WO2015019562A1

WO2015019562A1 - A method, an access node, a user equipment and a wireless communications network

Info

Publication number: WO2015019562A1
Application number: PCT/JP2014/003859
Authority: WO
Inventors: Phong Nguyen; Kevin Lin
Original assignee: Nec Corporation
Priority date: 2013-08-08
Filing date: 2014-07-23
Publication date: 2015-02-12

Abstract

In a wireless communications network (100) including a first access node (110) and a second access node (120), a method implemented in the second access node (120) includes: transmitting new carrier type (NCT) radio frames including, a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE (160) capable of carrier aggregation (101); and a second radio frame inoperable to support the first UE and operable to support the second UE, in which the first access node (110) transmits legacy radio frames.

Description

A METHOD, AN ACCESS NODE, A USER EQUIPMENT AND A WIRELESS COMMUNICATIONS NETWORK

The present invention relates to a method, an access node, a user equipment and a wireless communications network.

The following abbreviations are used herein:

For mobile wireless communication systems, the existing design of LTE radio frame and subframe structures in Rel. 8, 9, 10 and 11 can support both standalone and carrier aggregation operations in homogeneous and heterogeneous networks. The current type 1 and type 2 radio frame structures inherited from LTE Rel. 8 (hereafter referred to as the legacy LTE carrier or legacy carrier type) are depicted in Figs. 1A and 1B. For both types of frame structure, one radio frame is defined as being 10ms long and consisting of 10 subframes of equal (1ms) length. Each subframe is further divided into two slots each of 0.5ms duration.

For frame structure type 1 (Fig. 1A) which is applicable for FDD operation, all subframes can be used for downlink transmission and are hereafter denoted as downlink subframes. For frame structure type 2 (Fig. 1B) which is applicable for TDD operation, three types of subframes are specified, namely downlink subframes, uplink subframes and special subframes. In Fig. 1B, subframes #1 and #6 includes DwPTS (Pilot Time Slot), GP (Guard Period) and UpPTS. The supported uplink-downlink configurations for LTE are listed in Table 1 below.

Table 1: Uplink-downlink configurations for LTE

The LTE radio frame structure for type 1 is depicted in more detail in Fig. 2. As shown in Fig. 2, in legacy subframes #0 and #5, a base-station always transmits synchronisation signals for cell detection and carrier frequency/timing reference, regardless of system operation type and deployment scenario. Similarly, the broadcast PBCH signal carrying cell information encoded in MasterInformationBlock (MIB) is also always transmitted in subframe #0.

Furthermore, when the other subframes (

i.e. subframes #

1, 2, 3, 4, 6, 7, 8 & 9) depicted in Fig. 3 are included, full CRS {Cell-specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} for demodulation and RRM/RLM/CSI measurement, and time domain control region (comprising PCFICH, PDCCH and PHICH signals and occupying 1 or 2 or 3 or 4 OFDM symbols) for sending downlink control signalling and Hybrid-ARQ acknowledgements, are always transmitted over the entire carrier bandwidth in all legacy subframes.

In Rel. 11, to accommodate possible high numbers of user equipments (UEs) within a cell, a frequency domain control region, which is in addition to the always transmitted time domain control region, can be configured in any or all downlink subframes by the base-station for servicing Rel. 11 and later UEs (i.e. UEs compatible with Rel. 11 and beyond).

According to Rel. 10 and 11 carrier aggregation, the above described frame and subframe structures of the legacy LTE carrier should be deployed from cell base-stations as the primary component carrier (PCell) and the secondary component carrier (SCell). However, the broadcast PBCH signal should still be transmitted in the SCell, although system information of the SCell should be always provided to UEs by dedicated RRC-signalling.

With a view to achieving higher end-user data rates, improve support of HetNet deployments and reduce network energy consumption, a new work item to specify a New Carrier Type (NCT) for Release 12 has been introduced in 3GPP. It has been identified that the aims just mentioned may be achieved by enhancing transmission of data and control on the NCT, minimising legacy control signalling and cell-specific reference signalling, and thus reducing the interference and overhead level at low-to-medium loads, allowing for higher end-user throughput and improved system spectral efficiency. These benefits may be particularly appealing at the cell edge in homogeneous deployments, in a cell range expansion zone of heterogeneous deployments and for enhanced local area access in the deployment scenario of low-power nodes (small cells) with or without coverage of an existing macro-node layer.

For the design of the NCT, it has been determined that one reference signal port consisting of the Rel. 8 CRS port 0 REs and Rel. 8 sequence within 1 subframe and 5ms periodicity can be transmitted. It has also been determined that this reduced-CRS (R-CRS) port is not to be used for demodulation. These determinations consequently have an impact on supporting legacy UEs on the NCT if CRS cannot be used for decoding essential system information on broadcast channel and demodulating legacy control channels. Furthermore, there has not been a clear determination about the subframes in which the R-CRS can be transmitted and its transmission bandwidth. Therefore, it is necessary to re-design the broadcast PBCH signal (i.e. to design a new ePBCH), to re-design the common search space (CSS) for frequency domain control signalling (i.e. to design a new CSS on EPDCCH), and to re-design Hybrid-ARQ acknowledgement signalling (i.e. to design a new EPHICH) for the NCT carrier.

In view of the foregoing, it would appear to be desirable to provide a new carrier type (NCT) radio frame design that may provide some degree of backward compatibility to provide limited connectivity to legacy UEs, and which may also adopt non-backward compatible enhancements to further improve user experience/throughput, energy conservation and allow new heterogeneous network (HetNet) deployment.

It is to be clearly understood that mere reference herein to previous or existing apparatus, products, systems, methods, practices, publications or other information, or to any problems or issues, does not constitute an acknowledgement or admission that any of those things individually or in any combination formed part of the common general knowledge of those skilled in the field, or that they are admissible related art.

In one form at least, in a wireless communications network including a first access node and a second access node, the present invention provides a method implemented in the second access node. The method includes:
transmitting new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
in which the first access node transmits legacy radio frames.

In a first embodiment/deployment scenario (or group of embodiments/deployment scenarios), the first access node may provide a primary component carrier (PCell), and the second access node may provide a secondary component carrier (SCell) as an aggregated carrier.
Where this is the case, the legacy radio frames and the NCT radio frames may be one of the followings: frequency division duplex (FDD) and time division duplex (TDD) respectively, TDD and FDD respectively, TDD and TDD respectively, or FDD and FDD respectively.

In a second embodiment/deployment scenario (or group of embodiments/deployment scenarios), the first access node may provide wireless connectivity for a UE to establish control plane communication through the first access node before the UE switches connectivity to the second access node whereupon the UE establishes data plane communication and continues to maintain the said control plane communication through the second access node. In this case, the legacy radio frames and the NCT radio frames may be one of the followings: FDD and FDD respectively, or TDD and TDD respectively.

In a third embodiment/deployment scenario (or group of embodiments/deployment scenarios), the first access node may provide wireless connectivity for a UE to establish a first connectivity for control plane communication through the first access node, and the first access node may assist the UE to establish a second connectivity for data plane communication through the second access node, whereupon the UE conducts data plane communication through the second access node but conducts control plane communication through the first access node. In this scenario, the legacy radio frames and the NCT radio frames may be one of the followings: FDD and TDD respectively, FDD and FDD respectively, or TDD and TDD respectively.

In a fourth embodiment/deployment scenario (or group of embodiments/deployment scenarios), a UE may detect the second access node during cell search without or with some assistance from the first access node and conduct data communication through the second access node. In this situation, the NCT radio frames may be FDD or TDD.

In all of the embodiments/deployment scenarios mentioned above, the first radio frame may include one or more legacy type subframes of which are time-multiplexed with new carrier type subframes. In the first radio frame, the new carrier type subframes may include zero, one, or more frequency domain control regions which are frequency-multiplexed with one or more frequency domain data regions. The second radio frame may include time-multiplexed new carrier type subframes.

In another form at least, in a wireless communications network including a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation, the present invention provides a method implemented in the second UE. The method includes:
receiving, from a second access node, new carrier type (NCT) radio frames including:
a first radio frame operable to support the first user equipment (UE) and the second UE; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
in which a first access node transmits legacy radio frames.

In another form at least, the present invention provides a method implemented in a wireless communications network including a first access node and a second access node. The method includes:
transmitting, from the second access node, new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
transmitting, from the first access node, legacy radio frames.

In another form at least, the present invention provides an access node used in a wireless communications network. The access node includes:
a transmitter to transmit new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
in which another access node in the wireless communications network transmits legacy radio frames.

In another form at least, the present invention provides a user equipment (UE) capable of carrier aggregation and used in a wireless communications network including a first access node and a second access node. The UE includes:
a receiver to receive, from the second access node, new carrier type (NCT) radio frames including:
a first radio frame operable to support the user equipment (UE) and another UE incapable of carrier aggregation; and
a second radio frame inoperable to support the UE and operable to support said another UE,
in which the first access node transmits legacy radio frames.

