accelerated access to the needed signaling information while maintaining backward compatibility. Also, the random access procedure as done in physical random access channel (PRACH) in UL can be accelerated.

An example is shown inFIG.19Bfor the shifted PRACH on 3 carriers C1, C2, C3. Here, the shift191is done in a constant way such that there are three PRACH access options within one TTI for a UE that uses three carriers C1, C2, C3.

Alternatively, the signaling can be reduced while keeping the same access time.

Accordingly, embodiments provide for an apparatus configured to perform data transmission or reception via allocations of transmission resources of aggregated carriers C1, C2, C3, wherein at least one of physical layer channels of the aggregated carriers C1, C2, C3, radio frame bases of physical broadcast channels of the aggregated carriers C1, C2, C3, and physical random access channels (e.g. PRACH) of the aggregated carriers C1, C2, C3are temporally mutually offset.

For example inFIG.19B, the channels of carriers C1, C2and C3are temporally shifted by time shift191. As depicted inFIG.19C, only parts of the channels may be shifted by time shift192, wherein only those shifted parts may be available which may therefore also be referred to as a reduced signaling.

Independent of whether physical channels, as depicted inFIGS.19A to19C, or communication resources like ‘U’, ‘D’, ‘S’, ‘SN’, as explained above with reference to the other figures, may be transmitted, embodiments of the invention provide for inbound data being sent at the earliest point in time by using the subsequent TTI or subframe of at least one of available further aggregated carriers.

In other words, embodiments provide for an apparatus comprising at least one base station and being configured to select for inbound data ready to be transmitted at a predetermined time instant, one of the aggregated carriers (321,322,323) such that the one of the aggregated carriers (321,322,323) has a predetermined transmission time interval which starts earliest on or after the predetermined time instant, and transmit the inbound data in the predetermined transmission time interval.

From an UE point of view, embodiments provide for a mobile terminal being configured to select for inbound data ready to be transmitted at a predetermined time instant, one of the aggregated carriers (321,322,323) such that the one of the aggregated carriers (321,322,323) has a predetermined transmission time interval which starts earliest on or after the predetermined time instant, and request at the base station system (30) a transmission of the inbound data in the predetermined transmission time interval.

2.2.3 Further Embodiments

FIG.20shows a further embodiment for providing a time offset153or idle time171, respectively.

According to this embodiment, the eNB141may be configured to send a first interrogation signal201. The user equipment device142may be configured to respond to said first interrogation signal201by sending a first response signal202to the eNB141. The time span between receiving the first interrogation signal201and sending the first response signal202is denoted with Δt1inFIG.20.

The eNB141may further be configured to send a second interrogation signal203. The user equipment device142may be configured to respond to said second interrogation signal203by sending a second response signal204to the eNB141. The time span between receiving the second interrogation signal203and sending the second response signal204is denoted with Δt2inFIG.20.

As can be seen, the time span Δt2is larger than the time span Δt1. In other words, the response time Δt2of the second response signal204for responding to the second interrogation signal203is delayed when compared to the response time Δt1of the first response signal202for responding to the first interrogation signal201. This difference between Δt1and Δt2may depend on the desired clock setting and may represent a communication delay. It may also be referred to as an offset153or idle time171, respectively.

Additionally or alternatively, the base transceiver system eNB141may send an information regarding the communication delay to the user equipment device142. The user equipment device142may receive said information subsequent to responding to the first interrogation signal201, i.e. subsequent to sending the first response signal202.

The user equipment device142may determine a reference sending time on the basis of the temporal grid and the communication delay. Following, the user equipment device142may send the second response signal204to the eNB141delayed relative to the reference sending time depending on the local clock.

Furthermore, the end and/or beginning of the TTIs may then be adjusted depending on said local clock setting on the user equipment side142.

