KR101581601B1 - Methods of channel state information feedback and transmission in coordinated multipoint wireless communications system - Google Patents

Abstract

An apparatus and method are provided for feedback solutions that work together with CoMP transmissions. Feedback solutions can be applied for joint transmission (JT) as well as cooperative scheduling (CS) and cooperative non-forming (CB). Embodiments of the present disclosure are described herein with respect to wireless LTE according to LTE standards.

Description

[0001] METHODS OF CHANNEL STATE INFORMATION FEEDBACK AND TRANSMISSION IN COORDINATED MULTIPOINT WIRELESS COMMUNICATIONS SYSTEM [0002] FIELD OF THE INVENTION [0003]

This application is a continuation-in-part of U.S. Provisional Patent Application No. 61 / 523,056 filed on August 12, 2011, U.S. Patent Application No. 61 / 541,387 filed on September 30, 2011, U.S. Patent Application No. 13 / 545,632, the contents of which are hereby incorporated by reference.

The present disclosure relates generally to communication systems and more particularly to channel state information feedback and data transmission in cooperative multi-point (CoMP) wireless communication systems.

In known wireless telecommunication systems, a transmitting equipment or access device in a base station transmits signals through a geographical area known as a cell. As technology advances, more advanced equipment has been introduced that can provide services that were not previously possible. Such advanced equipment includes, for example, E-UTRAN (evolved universal terrestrial radio access network) Node B (eNB), base station or other systems and devices. Such advanced or next generation equipment is often referred to as long-term evolution (LTE) equipment, and packet-based networks that utilize such equipment are often referred to as the Evolved Packet System (EPS). An access device may include any component, such as a conventional base station or an LTE eNB (an evolved node B), which may provide access to other components in a telecommunications system to a user equipment (UE) or mobile equipment (ME) do.

Cooperative multi-point (CoMP) transmission and reception is one solution for providing a more ubiquitous experience in wireless communication systems, especially for users at the cell-edge. In known CoMP systems, the feedback process is often designed based on single cell non-cooperative scenarios, and additional feedback may be required in some scenarios.

In light of the following detailed description taken in conjunction with the following drawings, it is to be understood that the disclosure is to be understood and numerous objects, features and advantages of the disclosure may be obtained.
1 shows a block diagram of an embodiment of a wireless network having a Remote Radio Head (RRH) deployment.
2 shows a block diagram of an embodiment of a wireless network having a homogeneous network arrangement.
3 illustrates a block diagram of procedures for downlink data transmission between an eNB and a UE according to one embodiment.
Figures 4A-4C show block diagrams of CSI-RS pattern examples.
5 illustrates a flow diagram of a transmission block processing method for a downlink shared channel in accordance with one embodiment.
6 shows a schematic block diagram of a physical layer of a wireless device for physical channel processing in accordance with one embodiment.
FIG. 7 shows a block diagram of an example of a CSI-RS configuration for four nodes in a cell, each having two antenna ports.
Figure 8 shows a block diagram of an example of a TP specific CSI-RS configuration.
Figure 9 shows a block diagram of an example of joint transmission from multiple TPs with mixed ranks.
Figure 10 shows a block diagram of an example of transmit diversity distributed non-beamformed.
11 shows a block diagram of an example of Rank 2 data transmission using Tx diversity over two TPs, each having two antennas.
Figure 12 shows a block diagram of an example of resource allocation in separate sub-band transmission modes.
Figure 13 shows a flow diagram of an example of CoMP code word splitting for a single codeword.
Figure 14 shows a flow diagram of an example of transport block processing for repeating the output of a channel encoder on separate sub-bands.
15 shows a block diagram of CSI feedback for closed-loop CoMP transmission.
Figure 16 shows a block diagram of an example of the sharing of the CSI configuration between different RRHs.
Figure 17 shows a block diagram of an example of a CSI-RS configuration.
18 shows a block diagram of a wireless device according to one embodiment.
Figure 19 illustrates a wireless-enabled communication environment that includes an embodiment of a client node.
20 is a simplified block diagram of an exemplary client node including a digital signal processor (DSP).
21 is a simplified block diagram of a software environment that may be implemented by a DSP.

An apparatus and method are provided for feedback solutions that work together with CoMP transmissions. Feedback solutions can be applied not only to joint transmissions (JT) but also to cooperative scheduling (CS) and cooperative nonforming (CB). Embodiments of the present disclosure are described herein in the context of a wireless network according to LTE standards, including, but not limited to, Releases 8, 9, and 10. However, those skilled in the art will appreciate that embodiments may be configured for networks of other wireless standards.

More specifically, in one embodiment, the feedback solution includes a Per Transmission Point (TP) Precoding Matrix Indicator (PMI), a Per TP (Per Transmission Point) (RI) (per TP Rank Indicator (RI)) and per TP and per codeword channel quality indicator (CQI) feedback as well as per codeword joint CQI feedback. The TP may refer to an eNB (Node B), a low power node (LPN) or a remote radio head (RRH). In this embodiment, For the width, the UE determines one PMI and one RI for each configured TP and a non-JT CQI for each TP and a respective codeword (DL data transmission from a separate TP with a corresponding PMI and RI , And / or Feedbacks one JT CQI for each codeword (resulting from assuming a joint transmission from all configured TPs having feedback PMIs and RIs), and the number of codewords is the maximum of the data layers over all TPs is determined by a number. in the case of joint transmission, S _i, and the index by (i = 0, 1, ... N TP- 1) where N is the number of TPs in the _TP COMP set configured for the UE, and precoding in TPi will be subject to pre-defined layer, which is transmitted therefrom, to be able to know if induce S _i from the RIs of how both the eNB and the UE reports accordingly, for dynamically (for example, by the eNB, PDCCH (E.g., through RRC signaling), so that the UE can know the layer allocation for the joint CQI computation, or it can be derived at the UE, It could be signaled by a high-eNB.