In the other form at least, the present invention provides a wireless communications network. The wireless communications network includes:
a first access node transmitting legacy radio frames;
a second access node transmitting new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE.

According to the present invention, it is possible to achieve higher end-user data rates, improve support for HetNet deployment, and/or reduce network energy consumption.

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:
Fig. 1A illustrates the current type 1 radio frame structures inherited from LTE Rel. 8 (this is referred to herein as the legacy LTE carrier or legacy carrier type); Fig. 1B illustrates the current type 2 radio frame structures inherited from LTE Rel. 8; Fig. 2 illustrates the legacy LTE carrier radio frame structure (type 1) in more detail; Fig. 3 illustrates the legacy subframe structure for

subframes #

1, 2, 3, 4, 6, 7, 8, and 9; Fig. 4 is a schematic illustration of advanced wireless communications system in which a number of heterogeneous network (HetNet) deployment scenarios are represented; Fig. 5A illustrates a frame and subframe structure of a backward compatible NCT operating as an aggregated carrier; Fig. 5B illustrates the subframe structure shown in Fig. 5A in more detail; Fig. 6A illustrates a frame and subframe structure of a non-backward compatible NCT operating as an aggregated carrier; Fig. 6B illustrates the subframe structure shown in Fig. 6A in more detail; Fig. 7A illustrates a frame and subframe structure of a backward compatible NCT operating as a macro-assisted carrier or a stand-alone NCT; Fig. 7B illustrates the subframe structure shown in Fig. 7A in more detail; Fig.8A illustrates a frame and subframe structure of a non-backward compatible NCT operating as a macro-assisted carrier or a stand-alone NCT and Fig.8B illustrates the subframe structure shown in Fig. 8A in detail in more detail.

The explanations below may assist further in understanding the invention and certain embodiments of it.

Generally speaking, the invention involves a method which may be implemented in one or more base-stations used in a heterogeneous network. The method may help to achieve higher end-user data rates, improve support for HetNet deployment, and/or reduce network energy consumption. The method in different embodiments or deployment scenarios may involve transmitting the NCT (new carrier type) from a small cell base-station as an aggregated carrier with carrier aggregation deployment (first embodiment above), as a macro assisted carrier with single connectivity deployment (second embodiment above), as a macro assisted carrier with dual connectivity deployment (third embodiment above) and/or as a standalone carrier (fourth embodiment above).

In the case of the first embodiment, a macro-base-station and a pico-base-station within the macro-base-station coverage may form a heterogeneous network for carrier aggregation. A UE may initially establish RRC-connection with the macro-base-station (first base-station or first access node) using the legacy carrier serviced by the macro-base-station. Via dedicated RRC-signalling, the UE may be configured to add and establish a SCell (secondary carrier component) that is serviced by the pico-base-station (second base-station or second access node). In order to support legacy UEs and advanced UEs, the pico-base-station may be configured by the mobile network to transmit first NCT radio frames each of which comprises subframes of legacy type time multiplexed with new carrier type subframes. For a FDD system, the first NCT radio frame may comprise at least two legacy DL subframes. These may be subframes #0 and subframe #5 and the remaining eight NCT

subframes being #

1, 2, 3, 4, 6, 7, 8 and 9. By observing traffic to and/or from a legacy UE and/or an advanced UE, the mobile network may further configure the pico-base-station to transmit a legacy type DL subframe on one or more subframes of a radio frame that belongs to subframe set {1, 2, 3, 4, 6, 7, 8, 9}. On subframes #0 and #5, the pico-base-station may be configured to transmit CRS and optionally also a synchronisation signal. For the purpose of reducing energy consumption as well as increasing end-user data rate, the pico-base-station may be configured to optionally also silent a broadcast signal to allocate the reserved RE(s) for transmitting data. On any DL subframes of legacy type in the first NCT radio frame, the pico-base-station may be configured to optionally transmit a time domain control signal and/or a frequency domain control signal, hence further allocating more RE(s) in a subframe for data. On any subframes of new carrier type in the first NCT radio frame, the pico-base-station may be configured to transmit a frequency domain control signal servicing Rel. 11 and advanced UEs. By observing traffic to and/or from legacy UEs and advanced UEs, the mobile network may reserve a pico-base-station for servicing advanced UE(s) only. In this case, the mobile network may configure the pico-base-station to transmit a second NCT radio frame comprising time multiplexed subframes of new carrier type. On each subframes of new carrier type in the second NCT radio frame, the pico-base-station may be configured to transmit zero, one or more frequency domain control region(s) which are frequency multiplexed with frequency domain data region(s). For a configured transmitted frequency domain control region, the pico-base-station may be configured to further reserve RE(s) within the said control region for the mapping of EPHICH carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH. An advanced UE may be informed of the EPHICH-config via dedicated RRC-signalling on the first carrier component. For a FDD system, on DL subframe #0 and #5 of the second NCT radio frame, the pico-base-station may (optionally) be configured to transmit a synchronisation signal. And on DL subframe #0 of the second NCT radio frame, the pico-base-station may be configured to a silent broadcast signal to reserve the physical channel for transmitting data. On any pair of DL subframes in the second NCT radio frame that are 5ms apart, such as subframes #0 and #5, the pico-base-station may be configured to transmit configurable R-CRS (Reduced cell specific reference signal i.e. port 0 CRS) within a network configurable bandwidth, preferably 5 MHz or Full system bandwidth. The transmission bandwidth for R-CRS should be the same as the carrier or system bandwidth, when the carrier bandwidth indicated in the system information is 5 MHz or less. An advanced UE in a RRC-connected state may be informed of the R-CRS bandwidth via dedicated RRC-signalling on the primary component carrier. An advanced UE may be further informed, via dedicated RRC-signalling on the primary component carrier, of the paired subframes within a second NCT radio frame that are allocated for R-CRS mapping. Optionally, paired subframes within a second NCT radio frame that are allocated for R-CRS mapping may be self-decodable using physical Cell-ID.

In the case of a deployment such as in the second embodiment, the macro-base-station and the pico-base-station within the macro-base-station coverage may again form a heterogeneous network. A UE may initially establish RRC-connection with the macro-base-station using the legacy carrier serviced by the macro-base-station. Via dedicated RRC-signalling, the UE may be configured to switch or handover to the pico-base-station. In order to support legacy UEs and advanced UEs, the pico-base-station may be configured by the mobile network to transmit first NCT radio frames (i.e. first NCT radio frames of the kind discussed above). In order to support only advanced UEs, the pico-base-station may be configured by the mobile network to transmit second NCT radio frames (which are, again, of the kind discussed above). However, unlike in the first embodiment discussed above, in the presently discussed second embodiment, on subframes of new carrier type in the first NCT radio frame and/or the second NCT radio frame, the pico-base-station may in addition be configured to transmit EPDCCH for common search space (CSS) in one or more frequency domain control regions. Prior to switching or handover from the macro-base-station to the pico-base-station, an advanced UE may be informed via dedicated RRC-signalling of the location of the frequency domain control region(s) having the mapping of EPDCCH for CSS.

In the case of a deployment such as in the third embodiment, the macro-base-station and the pico-base-station within the macro-base-station coverage may again form a heterogeneous network. A UE may initially establish RRC-connection with the macro-base-station using the legacy carrier serviced by the macro-base-station. Via dedicated RRC-signalling, a UE may be configured to establish a second connectivity with the pico base-station for user plane data transmission and reception while still maintaining the first connectivity with the macro-base-station for control plane data (i.e. RRC signalling) transmission and reception. In order to support legacy UEs and advanced UEs, the pico-base-station may again be configured by the mobile network to transmit first NCT radio frames of the kind discussed above, and in order to support only advanced UEs the pico-base-station may be configured by the mobile network to transmit second NCT radio frames which are, again, of the kind discussed above. However, unlike the case of the second embodiment discussed above, in the presently discussed third embodiment, a legacy UE or advanced UE may still maintain the connectivity with the macro-base-station for dedicated RRC-signalling in order to support mobility management as well as the user plane data transmission and reception on the second connectivity with the pico-base-station.