In other words, embodiments provide for an user entity transceiver141configured to respond to a first interrogation signal201sent by the base transceiver system141by sending a first response signal202to the base transceiver system141. The user entity transceiver141of this embodiment may further be configured to perform the temporal adjustment by responding to a second interrogation signal203sent by the base transceiver system141by sending a second response signal204to the base transceiver system141in a manner delayed relative to the responding to the first interrogation signal201by a time delay depending on the wanted clock setting.

Additionally or alternatively, The user entity transceiver141of this embodiment may be configured to receive an information on a communication delay from the base transceiver system141subsequent to the responding to the first interrogation signal201, determining a reference sending time on the basis of the temporal grid and the communication delay and sending a second response signal204to the base transceiver system141delayed relative to the reference sending time depending on the local clock.

In either way, the user entity transceiver141of this embodiment may be configured to adjust the end and/or beginning of TTIs depending on the local clock setting on the UE transceiver's side142.

From a eNB side141, embodiments provide for a base transceiver system141configured to perform the temporal adjustment by determining a time past Δt1between a first interrogation signal201sent by the base transceiver system141and a first response signal202sent by the user entity transceiver142responsive to the first interrogation signal201.

The base transceiver system141is further configured to perform the temporal adjustment on the basis of a prolongation (ΔT=Δt2−Δt1) of a time past Δt2between a second interrogation signal203sent by the base transceiver141and a second response signal204sent by the user entity transceiver142responsive to the second interrogation signal203, relative to the first time delay.

Additionally or alternatively, the base transceiver system141is configured to perform the temporal adjustment on the basis of a time past Δt2between the second response signal204sent by the user entity transceiver142subsequent to the first response signal202, upon the base transceiver system141having informed the user entity transceiver142on the first time delay153,171on the one hand and a reference arrival time of the second response signal204determined by the base transceiver system141on the basis of the temporal grid.

2.3 Extended Dual TDD Operation Using Multiple (e.g. Two or More) Antennas with Carrier Aggregation and Inverted Switching Points

FIG.21shows some embodiments for dual TDD operation using two or more antennas.

The top diagram211shows a permanent single stream in Uplink and Downlink operation, wherein antenna1is operated in transmit mode and antenna2is operated in receive mode.

The diagram212in the middle shows a permanent dual stream Uplink and Downlink operation switching between two transmit antennas on CC-A and two antennas on CC-B.

The diagram213at the bottom shows a permanent dual stream Uplink and Downlink operation using one transmit antenna on CC-A and another transmit antenna on CC-B.

InFIG.21, each of the two or more antennas as mentioned above may be switched such that one antenna is in receive mode on CC-A while the other is in transmit mode on CC-B. In case of four Antennas at the base station141or terminal (e.g. UE142) this will allow for a continuous dual stream downlink and uplink transmission at the same time keeping UL and DL on different CC.

As an example: if CC-A was 1.8 GHz and CC-B was 2.6 GHz then an OOB emission mask should decouple the UL and DL streams even without explicit filters due to the significant distance in frequency. In case of full-duplex (self-interference cancellation mechanism) capabilities the enhanced self-interference cancelation can be applied over a quasi constant channel between the “de-facto” permanently as transmitter operated antennas and the permanently as receiver operated antennas.

Additionally or alternatively the TDD switching may not be performed between transceiver and antenna but instead in base band between the output of the CCs. In this way real TDD switches can be either omitted or can have switching slope support of standard TDD frame structures.

At one end of the transmission link, either UE side142or base station side141, the CCs might be allocated to different/distributed antennas or sites (access points) in order to provide sufficient decoupling between Tx and Rx operating on CCs close to each other.

Additionally or alternatively, two sufficiently decoupled antennas may be used within one device with UL on CC-A and DL on CC-B in “quasi” half-duplex mode allowing for continuous single stream UL and DL.

Further additionally or alternatively, in case of adjacent CCs used for UL and DL operation at the same time, the scheduler may support improved UL-DL interference decoupling by appropriate PRB allocation, similar to section 2.1.3 described above.