In another embodiment, the feedback solution may include per TP PMI, per TP RI, per TP and per codeword CQI feedback and per TP TP phase feedback, and per codeword joint CQI feedback. This embodiment is similar except that the phase offset term relative to each TP is also fed back and the fed-back common (JT) CQI is derived on the assumption that the relative phase offsets are calibrated by the participating TPs , Which is similar to the first embodiment. Thus, for each configured sub-band or for the entire (wide band) system bandwidth, the UE is assumed to: assume PMI and RI per TP, assuming joint transmission, and free from all TPs with feedback PMIs. (Per TP) data with feedback PMI and RI, a relative phase offset term of the per-TPPER data layer assuming a common reference point such that the coded signals are constructively added at the UE receiver, Computes and feeds back a common CQI per codeword assuming a non-JT CQI percoder word TP, assuming transmission, and / or a codeword joint transmission with feedback PMIs, RIs and correction for relative phase offset terms , Where the number of codewords is determined by the maximum number of data layers over all TPs. The layer mapping in each of the TP in the case of joint transmission: eNB and the UE both are pre-defined to know how to derive the S _i on from RIs, and if possible from the other channel state information (CSI), the dynamic by the eNB ( (E. G., Via PDCCH) or semi-statically (e. G., Via RRC signaling) so that the UE is aware of the layer allocation for joint CQI computation, or is derived at the UE And may be signaled from the UE to the eNB.

In another embodiment, the feedback solution may include joint TPQ feedback and joint TPQ feedback, as well as joint TPQ feedback, wherein the UE feeds back a single common RI for all TPs instead of per TP RI.

In another embodiment, the feedback solution may include per TP PMI, per TP RI, and per TP CQI feedback for all TPs in the COMP set and joint CQI feedback for partial TPs in the set of COMPs. This embodiment is similar to the second and third embodiments except that the UE can indicate to the eNB that some of the TPs in the COMP set may not be suitable for joint transmission and are excluded from the CQI calculation for joint transmission . One of the following methods may be used: a state of rank = 0, for example, corresponding to the absence of transmission, using the per TP CQI = 0 already specified in the specification, is stored in the rank index table And / or all zero entries into each of the codebooks, and when such a situation occurs, in the per RP RI corresponding to rank = 0 and / or in the codebook corresponding to rank = 0 And feeds back the per TP PMI corresponding to all zero entries.

In another embodiment, the feedback solution may include independent per TP sub-band PMI, RI and / or CQI feedback. These CSI parameters are calculated assuming a single-point transmission from the corresponding TP on the corresponding sub-band. The UE may feed back the PMI / RI / CQI for a subset of subbands, where the subset may be the same or different for each TP. Some examples of subsets selection methods include the following: The CSI of a TP that provides the greatest throughput for each sub-band is reported, and for each TP a specific number of CSIs of sub- Is reported. These sub-bands may include those with sufficiently good channel conditions or simply the best M sub-bands, where M is pre-defined and known for both the transmitter and the receiver.

An apparatus and method are provided for transmission schemes for utilizing feedback solutions that work together with CoMP transmissions.

가 곱해질 수 있고, 여기에서

는 UE로부터 피드백된 또는 달리 제로로서 셋팅된 페이즈 값이다. 만약 TP로부터의 채널의 랭크가 UE로 송신된 데이터 레이어들의 전체 수 보다 작다면, 데이터 레이어들의 서브세트가 TP에 의해서 송신된다. 서브세트는 TP를 제어하는 eNB 및 UE 모두가 알고 있는 것으로 가정된다. 레이어 인덱스들은 RRC 또는 PDCCH를 통해서 UE로 시그널링될 수 있다. More specifically, in one embodiment, transmission schemes for enabling a feedback solution can provide joint transmissions from the plurality of TPs having the same codewords across the same sub-bands. In this embodiment, the TPs transmit the same data layers to the UE on the same time / frequency resources. Each data layer is precoded in each TP using a precoding vector that is part of the precoding matrix corresponding to the fed back PMI from the UE. On TP _i, on each data layer (k)

Can be multiplied, where < RTI ID = 0.0 >

Is the phase value fed back from the UE or otherwise set to zero. If the rank of the channel from the TP is less than the total number of data layers sent to the UE, then a subset of data layers is transmitted by the TP. The subset is assumed to be known by both the eNB and the UE controlling the TP. The layer indexes may be signaled to the UE via the RRC or PDCCH.

In another embodiment, a transmission scheme for feedback solutions can provide joint transmissions from multiple TPs with different codewords across the same sub-bands. In this embodiment, different data layers may be transmitted from different TPs on the same time / frequency resources and to the same UE. The data layers transmitted from one TP may be associated with codewords transmitted on different TPs, i.e., codewords different from TP-specific codewords. Thus, more than two codewords may be transmitted on the same radio carrier to the same UE. Additionally, TP may be allocated with rank = 0 transmission, i. E. No data transmission from TP. This payout is signaled to the UE.

In another embodiment, a transmission scheme for enabling feedback solutions may provide transmit diversity over TPs. In this embodiment, when two TPs are associated with a UE in a joint data transmission, such two TPs are precoded into their corresponding precoding matrix indicated by the fed back PMI, followed by two or four virtual antenna ports Can be regarded as. In the case of Rank 1 transmission, a single codeword is encoded by Alamouti (e.g., Space-Frequency Block Coding (SFBC)) coding to generate two layers, Each layer is transmitted from one TP after separate precoding at each TP. In the case of a Rank 2 transmission with two codewords, each codeword is encoded by Alamouti (SFBC) coding to generate two layers, and each layer is separated by a separate precoding in each TP After roughing, it is transmitted from one TP. Instead, if each of the two TPs each have one or two antennas, then a Release 8 two-port or four-port Tx diversity scheme is used across two TPs without precoding. In this alternative, UE specific reference signal (DM-RS) ports as specified in TP specific RS ports or as defined in releases 9 and 10 are reused for channel estimation for demodulation.