In situations such as in the fourth embodiment, where the pico base-station may not be within the macro base-station coverage, the NCT radio frames transmitted by the pico base-station may operate as a standalone carrier to provide limited wireless connectivity to legacy UE(s) or full wireless connectivity to advanced UE(s) within the pico base-station coverage. In contrast to the other embodiments/deployment scenarios discussed above, in this scenario a UE may initially establish RRC-connection with the pico-base-station (second base-station) which transmits NCT radio frames. In order to support legacy UEs and advanced UEs, the pico-base-station may again be configured by the mobile network to transmit first NCT radio frames which include subframes of legacy type that are time multiplexed with new carrier type subframes. For a FDD system, the NCT radio frame may comprise at least four legacy type DL subframes. These may be

subframes #

0, 4, 5 and 9 and the remaining six NCT

subframes being #

1, 2, 3, 6, 7 and 8. By observing traffic to and from legacy UEs and advanced UEs, the mobile network may further configure the pico-base-station to transmit a legacy DL subframe on one or more subframes that belong to the subframe set {1, 2, 3, 6, 7, 8}. On subframes #0 and #5, the pico-base-station may be configured to transmit CRS, synchronisation signal, broadcast signal and time domain control signal. On other subframes of legacy type, the pico-base-station may be configured to transmit CRS and time domain control signal. In order to increase control signalling capacity supporting Rel. 11 and advanced UEs on subframes of legacy type, the pico-base-station may be configured to further transmit frequency domain signal. On any subframes of new carrier type in the first NCT radio frame, the pico-base-station may be configured to transmit a frequency domain control signal servicing Rel. 11 and advanced UE. By observing traffic to and/or from legacy UE(s) and advanced UE(s), the mobile network may reserve a pico-base-station for servicing advanced UE(s) only. In this case, the mobile network may configure the pico-base-station to transmit second NCT radio frames comprising time multiplexed subframes of new carrier type. On each subframes of new carrier type in the second NCT radio frame, the pico-base-station may be configured to transmit one or more frequency domain control region(s) which are frequency multiplexed with frequency domain data region(s). For a control region consisting of EPDCCH for CSS (Common search space) or a control region consisting EPDCCH for CSS and USS (UE specific search space), the pico-base-station may transmit this control region on PRB pair(s) that can be blindly detected by an advanced UE. Since a legacy UE may be barred from accessing the pico-base-station in this case. On subframe #0, the pico-cell cell broadcast signal (MIB) transmitted on ePBCH may be mapped on predetermined PRB pairs within central six PRBs, that are known only to advanced UE(s). In this case, a legacy UE will not be able to access cell information of the pico-base-station. MIB broadcasted on ePBCH may preferably have the same structure as in previously proposed 3GPP LTE. Additionally, the broadcast MIB may further comprise information on R-CRS bandwidth (Reduced cell specific reference signal i.e. port 0 CRS) preferably using two spare bits to indicate reserve (00), 5 MHz for R-CRS (01), Full system bandwidth for R-CRS (10) or zero PRBs or no transmission (11). An advanced UE may use the detected Cell-ID to derive paired subframes within a radio frame that the said pico-base-station configured to transmit R-CRS (i.e. self-decodable using Cell-ID and 'MOD' function with predefined variable such as 2 or 5).

Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

Fig. 4 illustrates an advanced wireless communication system (network) 100 in which a number of heterogeneous network deployment scenarios are represented which utilise a proposed New Carrier Type (NCT). As just stated, the advanced wireless communication system 100 is a heterogeneous network (HetNet) comprising several macro access nodes 110 representing macro-base-stations, a number of small cell access nodes (including the ones denoted 120, 130, 140 and 150) representing pico-base-stations that can be configured to transmit the disclosed NCT signal supporting legacy UEs (such as Rel. 8, 9, 10 or 11 UEs) and/or advanced UEs, and a plurality of advanced user equipment (UEs) 160 that may be capable of processing the proposed NCT signal transmitted from the small cell access nodes. Macro-base-stations 110 serve the macro-cells over a first carrier frequency F1. Pico-base-

stations

120, 130, 140 or 150 (and the other small cell access nodes) serve the small-cells over a second carrier frequency F2. The first carrier frequency F1 and the second carrier frequency F2 could be same or different.

I. Aggregated carrier

The first illustrated deployment scenario (carrier aggregation) is denoted 101 in Fig. 4. According to this first deployment scenario, a UE (i.e. a Rel. 10 or 11 UE or an advanced UE) can detect and camp on a macro-cell that is serviced by a macro-base-station 110. The said UE first establishes RRC connection with the mobile network through the macro-base-station 110. Then, via dedicated RRC signalling through the macro-base-station 110, the said UE is configured to perform small cell measurement and to add a second carrier component serviced by the pico-base-station 120 as an aggregated carrier for additional data reception and transmission in addition to the primary carrier component that is serviced by the macro-base-station 110. The primary carrier component serviced by the macro-base-station 110 should be LTE FDD whereas the secondary carrier component serviced by the pico-base-station 120 may be either LTE FDD or LTE TDD.

II. Macro assisted carrier with single connectivity ("switching over")

The second illustrated deployment scenario is denoted 102 in Fig. 4. According to this second deployment scenario, a UE (i.e. a Rel. 8, 9, 10, 11 UE or advanced UE) can detect and camp on a macro-cell that is serviced by a macro-base-station 110. The said UE first establishes RRC connection with the mobile network through macro-base-station 110. Then, via dedicated RRC signalling through the macro-base-station 110, the said UE is configured to perform small cell measurement serviced by the pico-base-station 130 and to report the measurement result through macro-base-station 110 connectivity. Once all conditions for signal reception and transmission with the pico-base-station 130 are satisfied, the said UE, via dedicated RRC signalling through the macro-base-station 110, is configured to switch or handover to performing signal reception and transmission through the pico-base-station 130 while maintaining the same RRC connection with the mobile network as before but instead through pico-base-station 130 connectivity at this stage. For efficient operation, both the macro-base-station 110 and the associated pico-base-station 130 can use either LTE FDD or LTE TDD operation, but both should preferably use the same.

III. Macro assisted carrier with dual connectivity.

The third illustrated deployment scenario is denoted 103 in Fig. 4. According to this deployment scenario, a UE capable of carrier aggregation (CA) (i.e. a Rel. 10 or 11 UE or an advanced UE) can detect and camp on a macro-cell that is serviced by a macro-base-station 110. The said UE first establishes RRC connection with the mobile network through the macro-base-station 110. Then, via dedicated RRC signalling through the macro-base-station 110, the said UE is configured to perform small cell measurement serviced by the pico-base-station 140 and to report the measurement result through the macro-base-station 110. Once all conditions for signal reception and transmission with the pico-base-station 140 are satisfied, the said UE, via dedicated RRC signalling through the macro-base-station 110, is configured to establish a second connectivity with pico-base-station 140 for user plane data transmission and reception while maintaining the first connectivity with the macro-base-station 110 for control plane data (RRC signalling) transmission and reception. For efficient operation, the first connectivity with the macro-base-station 110 for control plane data transmission and reception should be deployed with LTE FDD whereas the second connectivity with the pico-base-station 140 for user plane data transmission and reception may be deployed with either LTE-FDD or LTE-TDD.

IV. Standalone carrier

The fourth illustrated deployment scenario is denoted 104 in Fig. 4. According to this fourth deployment scenario, a UE (i.e. a Rel. 8, 9, 10, 11 UE or advanced UE) within the coverage of a pico-base-station 150 can detect or be assisted to detect and camp on a small cell that is serviced by the pico-base-station 150. The said UE is able to establish RRC connection with the mobile network through the pico-base-station 150 and further establish connectivity with the pico-base-station 150 for user plane data transmission and reception, as can be done through a macro-base-station.

1. New carrier type (NCT): carrier aggregation

Figs. 5A,5B, 6A and 6B illustrate a first embodiment of a new carrier type (NCT), which may be used with the first deployment scenario discussed above, where the NCT is used as an aggregated carrier.

With a view to supporting legacy UEs with carrier aggregation capability (such as Rel. 10 or Rel. 11 UEs), the proposed NCT radio frame comprises time multiplexed subframes of the legacy type (i.e. as discussed above) and a new carrier type, as illustrated in the proposed radio frame structure 200 shown in Fig. 5A.

For FDD systems, and for supporting legacy UEs, a network can configure a pico-base-station 120 (see Fig. 4) to transmit NCT radio frame structure 200 comprising at least two legacy DL subframes, namely subframe #0 and subframe #5. On the said subframes #0 and #5 (210 in Fig. 5B), the pico-base-station 120 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} 211 and synchronisation signal 212. If required, such as in the case of non-cross carrier scheduling or self-scheduling, the pico-base-station 120 may be configured to transmit time domain control signal 213 mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 10, 11 and advanced UE(s). In order to increase control signalling capacity in the case of non-cross carrier scheduling or self-scheduling, the network may also configure pico-base-station 120 to further transmit frequency domain control signal 214 servicing Rel. 11 UE(s) and/or advanced UE(s). According to previously proposed LTE with carrier aggregation, pico-cell cell information that is normally broadcast on PBCH 201 and system information are provided to a UE via dedicated RRC-signalling through a macro-base-station 110. An aspect of this first embodiment is that the network can configure the pico-base-station 120 to silent broadcast signal (i.e. so it does not transmit a broadcast signal) in order to conserve power. Furthermore, for an advanced UE being scheduled for reception of PDSCH on PRBs (physical resource blocks) that are reserved for broadcast signal transmission, the advanced UE can assume that RE(s) (resource elements) reserved for broadcast signal may be used for transmitting its PDSCH.