According to such dual stream, or dual TDD, operation embodiments of the invention provide for a transceiver being a base station system141, wherein said base station system141comprises one or more base stations with a plurality of antenna ports and configured to distribute uplink times and downlink times of the aggregated TDD carriers onto the plurality of antennas such that exclusively uplink times are attributed to a first subset of the plurality of antennas and exclusively downlink times are attributed to a second subset of the plurality of antennas, the first and second subset being disjoint.

Further embodiments may provide for a transceiver being a mobile terminal142configured for communicating with a third party device, wherein the third party device is a base station system comprising one or more base stations with a plurality of antenna ports. The transceiver142of this embodiment may be configured to distribute uplink times and downlink times of the aggregated TDD carriers onto the plurality of antennas such that exclusively uplink times are attributed to a first subset of the plurality of antennas and exclusively downlink times are attributed to a second subset of the plurality of antennas, the first and second subset being disjoint.

The above mentioned examples and embodiments have been exemplarily described with reference to existing networks of the fourth generation, the so-called 4G or LTE and LTE-Advanced and 4.5G LTE-Advanced Pro networks. Of course, all of the concepts described herein may also be used in mobile networks of the fifth generation, the so-called 5G or New Radio (NR) networks.

The 5G NR networks may enable much shorter latencies than currently existing 4G networks. For instance, as explained with reference toFIG.1, LTE may support a fixed TTI of 1 ms. An 5G NR network may use shorter TTIs, i.e. the so-called shortened TTIs (sTTI) which have been explained above, inter alia with reference toFIG.4. For example, it may be possible to provide a transmission latency comparable to six shortened TTI, as exemplarily shown on the right hand side ofFIG.4. A number of six shortened TTI is only mentioned as an example here, whereas the 3GPP strives to provide up to eight shortened TTI (sTTI, 1.14 ms) with 143 μs sTTi and more. Accordingly, the 5G NR networks may exploit the sTTI as described herein.

As it was explained further above with reference toFIG.7, a LTE-compatible standard 1 ms subframe may comprise two slots, wherein each slot may comprise seven symbols. This subframe structure is again shown inFIG.22denoted with reference numeral220A. It shows a subframe220A according to 4G LTE or LTE-Advanced, wherein the subframe220A comprises a slot221, and wherein each slot221comprises seven symbols222.

Other services or network standards, in particular NR, may be configured to use a shorter TTI, for instance a 500 μs TTI instead of the aforementioned standard LTE-compatible 1 ms TTI or subframe220A, respectively. Such an example is shown inFIG.22, denoted with reference numeral220B. In comparison to the standard LTE-compatible 1 ms subframe220A, the TTI of this example is shortened by exactly the half, i.e. shortened to 500 μs instead of 1 ms. However, for this purpose the so-called subcarrier spacing (SCS) has to be doubled from 15 kHz for the standard LTE-compatible 1 ms subframe220A to 30 kHz for this shortened 500 μs subframe220B.

However, 5G NR networks may exploit further possibilities for providing shorter TTIs, namely the above mentioned sTTI, for example by reducing the length of the slots. Accordingly, subframes used in 5G NR networks may use so-called mini-slots. An exemplary subframe using a mini-slot is shown inFIG.22, denoted with reference numeral220C.

This 5G NR subframe220C uses a mini-slot223which comprises only two symbols (e.g. OFDM-symbols)224instead of the above mentioned seven symbols222comprised by the LTE-compatible 1 ms standard subframe220A. These two symbols224of the 5G NR subframe220C may have a sTTI of temporal length T≈142 μs.

Of course, the depicted mini-slot223was only shown here as an example. Generally, mini-slots223may have different lengths depending on the used carrier frequencies. Mini-slots may have a length of exactly one symbol (e.g. one OFDM symbol), e.g. typically used for frequencies above 6 GHz, or mini-slots may have a length of two up to slot-length-1 symbols, e.g. if the carrier frequency is below 6 GHz. This may depend on the URLLC requirements (URLLC: Ultra Reliable Low Latency Communications), where at least a mini-slot length of two symbols shall be supported for frequencies below 6 GHz.