In another embodiment, a transmission scheme for enabling feedback solutions may provide open-loop spatial multiplexed CoMP transmission. In this embodiment, an open-loop transmission is applied across the antenna ports of a plurality of TPs. Each TP transmits the same or a different data stream and no PMI feedback is required. When each TP has more than one antenna port, open-loop precoding is performed at each TP. Precoding vectors or matrices in each TP are predefined and PMI feedback is therefore not required. In this embodiment, the DM-RS may be used for data transmission, and UEs need not know precoding vectors or matrices.

In another embodiment, a transmission scheme for utilizing feedback solutions may provide joint data transmission from multiple TPs over different sub-bands. In this embodiment, joint data transmission is performed on separate (non-overlapping) sub-bands from multiple TPs with at least one of the following choices: different TPs split into a single MCS across separate sub-bands Different TPs may be used to transmit different segments of the codewords on the sub-bands, or different TPs may be used separately to achieve different MCS across separate sub-bands, using the output of the same channel forward error correction encoder, Applying the matching and then applying the channel coding on such TB with each TP sending its portion of the codeword on a sub-band separated from the other TPs, or each TP having a separate TB, and then applying different TPs Are transmitted on separate sub-bands.

Also provided is an apparatus and method for configuring feedback and transmission schemes that work together with CoMP transmissions.

More specifically, in one embodiment, configuring feedback and transmission schemes that work together with CoMP transmissions provides a configuration of feedback modes of operation. In particular embodiments, the solutions for configuring the feedback report mode for closed loop CoMP transmission may include a common rank (i.e., one rank for all TPs) or a separate rank (for each TP) The separate ranks may be jointly coded and may be fed back together in the same rank report RI). In certain embodiments, for each TP, separate CQI / PMI reports as specified in Release 8 through Release 10 are fed back to the eNB, and the CQI feedback in such reports assumes a single TP transmission, Derived in the same manner as specified in the releases. In certain embodiments, CQI / PMI reports for each TP are sent on the PUCCH or PUSCH. If transmitted on the PUCCH (e.g., as a periodic report), different reports for different TPs are transmitted in different subframes in a Time Division Multiplexed (TDM) manner. If sent as a PUSCH (e.g., as an aperiodic report), all reports for the different TPs are multiplexed together. In certain embodiments, in addition to the reports, CQI reports are configured that feed jointly derived CQIs for each codeword assuming that identical layers of data are transmitted from each TP. Such reports are transmitted on the PUCCH as periodic reports and multiplexed with other CQI / PMI reports in TDM manner or multiplexed with other CQI / PMI reports and transmitted on the PUSCH as aperiodic reports.

More specifically, solutions for configuring the feedback mode for closed loop CoMP transmission include Release 8 feedback modes 1-1 and 2-1 for the PUCCH, and modes 3-1, 1-2 and 2- 2 on the PUCCH and / or PUSCH for closed-loop transmission. In these modes, for each TP, feedback reports of the same types as specified in Release 8 are used. Additionally, joint CQI reports are derived and fed back. In certain embodiments, for a selected sub-band report, the selection of the highest-M sub-bands is based on the joint CQI from multiple TPs rather than the individual CQI for each TP. In these embodiments, the UE derives and feeds back separate CQI / PMI reports for each TP based on the selected sub-bands, and assumes a separate transmission from each TP. In a particular embodiment of these embodiments, the UE may additionally derive and feedback joint CQIs for each selected sub-band by assuming a joint transmission from all participating TPs.

In another embodiment, configuring feedback and transmission schemes that work together with CoMP transmissions provides a configuration of the transmission modes of operation. In certain embodiments, a solution for configuring a transmission mode for CoMP transmission comprises configuring a closed-loop spatial multiplexed CoMP transmission mode. Transmission mode supports separate CQI / PMI reports for each TP. In addition, joint CQI feedback is constructed. Dynamic switching between CoMP and non-CoMP transmission is supported by this mode of operation. In certain embodiments, an open-loop spatial multiplexed CoMP transmission mode is configured that does not require PMI feedback from the UE. In this embodiment, optionally, pre-defined or eNB determined precoding vectors are applied in TPs. In certain embodiments, constructing closed-loop and open-loop spatial multiplexed CoMP transmissions is included in one transmission mode (i.e., spatially multiplexed CoMP transmission mode). It is made transparent to the UE whether any transmission (i.e., closed-loop or open-loop) is valid. The UE need only be configured with different feedback modes to achieve switching between them. For example, if the UE is configured with CQI-only (no PMI) feedback, open-loop transmission is used, whereas if the UE is configured with PMI / CQI feedback, closed-loop transmission is used. In certain embodiments, transmit diversity with or without precoding is configured for two TPs. To generate pairs of coded symbols to be transmitted from each TP, Alamouti types of encoding are applied. The CQI calculation at the UE for feedback assumes that Alamouti coding is used.

Also provided is an apparatus and method for a CSI-RS solution that works with CoMP transmissions. This solution considers a method of CSI-RS multiplexing in a cell with multiple low power nodes (LPNs) and a macro-eNB sharing the same cell ID. Two CSI-RS configurations may be used, one for macro-eNB and one for all LPNs. Each LPN transmits a CSI-RS across different sub-bands and the bandwidth of the system bandwidth or operation is covered by the CSI-RS from all the LPNs. The sub-band to which the CSI-RS is sent for each LPN hop across the entire system bandwidth over time. The hopping pattern of the CRS-RS for each LPN may follow the same cycle but may have different sub-band offsets. The CSI-RS for the macro-eNB is transmitted over the entire system bandwidth independently.