For the remaining subframes, namely

subframe #

1, 2, 3, 4, 6, 7, 8, and 9, another aspect of this first embodiment is that the pico-base-station 120 is configured to transmit the proposed NCT subframes 220 comprising zero, one or multiple frequency domain control regions 221 which are frequency multiplexed with frequency domain data region(s) 222. An advanced UE 160 will be informed via dedicated RRC-signalling through a macro-base-station 110 of the location of the control regions 221 consisting of EPDCCH for USS (UE specific search space) 223 on which it is required to monitor for control signals intended for it in the case of non-cross carrier scheduling. In the case of non-cross carrier scheduling carrier aggregation, the pico-base-station 120 is configured to further reserve RE(s) within the control regions 221 for mapping of EPHICH 224 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH, and via dedicated RRC-signalling an advanced UE 160 is informed of the EPHICH-config.

By observing traffic to and from legacy UE(s) as well as advanced UE(s) within the coverage of a macro-base-station 110, a mobile network may further configure HetNet pico-base-station(s) 120 to transmit legacy subframe(s) on one or more subframes that belong to subframe set {1, 2, 3, 4, 6, 7, 8, 9}. This is another aspect of this first embodiment. In this case, the pico-base-station 120 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} as subframe #0. If required, such as in the case of non-cross carrier scheduling or self-scheduling, the pico-base-station 120 may be further configured to transmit time domain control signal mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 10, 11 and advanced UE(s). The network may also configure pico-base-station 120 to further transmit frequency domain control signals servicing Rel. 11 UE(s) and/or advanced UE(s). Simultaneous transmission of time domain control signals and frequency domain control signals may not always be necessary.

When there is no data scheduled for transmission and/or reception through the pico-base-station 120 as SCell, the network can configure the pico-base-station 120 to transmit synchronisation signal and CRS on subframe #0 and #5 for the purpose of UE measurement, and this may reduce transmit power by up to 80% in comparison with current LTE systems.

A mobile network may decide to reserve a pico-base-station for servicing only advanced UE(s). In this case, the mobile network may configure the pico-base-station 120 to transmit NCT radio frames comprising time multiplexed subframes of new carrier type, as illustrated in the proposed radio frame structure 300 in Fig. 6A.

Referring to Figs. 6A and 6B, for FDD systems, a network can configure pico-base-station 120 to transmit NCT radio frame structure 300 comprising a NCT subframe design 320 for subframe #0 and #5, and another NCT subframe design 340 for remaining

subframes #

1, 2, 3, 4, 6, 7, 8, and 9 . On subframes #0 and #5, the pico-base-station 120 is configured to transmit zero, one or multiple frequency domain control region(s) 321 which are frequency multiplexed with frequency domain data region(s) 322. In the case of non-cross carrier scheduling carrier aggregation or self-scheduling, an advanced UE 160 will be informed, via dedicated RRC-signalling through macro-base-station 110 on the primary carrier component, of the location of the control regions 321 consisting EPDCCH for USS 323 on which it is required to monitor for control signal intended for it. In the case of non-cross carrier scheduling carrier aggregation, the pico-base-station 120 is configured to further reserve RE(s) within control region 321 for the mapping of EPHICH 324 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH. On subframe #0 and #5, the pico-base-station 120 is configured to transmit synchronisation signals 302 (synchronisations signals #1 and #2 in Fig. 6B) mapping on central 72 sub-carriers of two predetermined OFDM symbols. On subframe #0, the network can further configure pico-base-station 120 to silent broadcast signal (i.e. so it does not transmit a broadcast signal) on PBCH 301 in order to conserve its power. For the remaining subframes, namely

subframe #

1, 2, 3, 4, 6, 7, 8, and 9, the pico-base-station 120 is configured to transmit NCT subframes 340 comprising zero, one or multiple frequency domain control region(s) 341 which are frequency multiplexed with frequency domain data region(s) 342. In the case of non-cross carrier scheduling carrier aggregation, an advanced UE 160 will be informed via dedicated RRC-signalling through macro-base-station 110 of the location of the control regions 341 consisting of EPDCCH for USS (UE specific search space) 343 on which it is required to monitor for control signal intended for it. In the case of non-cross carrier scheduling carrier aggregation, the pico-base-station 120 is configured to further reserve RE(s) within control region 341 for the mapping of EPHICH (344) carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

On any pair of subframes in a NCT radio frame structure 300 that are 5ms apart, such as subframes #0 and #5 as illustrated in structure 300, the pico-base-station 120 is configured to transmit configurable R-CRS (reduced cell specific reference signal: i.e. port 0 CRS) 325 within a network configurable bandwidth 326, preferably 5 MHz or full system bandwidth. The transmission bandwidth for R-CRS should be the same as the carrier or system bandwidth when the carrier bandwidth indicated in the system information is 5 MHz or less. An advanced UE 160 will be informed of the R-CRS bandwidth via dedicated RRC-signalling on the primary component carrier. An advanced UE 160 will also be informed, via dedicated RRC-signalling on primary component carrier, of the paired subframes within a radio frame that are allocated for R-CRS mapping. Optionally, paired subframes within a radio frame that are allocated for R-CRS mapping may be self-decodable using Cell-ID. Based on the physical Cell-ID (PCI), the derivation of paired subframes having R-CRS mapping could perhaps be performed using the following example approach:
-For FDD systems: subframe index = PCI mod 5
-For TDD systems: subframe index = PCI mod 2

When there is no data scheduled for transmission and/or reception through the pico-base-station 120 as SCell, the network can configure the pico-base-station 120 to transmit synchronisation signals on subframe #0 and #5, and R-CRS within a configured bandwidth on a predetermined pair of subframes that are 5ms apart for the purpose of UE measurement, thus further reducing transmit power in comparison with current LTE systems.

2. New carrier type (NCT): Macro assisted carrier in single cell connectivity

Figs. 7A,7B, 8A and 8B illustrate a second embodiment of a new carrier type (NCT), which may be used with the second deployment scenario discussed above, namely where the NCT is used as a macro-assisted carrier in single cell connectivity.

In order to provide limited connectivity support to legacy UEs such as Rel. 8, 9, 10 or Rel. 11 UEs, the NCT radio frame proposed in this embodiment comprises time multiplexed subframes of the legacy type (i.e. as discussed in the Background section above) and a new carrier type, as illustrated in proposed radio frame structure 400 in Fig. 7A.

For FDD systems, and for supporting legacy UEs in macro-assisted pico-cell, a network can configure pico-base-station 130 to transmit NCT radio frame structure 400 comprising at least two legacy subframes, namely subframe #0 and subframe #5. On these subframes 420, the pico-base-station 130 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} 421, synchronisation signal 422, and time domain control signal 423 mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 8, 9, 10, 11 and advanced UE(s). In order to increase control signalling capacity, the network can also configure pico-base-station 130 to further transmit frequency domain control signal 424 servicing Rel. 11 UE(s) and/or advanced UE(s). According to previously proposed LTE with HetNet operation, pico-cell cell information that is normally broadcast on PBCH 401 and system information are provided to a UE via dedicated RRC-signalling through a macro-base-station 110 prior to "switching" or hand over from the macro-base-station 110 to pico-base-station 130. An aspect of this second embodiment is that the network can optionally configure pico-base-station 130 to silent broadcast signal (i.e. so it does not transmit a broadcast signal) and utilise RE(s) reserved for PBCH for scheduling the transmission of PDSCH to advanced UE(s).

For the remaining subframes, namely subframes #1, 2, 3, 4, 6, 7, 8, and 9, the pico-base-station 130 is configured to transmit the proposed NCT subframes 440. This is another aspect of the second embodiment of the invention. The proposed NCT subframes 440 comprise frequency domain control region(s) 441 which are frequency multiplexed with frequency domain data region(s) 442.

According to previously proposed LTE with HetNet operation, information relating to pico-cell transmission such as the cell-ID, the number of CRS ports transmitted on legacy subframes and/or the MBSFN subframe configuration in the pico-cell, are provided to a UE for the purpose of interference mitigation via dedicated RRC-signalling through a macro-base-station 110. Prior to switching over from macro-base-station 110 to pico-base-station 130, an advanced UE 160 will be further informed, via dedicated RRC-signalling through macro-base-station 110, of the following:
-radio frame configuration to indicate legacy subframes and NCT subframes in the NCT radio frame;
-the location of the control regions 441 consisting of EPDCCH for USS (UE specific search space) 443 on which it is required to monitor for control signal intended for it;
-the location of the control regions 441 consisting of EPDCCH for CSS (common search space) 445 on which it is required to monitor for control signal for system information update; and
-the EPHICH-config that indicates the reserve RE(s) within the control region 441 for the mapping of EPHICH 444 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

By observing traffic to and/or from legacy UE(s) as well as advanced UE(s) within coverage of a macro-base-station 110, a mobile network may further configure HetNet pico-base-station 130 to transmit a legacy subframe on one or more subframes that belong to the subframe set {1, 2, 3, 4, 6, 7, 8, 9}. In this case, the pico-base-station 130 is configured to transmit full CRS (cell specific reference signal: R0; or R0 and R1; or R0, R1, R2 and R3) as subframe #0. The pico-base-station 130 may be further configured to transmit time domain control signal mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 10, 11 and advanced UE(s). The network can also configure pico-base-station 130 to further transmit frequency domain control signal servicing Rel. 11 UE(s) and/or advanced UE(s). Simultaneous transmission of time domain control signal and frequency domain control signal may not always be necessary. Change in NCT radio frame configuration while a UE still maintains connectivity with the mobile network through pico-base-station 130 will be communicated to that UE via dedicated RRC-signalling using a newly proposed RRC IE (information element) on radio frame configuration to indicate legacy subframes and NCT subframes in the NCT radio frame and/or existing RRC IE 'MeasSubframePattern'. Using the 'MeasSubframePattern' IE, a legacy UE such as Rel. 8, 9, 10 or 11 UE may understand that subframe(s) that it is allowed for measurement is/are legacy subframe(s). Meanwhile an advanced UE may understand that subframe(s) that it is allowed for measurement is/are legacy subframe(s) and other subframes are NCT subframe that may be further scheduled for data reception.