In addition, this concept may be combinable with a subcarrier spacing (SCS) depending on the numerology. For 5G NR, the SCS may vary, depending on the used carrier frequency, according to the following formula:
f(n)=15 kHz·2n; wherenis a non-negative integer
An example for a sTTI combined with a variable SCS is shown inFIG.22, denoted with reference numeral220D. It shows a further 5G NR subframe220D with eight symbols. Accordingly, the SCS may have to be increased to 60 kHz.

Furthermore,FIG.23shows several examples in which frequency bands which SCS may be used (k=kHz).

Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be executed by (or using) a hardware apparatus, like for example, a microprocessor, a programmable computer or an electronic circuit. In some embodiments, one or more of the most important method steps may be executed by such an apparatus.

Depending on certain implementation requirements, embodiments of the invention can be implemented in hardware or in software or at least partially in hardware or at least partially in software. The implementation can be performed using a digital storage medium, for example a floppy disk, a DVD, a Blu-Ray, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, having electronically readable control signals stored thereon, which cooperate (or are capable of cooperating) with a programmable computer system such that the respective method is performed. Therefore, the digital storage medium may be computer readable.

Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.

Generally, embodiments of the present invention can be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer. The program code may for example be stored on a machine readable carrier.

Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier.

In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

A further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein. The data carrier, the digital storage medium or the recorded medium are typically tangible and/or non-transitory.

A further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein. The data stream or the sequence of signals may for example be configured to be transferred via a data communication connection, for example via the Internet.

A further embodiment comprises a processing means, for example a computer, or a programmable logic device, configured to or adapted to perform one of the methods described herein.

A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

A further embodiment according to the invention comprises an apparatus or a system configured to transfer (for example, electronically or optically) a computer program for performing one of the methods described herein to a receiver. The receiver may, for example, be a computer, a mobile device, a memory device or the like. The apparatus or system may, for example, comprise a file server for transferring the computer program to the receiver.

In some embodiments, a programmable logic device (for example a field programmable gate array) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor in order to perform one of the methods described herein. Generally, the methods are performed by any hardware apparatus.

The apparatus described herein may be implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

The methods described herein may be performed using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

While this invention has been described in terms of several advantageous embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.

LIST OF ACRONYMS AND SYMBOLS

BSBase Station*eNBEvolved Node B (3GPP base station)LTELong-Term EvolutionUEUser Equipment (User Terminal)DwPTSDownlink Pilot Time SlotUpPTSUplink Pilot Time SlotGPGuard PeriodCACarrier AggregationCCComponent CarrierTDDTime Division DuplexFDDFrequency Division DuplexMIMOMultiple Input Multiple OutputOFDMOrthogonal Frequency Division DuplexingCQIChannel Quality InformationDCIDownlink Control InformationULUplinkDLDownlink(s)TTI(short) Transmission Time IntervalPSSPrimary Synchronization SignalSSSSecondary Synchronization SignalPRBPhysical Resource Block(P)RACH(Physical) Random Access ChannelPDCCHPhysical Downlink Control Channel*Note,the term eNB is a general term for a base station (BS) of the communication network (used in the LTE context), for 5 G (New Radio) communication networks, the term gNB is used. All three terms BS, eNB and gNB may be used as synonym in this description.

REFERENCES

[1]3GPP TS36.211 V13.1.0 (2016 Mar.), “E-UTRA; Physical channelsand modulation”, p. 13 f.[2]3GPP TR36.881 V0.6.0 (2016 Feb.), “Study on latency reductiontechniques for LTE”.[3]C. Johnson, “Long Term Evolution in Bullets”, 2nd edition, 2012,p. 289 ff.[4]http://www.sharetechnote.com/html/LTE_TDD_Overview.html[5]http://niviuk.free.fr/lte_resource_grid.html