Reference will now be made, by way of example, to the accompanying drawings, illustrating various exemplary embodiments of the present disclosure. Although various details are set forth in the following description, it is to be understood that the disclosure is not intended to limit the scope of the invention to those skilled in the art, which may be practiced without these specific details, It will be appreciated that numerous implementation-specific decisions may be made to the invention described herein, in order to achieve particular goals of the inventors, such as compliance with the constraints. While such a development effort may be complex or time-consuming, it will nevertheless be routinely achievable by those skilled in the art having the benefit of this disclosure. For example, in order to avoid limiting or obscuring the disclosure herein, selected aspects are shown in block diagram form and in flowchart form, instead of the specific description. In addition, some portions of the specific descriptions provided herein are presented in connection with algorithms or operations on data in a computer memory. Such descriptions and representations are used by those skilled in the art to explain and convey the substance of such work to others skilled in the art.

In a network of LTE standards, CSI reference signals (CSI-RS) may be transmitted within specific subframes as a reference signal. It is desirable to enable effective transmission schemes assuming that the channel state information-reference signal (CSI-RS) is designed such that the UE can individually measure the channel of the macro-eNB and each remote radio head (RRH) . In such transmission schemes, it is desirable to avoid excessive feedback overhead. Also, in order to minimize the impact on the system and the UE, it may be helpful to reuse as many of the elements or structures of existing feedback mechanisms as possible. For example, a precoding matrix indicator (PMI) (which is used by the UE to feed its desired precoding vector or matrix back to the eNB) may be defined as being selected from existing codebooks. It is therefore desirable to provide a feedback mechanism that works in conjunction with CoMP transmission methods.

In addition, the performance of the CoMP operation is highly dependent on the transmission scheme. It is therefore important to cooperate with signal processing at different transmission points (TPs) to form an effective transmission that can take advantage of CoMP. This cooperation may be in the form of cooperative non-beamforming (CB) and / or cooperative scheduling (CS), where each UE may receive data only from a single TP at a time; In order to minimize or avoid interference caused to other UEs, PMI and / or time / frequency resources are cooperated between the nodes in the CoMP set. An alternative cooperative method can be realized through joint transmission (JT), wherein the UE simultaneously receives data from multiple TPs.

In Release 10 of 3GPP resources, CSI-RS was introduced for UE to measure CSI for downlink transmission. As the number of transmit antennas involved in multiple-input and multiple-output (MIMO) transmissions is increased, the signaling of CSI-RS overheads from the eNB to the UE is increased. In order to control this overhead signaling and also to support up to 8-tx transmission, the CSI-RS is not transmitted in all subframes so that the CSI-RS transmits a Rel-8 common (or cell-specific) Sparse < / RTI > in the time domain as compared to the time domain. In Release 10, it is required that each UE measure and report CSI based on a single CSI-RS configuration. In Release 11 of the 3GPP study study phase of CoMP scenario 4, all low power nodes (LPNs) such as the macro eNB itself and the RRHs in the macro-cell coverage area share the same cell ID. In this case, the UE will not be notified directly of the presence of RRHs, but only with the CSI-RS ports associated with each RRH. Since the number of RRHs in a cell may be relatively large, it is desirable that the CSI-RS design and configuration is simple and resilient. Also, for backwards compatibility purposes, it is desirable that the CSI-RS design and configuration be transparent to Release 10 type UEs. It is also desirable that the increase in complexity at the UE is kept low.

In a system that takes CoMP operation, a set of transmit / receive nodes cooperating to service one or a plurality of UEs forms a CoMP set. The nodes in the CoMP set may be low power nodes (LPNs) and / or eNBs, such as remote radio heads (RRHs). LPNs may include, but are not limited to, microcells, picocells, femtocells, and the like.

Figure 1 shows an example of a CoMP arrangement with one macro-eNB and six RRHs, where macro-eNB is located at the center of the cell while six RRHs are located at the cell edge. It is assumed that the nodes in the CoMP set are connected via a backhaul, for example, by optical fibers.

Collaborative nodes may transmit and receive digitized baseband signals or radio frequency (RF) signals over backhaul connections. In some implementations, instead of point-to-point connections between all nodes, nodes may all be connected to a single central entity. This central entity may be, for example, an eNB or a central processing unit. For illustrative purposes, the backlogged connections are characterized by zero latency and infinite capacity. In order to simplify the description, the RRH or macro-eNB is also referred to as a transmission point (TP).

Four different deployment scenarios were defined for the CoMP study. These four scenarios are categorized into homogeneous and heterogeneous batches. More specifically, in the case of homogeneous batches, the first scenario describes a homogeneous network with intra-site CoMP and the second scenario describes a homogeneous network with high Tx power RRHs (inter-site CoMP) Describe a network. In the case of heterogeneous batches, the third scenario describes a heterogeneous network with low power RRHs in macrocell coverage, where the transmit / receive points generated by RRHs have cell IDs that are different from macrocells. The fourth scenario describes a heterogeneous network with low power RRHs within macro cell coverage where the transmit / receive points generated by RRHs have the same cell IDs as the macrocell.

In a homogeneous network deployment, macro-cells are typically formed by uniformly placing eNBs within a geographic area. Each of the cells has the same or similar transmit power and is thereby serviced by an eNB having the same or similar size. An example is shown in FIG. 2, where a total of 21 cells are arranged with six cell sites. Each site contains three eNBs, one for each cell. Cell towers are normally disposed within each site and high transmission power is typically used to provide a large coverage area.

While in a homogeneous arrangement, low power nodes are placed through the macro-cell layout. An example is shown in Figure 1, where RRHs can be low power nodes.

The embodiments described herein apply to all four of these scenarios, unless otherwise specified. Further, while the described embodiments are based on LTE systems, such concepts may be equally applicable to other wireless systems.