When there is no data scheduled for transmission and/or reception through the pico-base-station 130, the network can configure the pico-base-station 130 to transmit synchronisation signal and CRS on subframe #0 and #5 for the purpose of UE measurement, and this may reduce transmit power by up to 80% in comparison with current LTE systems.

A mobile network may decide to reserve a pico-base-station 130 for servicing only advanced UE(s). In this case, the mobile network may configure the pico-base-station 130 to transmit NCT radio frame comprising time multiplexed subframes of new carrier type, as illustrated in the proposed radio frame structure 500 in Fig. 8A.

Referring to Figs. 8A and 8B, for FDD systems a network can configure pico-base-station 130 to transmit NCT radio frame structure 500 comprising a NCT subframe design 520 for subframe #0 and #5, and another NCT subframe design 540 for remaining

subframes #

1, 2, 3, 4, 6, 7, 8, and 9. On subframes #0 and #5, the pico-base-station 130 is configured to transmit frequency domain control region(s) 521 which is/are frequency multiplexed with frequency domain data region(s) 522. Prior to switching over from macro-base-station 110 to pico-base-station 130, an advanced UE 160 will be informed of the following via dedicated RRC-signalling through macro-base-station 110:
-the location of the control regions 521 consisting of EPDCCH for USS (UE specific search space) 523 on which it is required to monitor for control signal intended for it;
-the location of the control regions 521 consisting of EPDCCH for CSS (common search space) 525 on which it is required to monitor for control signal for system information update; and
-the EPHICH-config that indicates the reserved RE(s) within control region 521 for mapping of EPHICH 524 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

On subframe #0 and #5, the pico-base-station 130 is configured to transmit synchronisation signals 528 (synchronisations signals #1 and #2 in Fig. 8B) mapping on 72 central sub-carriers of two predetermined OFDM symbols. On subframe #0, the network can further configure pico-base-station 130 to silent broadcast signal (i.e. so it does not transmit a broadcast signal) 501 and utilise these RE(s) for PDSCH transmission.

For the remaining subframes, namely subframes #1, 2, 3, 4, 6, 7, 8, and 9, the pico-base-station 130 is configured to transmit NCT subframes 540 comprising frequency domain control region(s) 541 which is/are frequency multiplexed with frequency domain data region(s) 542. Prior to switching over from macro-base-station 110 to pico-base-station 130, an advanced UE 160 will be informed of the following via dedicated RRC-signalling through macro-base-station 110:
-the location of the control regions 541 consisting EPDCCH for USS (UE specific search space) 543 on which it is required to monitor for control signal intended for it;
-the location of the control regions 541 consisting EPDCCH for CSS (Common search space) 545 on which it is required to monitor for control signal for system information update; and
-the EPHICH-config that indicates the reserved RE(s) within control region 541 for the mapping of EPHICH 544 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

On any pair of DL subframes in a NCT radio frame 500 that are 5ms apart, such as subframes #0 and #5, the pico-base-station 130 is configured to transmit R-CRS (reduced cell specific reference signal; i.e. port 0 CRS) 526 within a network configurable bandwidth 527, preferably 5 MHz or full system bandwidth. The transmission bandwidth for R-CRS should be the same as the carrier or system bandwidth when the carrier bandwidth indicated in the system information is 5 MHz or less. An advanced UE 160 will be informed of the R-CRS bandwidth via dedicated RRC-signalling prior to switching over from macro-base-station 110 to pico-base-station 130. An advanced UE 160 will be informed, via dedicated RRC-signalling prior to switching over from macro-base-station 110 to pico-base-station 130, of the paired subframes within a radio frame that are allocated for R-CRS mapping. Optionally, paired subframes within a radio frame that are allocated for R-CRS mapping may be self-decodable using Cell-ID. Based on the physical cell ID (PCI), the derivation of paired subframes having R-CRS mapping could perhaps be performed using the following example approach:
-For FDD system: subframe index = PCI mod 5
-For TDD system: subframe index = PCI mod 2

When there is no data scheduled for transmission and/or reception through the pico-base-station 130 as macro assisted cell, the network can configure the pico-base-station 130 to transmit synchronisation signal on subframe #0 and #5, and R-CRS within a configured bandwidth on a predetermined pair of subframes that are 5ms apart for the purpose of RRM measurement, hence further reducing transmit power in comparison with current LTE systems.

3. New carrier type (NCT): Macro assisted carrier in dual cell connectivity

Figs. 7A, 7b, 8A and 8B can also be used to illustrate a third embodiment of a new carrier type (NCT), which may be used with the third deployment scenario discussed above, where the NCT is used as a macro-assisted carrier in dual cell connectivity.

In order to provide limited connectivity support to legacy UEs with carrier aggregation capability (such as Rel. 10 or Rel. 11 UEs), the proposed NCT radio frame comprises time multiplexed subframes of legacy type (as discussed in the Background section above) and new carrier type, as illustrated in the proposed radio frame structure 400 in Fig. 7A.

For FDD systems, and for supporting legacy UEs as macro-assisted pico-cell, a network can configure a pico-base-station 140 to transmit a NCT radio frame structure 400 comprising at least two legacy subframes, namely subframe #0 and subframe #5. On these subframes 420, the pico-base-station 140 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} 421, synchronisation signal 422, and (if required) time domain control signal 423 mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 10, 11 and advanced UE(s). In order to increase control signalling capacity, the network can also configure pico-base-station 140 to transmit frequency domain control signal 424 servicing Rel. 11 UE(s) and/or advanced UE(s) with or without time domain control. According to previously proposed LTE with HetNet operation, pico-cell cell information that is normally broadcast on PBCH 401 and system information are provided to a UE via dedicated RRC-signalling through macro-base-station 110 prior to establishing the connectivity (the second connectivity) with pico-base-station 140 for user plane data transmission and reception. An aspect of the third embodiment is that the network can configure pico-base-station 140 to silent broadcast signal (i.e. so it does not transmit broadcast signal) and utilise RE(s) reserved for PBCH for scheduling the transmission of PDSCH carrying user plane data to advanced UE(s).

For the remaining subframes, namely subframes #1, 2, 3, 4, 6, 7, 8, and 9, the pico-base-station 140 is configured to transmit the proposed NCT subframes 440. This is another aspect of the third embodiment of the invention. The proposed NCT subframes 440 comprise one or more frequency domain control regions 441 which are frequency multiplexed with frequency domain data region(s) 442.

An advanced UE 160 will be informed of the following, via dedicated RRC-signalling through the macro-base-station 110 on the first connectivity:
-the location of the control regions 441 consisting of EPDCCH for USS 443 on which it is required to monitor for control signals intended for it;
-the location of the control regions 441 consisting of EPDCCH for CSS 445 on which it is required to monitor for control signal for system information update; and
-the EPHICH-config that indicates the reserved RE(s) within control region 441 for mapping of EPHICH 444 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

By observing traffic to and/or from legacy UE(s) as well as advanced UE(s) within coverage of a macro-base-station 110, a mobile network may further configure HetNet pico-base-station 140 to transmit a legacy subframe on one or more subframes that belong to subframe set {1, 2, 3, 4, 6, 7, 8, 9}. In this case, the pico-base-station 140 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} as subframe #0. If required, the pico-base-station 140 may be further configured to transmit time domain control signal mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 10, 11 and advanced UE(s). The network can also configure pico-base-station 140 to further transmit frequency domain control signal servicing Rel. 11 UE(s) and/or advanced UE(s) with or without time domain control signal. Change in NCT radio frame configuration while a UE still maintains dual connectivity with the mobile network through macro-base-station 110 and pico-base-station 140 will be communicated to that UE via dedicated RRC-signalling through macro-base-station 110 using RRC IE (information element) 'MeasSubframePattern'. Using the 'MeasSubframePattern' IE, a legacy UE such as a Rel. 10 or 11 UE may understand that subframe(s) that it is allowed for measurement is/are legacy subframe(s). Meanwhile, an advanced UE may understand that subframe(s) that it is allowed for measurement is/are legacy subframe(s) and other remaining subframes are NCT subframes that may be further scheduled for user plane data reception.