In order to enable coherent reception of downlink data signals and to assist measurements that may be used to enable modulation and coding rate allocation, systems such as LTE systems, in addition to data signals , and uses the reference signals (RS) transmitted by the eNB. In MIMO systems, different RSs may be transmitted from different transmit antennas. Receivers in a system (e.g., a UE) typically process the received RS to determine channel state information (CSI) for a given instant. CSI may be obtained for multiple transmit / receive antenna pairs (i. E., Individual channels collectively constituting a MIMO channel). The CSI information obtained by the receiver may be used to enable or improve the reception of downlink data signals.

Different types of RS are defined within the LTE system. More specifically, cell-specific (common) reference signals (CRS) are transmitted regularly through the cell and become available RSs for all UEs. The CRS is not precoded, so if a precoded data signal is transmitted to the UE, it is necessary to form an estimate of the composite (precoded) channel over which the data signal has passed (which is necessary to precisely demodulate the data signal) , The UE receiver needs knowledge about both the CSI (obtained from the non-precoded CRS) and the precoding vector or matrix that was employed in the eNB. This is generally referred to as codebook-based precoding because the selected precoding vector or matrix is typically one from a pre-defined set of precoding vectors or matrices (codebook). Antenna ports 0 through 3 use CRS in the LTE system. In addition, UE-specific reference signals (DRS) are RSs embedded with data intended for a particular recipient UE. The DRS is generally precoded using the same precoding vector or matrix, as applied to the data signal (precoding is typically arranged to optimize the quality of reception at the intended UE). Accordingly, the UE receiver does not require acknowledgment of the applied precoding vector or matrix at the transmitter - rather, the UE receiver simply decides from the DRS the complex CSI (including the effects of both precoding and propagation channels) RTI ID = 0.0 > CSI < / RTI > Antenna ports 5, and 7-14 use DRS in LTE systems.

In addition, CSI reference signals (CSI-RS) are RSs transmitted in certain pre-configured subframes and RS intended for all Rel-10 UEs in the cell. The CSI-RS is used for CSI estimation only for Rel-10 and not for data demodulation at the UE, and is not transmitted in all subframes, and multiple configuration options are available, Similar to CRS, except that the configuration of the CSI-RS in the cell is independent of the cell ID.

An example of a transmission scheme using CSI-RS is shown in FIG. This figure shows a simplified block diagram of eNB-UE processes for dynamic DL data scheduling and transmission in LTE-A (Rel-10) using Transmission Mode 9 (TM 9). In LTE, 9 DL transmission modes are defined, and each mode can be used for multiple antenna transmissions with multiple antenna transmissions, open-loop or closed-loop MIMO, Supports specific transmission schemes. A full list of DL transmission modes in LTE is shown in Table 1 below. TM1 to TM7 are specified in Rel-8. TM8 was introduced in Rel-9 to support DL dual layer beamforming, and TM9 was introduced in Rel-10 to support up to 8 layers of MIMO transmission with up to 8 transmit antennas.

Transmission mode Supported DL Transmission Systems Rel-8 Rel-9 Rel-10 RS for DL CSI measurement RS for PDSCH demodulation Mode 1 Single antenna, port 0 Yes Yes Yes CRS








CRS








Mode 2 Transmit diversity Yes Yes Yes Mode 3 Open-Loop MIMO Yes Yes Yes Transmit diversity Yes Yes Yes Mode 4
Closed-loop MIMO Yes Yes Yes Transmit diversity Yes Yes Yes Mode 5 MU-MIMO Yes Yes Yes Transmit diversity Yes Yes Yes Mode 6 Closed-loop MIMO with a single transmit layer Yes Yes Yes Transmit diversity Yes Yes Yes Mode 7 Single Layer Beam Forming Yes Yes Yes CRS DRS Transmit diversity or single antenna port Yes Yes Yes CRS CRS Mode 8 Dual Layer Beam Forming Yes Yes CRS DRS Transmit diversity or single antenna port Yes Yes CRS CRS Mode 9 Up to 8 layer closed-loop MIMO transmissions Yes CSI-RS DRS Transmit diversity or single antenna port transmission Yes CSI-RS CRS

DL transmission modes and supported DL transmission schemes for UE-specific PDSCH data dynamically scheduled in LTE

As shown in FIG. 3, a plurality of steps may be performed by the eNB and the UE. More specifically, a CSI-RS configuration step 310 is performed. In Release 10, a set of RSs, i.e. CSI-RS symbols, are defined. The CSI-RS is used, if necessary, for channel measurements and to derive feedback on the quality and spatial properties of the channel (s). It is predicted that CSI-RS will be the main reference signals used for CoMP operation in subsequent releases of LTE. Feedback derived by the UE from the CSI-RS can be used for different transmission schemes such as single-cell single- and multi-user MIMO as well as cooperative multi-cell transmission.

The configuration of the CSI-RS is cell specific and includes parameters defining the pattern, periodicity, subframe offset, and number of CSI-RS ports. The CSI-RS pattern employs a base pattern having length-2 time domain orthogonal cover codes (OCC) for each pair of antenna ports. The patterns have a nested structure where the pattern used for a small number of CSI-RS ports is a subset of the pattern used for a large number of CSI-RS ports. To provide pattern reuse factor variation across cells or TPs, multiple patterns / configurations can be used for the network. The configuration parameters of the CSI-RS are explicitly signaled through higher layers (via radio resource control-RRC-signaling) within each cell. An example of a CSI-RS configuration for a normal cyclic prefix (CP) duration is shown in FIG.

Next, a channel estimation step 312 is performed. Based on the received signal for CSI-RS resources, the UE estimates the DL channel on the corresponding resource elements.

Next, the CSI calculation step 314 is performed. For efficient data transmission, the UE measures channel state information (CSI) and reports to the eNB. The CSI feedback may include parameters such as a channel quality indicator (CQI), a precoding matrix indicator (PMI), a precoding type indicator (PTI), and a rank indicator (RI). Depending on the feedback mode, all or some of these parameters are included in the CSI feedback.

The CSI feedback may be wideband or sub-band. In the wideband CSI feedback, a single value of each CSI parameter is calculated and reported for the total bandwidth. In sub-band CSI, the total bandwidth of the carrier is divided into sub-bands (having a configurable size) and a set of CSI parameters is calculated for each sub-band and reported to the eNB.

The CSI feedback parameters derived by the UE may form part of the uplink control information (UCI) transmitted by the UE on a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH).

Next, a scheduler step 316 and a DL grant step 318 are performed. The scheduler determines what time / frequency resources of the physical downlink shared channel (PDSCH) are allocated for DL transmissions to the UE. Time / frequency resources are represented in terms of allocated resource blocks (RS), where one RB contains 12 sub-carriers of frequency resources during one 0.5 ms time resource slot. This payout information, which together with the other transmission parameters form DL acknowledgment, is transmitted, at step 320, to the UE as downlink control information (DCI) on the physical downlink control channel (PDCCH). This information is detected and recorded by the UE and used for the detection of data transmitted on the PDSCH in step 322. [

Next, a transfer block processing step 324 is performed. Data arrives from the higher layer in the form of transport blocks (TBs). In current releases of LTE, the maximum of two TBs is transmitted in each transmission time interval (TTI). Each TB is encoded into a codeword in several steps as shown in FIG. First, a cyclic redundancy check field (CRC) is attached to the TB. If the size of the TB is greater than a certain value, code block segmentation is applied to divide the TB into smaller blocks referred to as code blocks. Channel coding is applied independently on each code block. Rate matching is applied based on the modulation and coding scheme (MCS) allocated to the UE. Finally, rate-matched coded bits are concatenated to form a codeword.

Next, a physical channel processing step 326 is performed. The codeword formed by the coding unit is transformed into OFDM symbols to be transmitted on the DL channel. Figure 6 shows the steps involved in this process. Each codeword is first scrambled by a cell-specific scrambling sequence. The scrambled bits are then modulated to form modulation symbols. Modulation symbols from all codewords are mapped to the layers, where the number of layers (or transmission rank) is indicated within the DL acknowledgment carried in the PDCCH. Subsequently, precoding is applied to the data layers to form signals for each antenna port. The output of the precoder is mapped to the resource elements in the frequency domain and then an OFDM signal in the time domain is generated and transmitted across each antenna port. The resource element RE is the minimum unit of time / frequency resource defined in the LTE system as one sub-carrier of one OFDM symbol duration and frequency of time.

The block diagram of FIG. 3 illustrates the procedures for downlink data transmission in non-CoMP transmission. In the case of CoMP transmissions, some of these procedural components may need to be modified to take full advantage of the possibilities of cooperative communications.

There are a plurality of feedback and transmission methods for multi-point operation. One such method feeds back the joint CSI. In this way, multiple TPs are considered together as a virtual single TP. When Hi expresses the channel matrix from TPi to UE, the composite channel from this virtual single TP to UE is:

Based on H _c , one set of CSIs (e.g., PMI, CQI, and RI) is calculated and fed back to the eNB. This scenario is suitable for joint transmission (JT) of the same data from all cooperating TPs. An advantage of this method is that the same feedback modes can be reused as used in current / legacy systems, and the advantages of multipoint transmission can still be exploited.

One problem with this feedback method is that existing codebooks are designed only for up to 8 antenna ports so that if the total number of antenna ports from all TPs included in JT is greater than 8, . Another problem is that the transmit power of the multiple TPs and consequently the signal strengths received from them at the UE side may not be the same, while the known codebooks are designed assuming the same power level for all antenna ports will be. Thus, the known codebooks may not be efficient for use in joint transmissions in heterogeneous networks where the transmit powers from each TP may not be the same, and hence a new design may be required. Another problem is that known codebooks are often designed, assuming that all antennas are co-located on the same TP and are therefore close to one another; In antennas more distributed over different TPs, the codebook may need to be modified to accommodate different antenna correlations.

Other methods feed back separate rank-1 PMI, common CQI, and inter-TP phase information. This method feeds back separate rank-1 PMIs for each TP and allows TPs to transmit the same data using their own PMI (and using a common CQI). In this way, each TP can individually apply non-formatting to the data it transmits; Due to uncontrolled phase differences between the TPs, the signals from the different TPs will be able to be summed with random phases, thereby limiting the overall beam forming gain. One solution to this problem is to feed back some phase information for the channels from each of the TPs and to use such information in the TPs during non -forming operations in an attempt to achieve constructive phase alignment at the UE, To help achieve higher overall beam forming gains.

In certain known methods, this phase feedback method for rank-1 transmission is used with two TPs. When the PMI for each TP is obtained from its channel matrix and the phase difference [theta] is calculated so that the transmission phase in PT # 2 is compensated by this value, the received signals from both TPs are transmitted to the UE side In a coherent manner. In a mathematical representation, this transmission method is described as follows:

Where y ₁₁ and h ₂₁ denote the channel matrices and UE between TPs 1 and 2, respectively, and w ₁ and w ₂ denote the received signal vectors at TPs 1 and 2 Respectively, and n is a vector of additional thermal noise at the UE ' s receiver.

In other solutions as opposed to individual (per-TP) PMI calculations, the PMI calculation is performed jointly. In this joint calculation approach, it is assumed that the PMIs are sub-vectors of a single precoding vector computed on the basis of the complex channel (H _c ). In other words, if we denote the right singular vector of H _c by v, then v is quantized as:

Where Q (.) Denotes the quantization operation; _{p i (i = 1, 2} , ..., n) is free _{m i xl (m i = 1} , 2, 4, 8) for TPi selected from the codebook for the _i m antenna port coding vector, and m _i is the number of Tx antennas at TP i; and α _i and θ _i are the channel amplitude and phase values associated with TP i. With additional amplitude information and also joint calculations of PMIs, more gain is expected in this approach when preparing for individual PMI calculation methods.