When there is no user plane data scheduled for transmission and/or reception through the pico-base-station 140, the network can configure the pico-base-station 140 to transmit synchronisation signal and CRS on subframes #0 and #5 for the purpose of RRM measurement and this may reduce transmit power by up to 80% in comparison with current LTE systems.

A mobile network may decide to reserve a pico-base-station 140 for servicing advanced UE(s) only. In this case, the mobile network may configure the pico-base-station 140 to transmit NCT radio frame comprising time multiplexed subframes of new carrier type, as illustrated in the proposed radio frame structure 500 in Fig. 8B.

Referring to Figs. 8A and 8B, for FDD systems a network can configure pico-base-station 140 to transmit NCT radio frame structure 500 comprising a NCT subframe design 520 for subframe #0 and #5, and another NCT subframe design 540 for remaining

subframes #

1, 2, 3, 4, 6, 7, 8, and 9. On subframes #0 and #5, the pico-base-station 140 is configured to transmit one or more frequency domain control regions 521 which is/are frequency multiplexed with frequency domain data region(s) 522. An advanced UE 160 will be informed of the following via dedicated RRC-signalling through macro-base-station 110 connectivity:
-the location of the control regions 521 consisting EPDCCH for USS (UE specific search space) 523 on which it is required to monitor for control signal intended for it;
-the location of the control regions 521 consisting EPDCCH for CSS (Common search space) 525 on which it is required to monitor for control signal for system information update; and
-the EPHICH-config that indicates the reserve RE(s) within control region 521 for the mapping of EPHICH 524 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

On subframes #0 and #5, the pico-base-station 140 is configured to transmit synchronisation signals 528 mapping on 72 central sub-carriers of two predetermined OFDM symbols. On subframe #0, the network can further configure pico-base-station 140 to silent broadcast signal (i.e. so it does not transmit a broadcast signal) 501 and utilise these RE(s) for PDSCH carrying user plane data transmission.

For the remaining subframes, namely subframes #1, 2, 3, 4, 6, 7, 8, and 9, the pico-base-station 140 is configured to transmit NCT subframes 540 comprising frequency domain control region(s) 541 which are frequency multiplexed with frequency domain data region(s) 542. An advanced UE 160 will be informed of the following via dedicated RRC-signalling through macro-base-station 110 connectivity:
-the location of the control regions 541 consisting EPDCCH for USS (UE specific search space) 543 on which it is required to monitor for control signal intended for it;
-the location of the control regions 541 consisting EPDCCH for CSS (Common search space) 545 on which it is required to monitor for control signal for system information update; and
-the EPHICH-config that indicates the reserve RE(s) within control region 541 for the mapping of EPHICH 544 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

On any pair of subframes in a NCT radio frame 500 that are 5ms apart, such as subframes #0 and #5 as illustrated in structure 520, the pico-base-station 140 is configured to transmit configurable R-CRS (Reduced cell specific reference signal i.e. port 0 CRS) 526 within a network configurable bandwidth 527 preferably 5 MHz or full system bandwidth. The transmission bandwidth for R-CRS should be the same as the carrier or system bandwidth when the carrier bandwidth indicated in the system information is 5 MHz or less. An advanced UE 160 will be informed of the R-CRS bandwidth via dedicated RRC-signalling through macro-base-station 110 connectivity. An advanced UE 160 will be informed, via dedicated RRC-signalling through macro-base-station 110 on the first connectivity, of the paired subframes within a radio frame that are allocated for R-CRS mapping. Optionally, paired subframes within a radio frame that are allocated for R-CRS mapping may be self-decodable using Cell-ID. Based on the physical cell ID (PCI), the derivation of paired subframes having R-CRS mapping may be done using the following example approach:
-For FDD system: subframe index = PCI mod 5
-For TDD system: subframe index = PCI mod 2

When there is no user plane data scheduled for transmission and/or reception through the pico-base-station 140 as macro assisted cell in dual cell connectivity, the network can configure the pico-base-station 140 to transmit a synchronisation signal on subframe #0 and #5, and R-CRS within a configured bandwidth on a predetermined pair of subframes that are 5ms apart for the purpose of RRM measurement, hence further reducing transmit power in comparison to current LTE system.

4. New carrier type (NCT): Standalone carrier

Figs. 7A, 7B, 8A and 8B can again be used to illustrate a fourth embodiment of new carrier type (NCT), which may be used with the fourth deployment scenario discussed above, where the disclosed NCT design is used as non-macro-assisted carrier or standalone carrier.

As for any standalone carrier, a cell that operates on the standalone carrier shall be initially detectable by a UE cell search procedure. In order to provide limited connectivity support to legacy UEs (such as Rel. 8, 9, 10 or Rel. 11 UEs) the proposed NCT radio frame comprises time multiplexed subframes of a legacy type and new carrier type, as illustrated in the proposed radio frame structure 400 in Fig. 7A.

For FDD systems, and for supporting legacy UEs in the non-macro-assisted or standalone pico-cell scenario, a network can configure pico-base-station 150 to transmit NCT radio frame structure 400 comprising at least four legacy subframes, namely subframe #0, subframe #5, subframe #4 and subframe #9 (for TDD systems,

subframes #

0, 1, 5 and 6 are recommended). On subframes #0 and #5 420, the pico-base-station 150 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} 421 and legacy synchronisation signal 422. Based on the transmitted synchronisation signal, a legacy UE such as Rel. 8, 9, 10 or 11 UE or advanced UE can detect the pico-cell cell-ID and associated timing. On subframe #0, the pico-base-station 150 is further configured to transmit a legacy cell broadcast signal on PBCH 401 for a legacy UE or advanced UE to know cell system information such as system bandwidth, system frame number and PHICH information. On subframes #0 and #5, the pico-base-station 150 is configured to transmit time domain control signal comprising PDCCH CSS assisting a UE to further receive system information (i.e. SIB). On subframes #4 and #9, the pico-base-station 150 is configured to transmit full configured CRS {Cell specific reference signal: R0 (i.e. port 0); or R0 and R1 (i.e. port 0 and port 1); or R0, R1, R2 and R3 (i.e. port 0, port 1, port 2 and port 3)} as per subframe #0. The pico-base-station 150 may be further configured to transmit time domain control signal mapping on the first 1, 2, 3 or 4 OFDM symbols servicing Rel. 8, 9, 10, 11 and advanced UE(s). The network can also configure pico-base-station 150 to further transmit frequency domain control signal servicing Rel. 11 UE(s) and/or advanced UE(s). NCT radio frame structure 400 comprising at least four

legacy subframes #

0, 4, 5 and 9 is sufficient for legacy UE(s) and advanced UE(s) to establish RRC connection through pico-cell 150. In the RRC-connected state, a legacy UE will be scheduled for data reception on the set of subframes {0, 4, 5, 9}. For the remaining subframes, namely subframes #1, 2, 3, 6, 7 and 8, the pico-base-station 150 is configured to transmit the proposed NCT subframes 440. The proposed NCT subframes 440 comprise frequency domain control region(s) 441 which are frequency multiplexed with frequency domain data region(s) 442. An advanced UE 160 will be informed of the following via dedicated RRC-signalling through pico-base-station 150:
-the location of the control regions 441 consisting EPDCCH for USS (UE specific search space) 443 on which it is required to monitor for control signal intended for it; and
-the EPHICH-config that indicates the reserve RE(s) within control region 441 for the mapping of EPHICH 444 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH

When there is no data scheduled for transmission and/or reception through the pico-base-station 150 as a standalone cell, the network can configure the pico-base-station 150 to transmit synchronisation signal and broadcast signal on subframe #0 and #5, and CRS on subframe #0, #4, #5, and #9 for the purpose of UE measurement, and this may reduce transmit power by up to 60% in comparison with current LTE systems.

A mobile network may decide to reserve a pico-base-station 150 for servicing only advanced UE(s). In this case, the mobile network may configure the pico-base-station 150 to transmit NCT radio frame comprising time multiplexed subframes of new carrier type, as illustrated in the proposed radio frame structure 500 in Fig. 8B.

On subframes #0 and #5, the pico-base-station 150 is configured to transmit synchronisation signals 528 mapping on 72 central sub-carriers of two predetermined OFDM symbols. Based on the synchronisation signals 528 mapping on central 72 sub-carriers of two predetermined OFDM symbols, an advanced UE 160 can detect the pico-cell cell-ID and associated timing. A legacy UE may be able to detect the pico-cell cell-ID and associated timing if the two predetermined OFDM symbols are the same as that for legacy system.

Since, a legacy UE is barred from accessing pico-base-station 150 in this case, on subframe #0, as one aspect of the fourth embodiment of the invention, pico-cell cell broadcast signal (MIB) transmitted on PBCH (501) may be mapped on predetermined PRB pairs within central six PRBs that are known only to advanced UE(s). In this case, a legacy UE will not be able to access cell information of pico-base-station 150. MIB broadcast on PBCH will preferably have the same structure as in previously proposed 3GPP LTE. Additionally, the broadcast MIB further comprises information on R-CRS bandwidth (Reduced cell specific reference signal i.e. port 0 CRS) preferably using two spare bits to indicate 5 MHz or full system bandwidth for R-CRS. The unitisation of the two spare bits in the current MIB may comprise the following:
-00 : reserved;
-01 : centre 25 PRBs;
-10 : full carrier BW; and
-11 : zero PRBs or no transmission.