However, one problem with the methods described above is that it is not clear how, during both works for the Rank-1 transmission, how to feed phase information for one or more transmission ranks. Also, in the first method, if the number of receive antennas is greater than one, it is impossible to select the phase value [theta] so that the received signals constructively sum over all receive antennas.

The other method feeds back independent TP TPIs, RIs, and CQIs that are jointly calculated. In this way, the UE feeds back the PMI, RI and CQI for each TP, and each TP sends different data streams to the UE. The transmission can be described as follows:

Here, y denotes the received signal vector at the receive antennas of the UE, respectively, H _i denotes a channel matrix between the i reception of the transmit antennas of the first TP with the UE antenna, W _i is applied from the i-th TP Where x _i is the data symbol transmitted from the i th TP and n is the vector of the additional thermal noise at each receive antenna.

In this way, different data streams are sent from different TPs and joint optimization is applied to select the per TP TPMs, RI, and CQIs for all TPs, thereby allowing for the total data throughput Maximize.

Other methods provide CSI-RS design. From the LTE Release 10 onwards, in order to measure and feed back DL channel status information (CSI) from a single serving cell (i.e., the cell used for downlink transmission to the UE), the cell specific CSI- . A Rel-10 UE may be composed of multiple sets of CSI-RS configurations, one for the serving cell and the other for the other neighboring cells. While the CSI-RS configuration for a serving cell is typically shown as a non-zero transmit power CSI-RS configuration, CSI-RS configurations for other cells are denoted as CSI-RS with zero transmit power, (I.e., the resource elements associated with some CSI-RSs may be empty (e.g., by the serving cell) to assist the UE in receiving improved reception of the CSI-RS from other cells on the corresponding RE . In Rel-10, the UE only measures and feeds the DL CSI based on the non-zero transmit power CSI-RS.

When RRHs are placed in a cell covered by a macro-eNB, and when RRHs share the same cell ID as a macro-eNB, several options for CSI-RS configuration are considered. In one scenario, the antennas of the RRHs may be considered as part of the macro-eNB and thus a single CSI-RS configuration may be used, where one CSI-RS port is allocated for each of the antenna ports. For example, assuming that one macro-eNB and three RRHs are located in a cell sharing the same cell ID and each has two antenna ports, the 8-port CSI-RS configuration specified in Rel-10 Where one CSI-RS is allocated for each of the antenna ports. As shown in FIG. 7, a Rel-10 CSI-RS configuration # 0 having eight CSI-RS ports can be used.

However, this configuration does not work when the total number of antenna ports (macro-eNB + RRHs) exceeds 8 because the maximum number of antenna ports supported by Rel-10 is 8.

An alternative option is to have a separate CSI-RS configuration for each TP. An example is shown in Fig. For each UE, the eNB can configure each UE with UE specific CSI-RS configuration (s) for channel estimation and CSI feedback, since CSI-RS configurations are signaled in Rel-10 in a UE specific manner . A UE sufficiently close to the TP may be typically configured with a CSI-RS allocated for that TP. Accordingly, different UEs will be able to measure on different CSI-RS resources, depending on the locations of the UEs within the coverage area spanned by multiple TPs sharing the same cell ID. However, it should be noted that in Rel-10, the UE only measures and reports a single CSI-RS configuration with non-zero transmission power. In order to enable the UE to measure and report channel feedback for multiple TPs, some changes beyond Rel-10 are required to enable CSI feedback for multiple TPs. In this case, a large number of configurations may be needed to support a large number of TPs in the cell. In addition, the eNB needs to know which TPs cover the UE in order to allocate the corresponding CSI-RS configurations for the UE. When the UE moves from the coverage area of one TP to the coverage area of another TP, a CSI-RS reconfiguration for the UE may be required if the CSI-RS of the new TP is not yet configured for that UE.

Thus, in one embodiment, the feedback method includes feedback on the per-TP channel quality indicator (CQI) feedback as well as the per-transmit point (TP) precoding matrix indicator (PMI), per TP rank indicator (RI), and joint CQI feedback Can be provided.

In this way, the UE feeds back the PMI, RI and one or more CQI (s) for each associated TP. PMI and RI are computed assuming joint data from multiple TPs (as described below) or calculated separately for each TP, assuming a non-joint transmission, while CQIs or CQIs are calculated as the feedback PMI And RI are used to calculate the data transmission from the corresponding TP only. Also, depending on whether the number of codewords is 1 or 2, respectively, one or two joint CQI (s) are also fed back. This feedback scheme is used for per TP data transmission to the UE or for joint transmission of the same layers of data from multiple TPs.

In the case of joint data transmission, in the case of joint data transmission, if the transmission ranks of all TPs are equal, that is to say equal to R, then all TPs transmit the same data vector x with length R. If the transmission ranks of the various TPs are different, TP i selects R _i data layers from x and transmits these sub-vectors, where R _i is the number of layers supported by TP i. An example of such a mixed-rank transmission is shown in FIG. In Figure 9, the four layers of data are intended to be transmitted using three TPs. TP # 1 has four antenna ports, and TPs # 2 and # 3 each have two antenna ports. In this example, precoding at TP # 1 is applied to all data layers x ₁ , x ₂ , x ₃ , x ₄ , while precoding at TP # 2 is applied only to x ₁ , x ₂ , And the precoding in TP # 3 applies only to x ₃ , x ₄ .