The transmission bandwidth for R-CRS should be the same as the carrier bandwidth when the carrier bandwidth indicated in the system information is 5MHz or lower. On any pair of subframes in a NCT radio frame 500 that are 5ms apart, such as subframe #0 and #5 as illustrated in structure 520, the pico-base-station 150 is configured to transmit configurable R-CRS (Reduced cell specific reference signal i.e. port 0 CRS) 526 within a network configurable bandwidth 527 and to broadcast on MIB. An advanced UE 160 will use detected Cell-ID to derive paired subframes within a radio frame that are allocated for R-CRS mapping (i.e. self-decodable using Cell-ID). Based on the physical cell ID (PCI), the derivation of paired subframes having R-CRS mapping can be done using the following example approach:
-For FDD system: subframe index = PCI mod 5; and
-For TDD system: subframe index = PCI mod 2

On every subframe in a radio frame, a network can configure pico-base-station 150 to transmit one or more frequency domain control regions 521 which are frequency multiplexed with frequency domain data region(s) 522. For a control region 521 consisting of EPDCCH for CSS (common search space) 525 or a control region 521 consisting EPDCCH for CSS and USS (UE specific search space) 523, the pico-base-station 150 shall transmit this control region on PRB pair(s) that can be blind detected by an advanced UE.

In RRC-connected mode, an advanced UE 160 will be further informed, via dedicated RRC-signalling, of the location of other control regions 521 consisting of EPDCCH for USS 523 on which it is required to monitor for control signal intended for it, and of the reserved RE(s) within the control regions 521 for the mapping of EPHICH 524 carrying H-ARQ ACK corresponding to advanced UE transmitted UL-SCH.

When there is data scheduled for transmission and/or reception through the pico-base-station 150 as a standalone carrier, the network can configure the pico-base-station 150 to transmit synchronisation signal and broadcast signal on subframe #0 and #5, and R-CRS within a configured bandwidth on a predetermined pair of subframes that are 5ms apart for the purpose of RRM measurement, hence further reducing transmit power in comparing to current LTE system.

A number of potential advantages of the present invention are discussed below.

Designating certain downlink subframes on the NCT carrier as legacy subframes, in which legacy full CRS ports, control channels, broadcast PBCH, and synchronisation signals can be selectively transmitted, provides support for the operation of legacy UEs (i.e. it allows legacy UEs to receive downlink data scheduling in legacy subframes and to transmit in UL carrier component) on the NCT carrier.

Time multiplexing of legacy subframes and the newly proposed NCT subframes (which together form the newly proposed first NCT radio frame) may help to enable a greater number of UEs in the network on NCT carriers and also to provide more flexible scheduling of downlink data for UEs. This may also allow the mobile network to better offload data traffic from different UEs, hence improving user experienced throughput and load balancing between carriers.

Transmission of synchronisation and system information broadcast signal may be turned off in some operating scenarios. This may help to reduce network energy consumption and to reduce inter-cell interference. In some cases the reserved radio resources may also be reused for downlink data transmission to achieve higher data rates.

Flexible configuration of reduced-CRS transmission bandwidth may allow higher downlink data rates when the minimum bandwidth is configured and improve measurement accuracy when transmitting in full system bandwidth.

Flexible configuration of reduced-CRS transmission subframes may help to support time domain inter-cell interference coordination (ICIC).

Base-station assistance information may help advanced UEs to mitigate inter-cell interference for better support of NCT carrier operating in HetNet co-channel deployment.

In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises' and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

The above-mentioned processing may be executed by a computer, for example, an access node and a user equipment. Also, it is possible to provide a computer program which causes a programmable computer device to execute the above-mentioned processing. The program can be stored and provided to a computer using any type of non-transitory computer readable media. Non-transitory computer readable media include any type of tangible storage media. Examples of non-transitory computer readable media include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), optical magnetic storage media (e.g. magneto-optical disks), CD-ROM, CD-R, CD-R/W, and semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory), etc.). The software modules may be provided to a computer using any type of transitory computer readable media. Examples of transitory computer readable media include electric signals, optical signals, and electromagnetic waves. Transitory computer readable media can provide the software modules to a computer via a wired communication line (e.g. electric wires, and optical fibers) or a wireless communication line.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

For example, the present invention can be implemented in the following forms.
(1) A signaling method for use in an advanced wireless communications network, wherein the network is a heterogeneous network including at least one first access node and at least one second access node, the first and second access nodes being operable to communicate with legacy user equipments (UEs) and advanced UEs, the method comprising:
transmitting legacy radio frames from the first access node, and
transmitting new carrier type (NCT) radio frames from the second access node,
wherein the NCT radio frames include one or both of
first radio frames operable to support legacy UEs and advanced UEs, and second radio frames operable to support advanced UEs only.
(2) The signaling method according to Item (1), wherein the first access node provides a primary component carrier (PCell) for data reception and transmission by a UE, and the second access node provides a secondary component carrier (SCell) as an aggregated carrier for additional data reception and transmission by the UE.
(3) The signaling method according to Item (2), wherein the legacy radio frames transmitted by the first access node and the NCT radio frames transmitted by the second access node are one of the following: frequency division duplex (FDD) and time division duplex (TDD) respectively, TDD and FDD respectively, TDD and TDD respectively, or FDD and FDD respectively.
(4) The signaling method according to Item (1), wherein the first access node provides wireless connectivity for a UE to establish control plane communication through the first access node before the UE switches connectivity to the second access node whereupon the UE establishes data plane communication and continues to maintain the said control plane communication through the second access node.
(5) The signaling method according to Item (4), wherein the legacy radio frames transmitted by the first access node and the NCT radio frames transmitted by the second access node are one of the following: FDD and FDD respectively, or TDD and TDD respectively.
(6) The signaling method according to Item (1), wherein the first access node provides wireless connectivity for a UE to establish a first connectivity for control plane communication through the first access node, and the first access node assists the UE to establish a second connectivity for data plane communication through the second access node, whereupon the UE conducts data plane communication through the second access node but conducts control plane communication through the first access node.
(7) The signaling method according to Item (6), wherein the legacy radio frames transmitted by the first access node and the NCT radio frames transmitted by the second access node are one of the following: FDD and TDD respectively, FDD and FDD respectively, or TDD and TDD respectively.
(8) The signaling method according to Item (1), wherein a UE detects the second access node during cell search without or with assistance from the first access node and conducts data communication through the second access node.
(9) The signaling method according to Item (8), wherein the NCT radio frames transmitted by the second access node are FDD or TDD.
(10) The signaling method according to any one of the preceding Items wherein, in the NCT radio frames transmitted by the second access node, each first radio frame comprises one or more subframes of legacy type which is/are time multiplexed with subframes of new carrier type.
(11) The signaling method according to Item (10), wherein each first radio frame comprises ten subframes numbered #0, #1, #2,..., #9, two of which are subframes of legacy type.
(12) The signaling method according to Item (11), wherein the first of the subframes of legacy type is subframe #0 and the second of the subframes of legacy type is subframe #5 for a FDD system.
(13) The signaling method according to Item (11), wherein the first of the subframes of legacy type comprises a cell specific reference signal (CRS).
(14) The signaling method according to Item (13), wherein the first of the subframes of legacy type further comprises none, one or both of a synchronization signal and a broadcast signal.
(15) The signaling method according to Item (11), wherein the second of the subframes of legacy type comprises a CRS.
(16) The signaling method according to Item (15), wherein the second of the subframes of legacy type further optionally comprises a synchronization signal.
(17) The signaling method according to any one of Items (11) to (16) wherein, by observing traffic to and/or from one or more legacy UEs and/or advanced UEs, the advanced network can further configure a third or more subframes of legacy type in a first radio frame.
(18) The signaling method according to Item (17) wherein, in the case of a self-scheduling carrier, the advanced network includes a time domain control region on one or more of the first, second and third subframes of legacy type.
(19) The signaling method according to Item (18), wherein the advanced network includes a frequency domain control signal on one or more subframes of legacy type.
(20) The signaling method according to any one of Items (10)-(19) wherein, among the first radio frames in a NCT radio frame transmitted by the second access node, the subframes of new carrier type comprise zero, one or more frequency domain control regions which are frequency multiplexed with one or more frequency domain data regions.
(21) The signaling method according to any one of the preceding Items wherein, in the NCT radio frames transmitted by the second access node, each second radio frame comprises time multiplexed new carrier type subframes.
(22) The signaling method according to Item (21), wherein each second radio frame comprises ten subframes numbered #0, #1, #2,..., #9, and synchronisation signals are optionally transmitted on the subframes #0 and #5.
(23) The signaling method according to Item (22) wherein, in the new carrier type subframes of a second radio frame, broadcast signals are optionally transmitted on subframe #0.
(24) The signaling method according to Item (23) wherein, in the new carrier type subframes of a second radio frame, a frequency domain data region is transmitted on all subframes.
(25) The signaling method according to Item (24), wherein resource element(s) (RE(s)) reserved for transmitting a broadcast signal are utilised by advanced UEs for reception of physical downlink shared channel (PDSCH).
(26) The signaling method according to Item (24) wherein, in the new carrier type subframes of a second radio frame, for a self-scheduled carrier, one or more frequency domain control regions are transmitted on all subframes.
(27) The signaling method according to Item (19), (20) or (26), wherein a said frequency domain control region includes enhanced physical downlink control channel (EPDCCH) for UE specific search space (USS).
(28) The signaling method according to Item (27), wherein a said frequency domain control region further includes REs reserved for the mapping of EPHICH carrying HARQ-ACK corresponding to previously transmitted uplink shared channel (UL-SCH).
(29) The signaling method according to Item (28), wherein a UE is informed via dedicated RRC-signalling of the location of a frequency domain control region and of EPHICH-configuration.
(30) The signaling method according to Item (21), wherein a radio frame has a 10ms duration, each of subframes #0, #1, #2,..., #9 has a 1ms duration, and on any pair of subframes that are 5ms apart, an advanced network is able to configure transmission of reduced CRS (R-CRS) of port 0 CRS within 5 MHz or full system bandwidth.
(31) The signaling method according to Item (30), wherein if the system bandwidth is 5 MHz or less, the bandwidth of R-CRS is the same as the system bandwidth.
(32) The signaling method according to Item (30), wherein for a non-standalone carrier, a UE is informed via dedicated RRC-signalling of the R-CRS bandwidth and the subframe on which R-CRS is mapped.
(33) The signaling method according to Item (30), wherein for a standalone carrier, the R-CRS bandwidth is broadcast utilising 2 spare bits wherein '00' indicates reserved, '01' indicates 5 MHz, '10' indicates full bandwidth and '11' indicates no R-CRS.
(34) The signaling method according to Item (30), wherein a pair of subframes is allocated for R-CRS mapping and is self-decodable using a MOD function of a predefined variable (such as 2 or 5, for example).
(35) The signaling method according to Item (26) wherein, if the NCT radio frames are deployed as a macro-assisted carrier or a standalone carrier, the advanced network is able to configure one or more frequency domain control regions to include EPDCCH for common search space (CSS).
(36) The signaling method according to Item (35) wherein, if the NCT radio frames are deployed as a macro-assisted carrier, an advanced UE is informed via dedicated RRC-signalling of the location of the frequency domain control region(s) having EPDCCH for CSS.
(37) The signaling method according to Item (35) wherein, if the NCT radio frames are deployed as a standalone carrier, the advanced wireless network will configure transmission of the control region(s) on PRB pair(s) that can be blind detected by an advanced UE.
(38) The signaling method according to Item (13)-(17) wherein, if the NCT radio frames are deployed as a macro-assisted carrier, an advanced UE is informed via dedicated RRC-signalling of the details of CRS on subframes of legacy type and of radio frame configuration to indicate subframes of legacy type and subframes of NCT within a first radio frame.

This application is based upon and claims the benefit of priority from Australian provisional patent application No.2013902969, filed on August 8, 2013, the disclosure of which is incorporated herein in its entirely by reference.

100 ADVANCED WIRELESS COMMUNICATION SYSTEM
101 to 104 DEPLOYMENT SCENARIO
110 MACRO-BASE-STATION
120 to 150 PICO BASE STATION
160 USER EQUIPMENT
200 RADIO FRAME STRUCTURE
201 PBCH
210 SUBFRAME
211 CRS (CELL SPECIFIC REFERENCE SIGNAL)
212 SYNCHRONISATION SIGNAL
213 TIME DOMAIN CONTROL SIGNAL
214 FREQUENCY DOMAIN CONTROL SIGNAL
220 NCT SUBFRAME
221 CONTROL REGION
222 DATA REGION
223 EPDCCH FOR USS
224 EPHICH
300 RADIO FRAME STRUCTURE
301 PBCH
302 SYNCHRONISATION SIGNAL
320 NCT SUBFRAME
321 CONTROL REGION
322 DATA REGION
323 EPDCCH FOR USS
324 EPHICH
325 R-CRS (REDUCED CELL SPECIFIC REFERENCE SIGNAL)
326 NETWORK CONFIGURABLE BANDWIDTH
340 NCT SUBFRAME
341 CONTROL REGION
342 DATA REGION
343 EPDCCH FOR USS
344 EPHICH
400 RADIO FRAME STRUCTURE
401 PBCH
420 SUBFRAME
421 CRS
422 SYNCHRONISATION SIGNAL
423 TIME DOMAIN CONTROL SIGNAL
424 FREQUENCY DOMAIN CONTROL SIGNAL
441 NCT SUBFRAME
442 DATA REGION
443 EPDCCH FOR USS
444 EPHICH
445 EPDCCH FOR CSS
500 RADIO FRAME STRUCTURE
501 PBCH
520 NCT SUBFRAME
521 CONTROL REGION
522 DATA REGION
523 EPDCCH FOR USS
524 EPHICH
525 EPDCCH FOR CSS
526 R-CRS
527 NETWORK CONFIGURABLE BANDWIDTH
540 NCT SUBFRAME
541 CONTROL REGION
542 DATA REGION
543 EPDCCH FOR USS
544 EPHICH
545 EPDCCH FOR CSS
F1 FIRST CARRIER FREQUENCY
F2 SECOND CARRIER FREQUENCY

Claims

In a wireless communications network including a first access node and a second access node, a method implemented in the second access node, the method comprising:
transmitting new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
wherein the first access node transmits legacy radio frames.
The method as claimed in claim 1, wherein the first access node provides a primary component carrier (PCell), and the second access node provides a secondary component carrier (SCell) as an aggregated carrier.
The method as claimed in claim 2, wherein the legacy radio frames and the NCT radio frames are one of the followings: frequency division duplex (FDD) and time division duplex (TDD) respectively, TDD and FDD respectively, TDD and TDD respectively, or FDD and FDD respectively.
The method as claimed in claim 1, wherein the first access node provides wireless connectivity for a UE to establish control plane communication through the first access node before the UE switches connectivity to the second access node whereupon the UE establishes data plane communication and continues to maintain the said control plane communication through the second access node.
The method as claimed in claim 4, wherein the legacy radio frames and the NCT radio frames are one of the followings: FDD and FDD respectively, or TDD and TDD respectively.
The method as claimed in claim 1, wherein the first access node provides wireless connectivity for a UE to establish a first connectivity for control plane communication through the first access node, and the first access node assists the UE to establish a second connectivity for data plane communication through the second access node, whereupon the UE conducts data plane communication through the second access node but conducts control plane communication through the first access node.
The method as claimed in claim 6, wherein the legacy radio frames and the NCT radio frames are one of the followings: FDD and TDD respectively, FDD and FDD respectively, or TDD and TDD respectively.
The method as claimed in claim 1, wherein a UE detects the second access node during cell search without or with assistance from the first access node and conducts data communication through the second access node.
The method as claimed in claim 8, wherein the NCT radio frames are FDD or TDD.
The method as claimed in claim 1, wherein the first radio frame comprises one or more legacy type subframes of which are time-multiplexed with new carrier type subframes.
The method as claimed in claim 10, wherein, in the first radio frame, the new carrier type subframes comprise zero, one, or more frequency domain control regions which are frequency-multiplexed with one or more frequency domain data regions.
The method as claimed in claim 1, wherein the second radio frame comprises time-multiplexed new carrier type subframes.
In a wireless communications network including a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation, a method implemented in the second UE, the method comprising:
receiving, from a second access node, new carrier type (NCT) radio frames including:
a first radio frame operable to support the first user equipment (UE) and the second UE; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
wherein a first access node transmits legacy radio frames.
A method implemented in a wireless communications network including a first access node and a second access node, the method comprising:
transmitting, from the second access node, new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
transmitting, from the first access node, legacy radio frames.
An access node used in a wireless communications network, the access node comprising:
a transmitter to transmit new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE,
wherein another access node in the wireless communications network transmits legacy radio frames.
A user equipment (UE) capable of carrier aggregation and used in a wireless communications network including a first access node and a second access node, the UE comprising:
a receiver to receive, from the second access node, new carrier type (NCT) radio frames including:
a first radio frame operable to support the user equipment (UE) and another UE incapable of carrier aggregation; and
a second radio frame inoperable to support the UE and operable to support said another UE,
wherein the first access node transmits legacy radio frames.
A wireless communications network comprising:
a first access node transmitting legacy radio frames;
a second access node transmitting new carrier type (NCT) radio frames including:
a first radio frame operable to support a first user equipment (UE) incapable of carrier aggregation and a second UE capable of carrier aggregation; and
a second radio frame inoperable to support the first UE and operable to support the second UE.