이다. UE에서의 보다 정확한 CQI 추정들을 위해서, UE는 모든 TPs에 의해서 이용되는 인덱스 세트들을 알아야 한다. 여러 실시예들에서, UE 및 TPs가 동일한 S_i를 이용하도록 보장하기 위해서, 복수의 접근방식들이 이용된다. The index set S _i is defined to denote the index of the layers precoded and transmitted by TP i,

to be. For more accurate CQI estimates at the UE, the UE must know the set of indexes used by all TPs. In various embodiments, multiple approaches are used to ensure that the UE and TPs use the same S _i .

More specifically, in one approach, pre-defined rules are used. In this approach, index sets are determined from rank indices (known by the eNB and the UE via signaling) and are based on a pre-defined rule agreement between the eNB and the UE. For example, a rule may be that each TP i with a rank index R _i selects S _i = {1, ..., R}. Another example is to set the rules so that the layers are distributed as uniformly on the TPs as possible. For example, in FIG. 9, a payout is made so that each data layer is correctly transmitted from two TPs.

Such a rule may be specified as a standard or may be selected from several pre-defined sets and signaled semi-statically. Also, a rule may be based on some known cell attribute (e.g., cell ID) or CoMP set index. In these approaches, dynamic signaling of S _i is unnecessary and does not result in overhead (e.g., on the downlink or uplink control channel).

In another approach, explicit signaling of S _i is used. In this approach, the index sets are determined by the eNB and signaled dynamically (e.g., as part of the DCI on the PDCCH) or semi-statically (e.g., via RRC signaling) for the UE. The selection of the eNB of S _i s may be based on the feedback received from the CQIs and other uplink control information (UCI) or UE. This approach gives some overhead on the downlink control channel.

In another approach, reporting S _i on UCI and DCI is used. In this approach, index sets are determined by the UE and reported to the eNB as part of the UCI. Similar to other CSIs, the eNB uses the UCI received from the UE to determine the set of indices to use. This final decision is signaled to the UE on the PDCCH as part of the DCI. This approach gives some signaling overhead (e.g., on the uplink control channel and downlink control channel). For signaling S _i , one exemplary approach is to specify a bitmap with length R _i , where '1' indicates that the corresponding layer should be used for transmission, and ' 0 'indicates that the corresponding layer is not to be scheduled for transmission.

In general, this type of joint transmission can be described as in Equation (1) below.

Here, x (S _i ) represents the elements of the data vector x having the indices of the set S _i . H _i is the channel matrix for the UE from TP. W _i is the precoding matrix or vector used by TP i, and n is additive white Gaussian noise.

More specifically, in particular embodiments, the UE feeds back the per-TP PMI and RI assuming joint or non-joint transmission, and sends back the CQI (s) for each TP assuming non-joint transmission do. Also, one joint CQI for each codeword is fed back, where the total number of codewords is determined by the maximum number of data layers over all TPs.

In the case of a joint transmission, the layers used in each TP are recognized by both the eNB and the UE for better matching between the feedback PMI / RICQI from the UE and the actual channel used for data transmission, Help the calculation. The layers used in the TP are indicated by the index set, S _i . Each index set S _i includes an index of the data layers to transmit from TP i. Accordingly, the network and the UE have a common understanding of S _i for each TP.

The rules for how to derive S _i from RIs may be specified. Or some pre-defined set of indices may be specified and signaled to the UE semi-statically for each TP. S _i may be signaled from the eNB to the UE (e.g., via RRC signaling or on the downlink control channel). The desired value of S _i will be derived at the UE and can be signaled on the uplink control channel from the UE to the eNB. Based on the proposed S _i and other UCIs received from the UE, the eNB derives S _i to be used by TP i and signals that S _i to the UE on the PDCCH as part of the DCI.

The calculation of precoding matrices W _i and layer indices S _i for each TP i can be performed jointly or independently (as in a single cell paradigm).

In certain embodiments, when performing a joint PMI / RI calculation, the UE jointly determines PMI / RI for all TPs based on all channel matrices. Based on deployment and application scenarios and different performance optimization criteria, a plurality of approaches may be utilized.

In a first approach, joint PMI and rank selection are implemented based on maximizing throughput. In a slow mobility scenario, it may be required to maximize instantaneous link throughput. As an optimization criterion, in order to obtain the throughput, the above-described equation (1) can be rewritten as shown in equation (2): "

는 W_i 및 S_i 에 의존하는 프리코딩 매트릭스이고 그리고 모든 제로 매트릭스로 시작함으로써 그리고 S_i 에 의해서 인덱스된 컬럼들(columns)을 대응하는 W_i 의 컬럼들로 대체함으로써 획득된다. 따라서, 이론적인 링크 스루풋을 최대화하기 위해서 각각의 TP에 대해서 PMI/RI/S_i 를 선택하는 것이 이하와 같은 수학식(3)으로 공식화될 수 있다:From here,

It is obtained by replacing the pre-coding matrix and a column of the W _i corresponding to the columns (columns) by the index, by starting with all zero matrix, and S _i, which depends on the W _i and S _i. Therefore, to maximize the theoretical link throughput, choosing PMI / RI / S _i for each TP can be formulated as: < RTI ID = 0.0 >

는 수신기 노이즈 파워 더하기 (CoMP 세트 외부의 셀들로부터의)간섭을 나타낸다. 상기 최대화에서, R_i 를 위한 탐색 공간은 코드북으로 규정된 범위

내의 모든 값들을 포함하며, 여기에서 N은 UE에서의 수신 안테나들의 수이고, M_i 는 TP i에서의 송신 안테나들의 수이다. R_i = 인 경우는 W_i = 0 에 즉, 모든-제로 프리코딩 매트릭스에 대응한다. 또한, 주어진 R_i>0에 대해서, W_i 에 대한 탐색 공간은 랭크 R_i 및 M_i 안테나 포트들에 대해서 규정된 코드워드이다. 또한, S_i 에 대한 탐색 공간은 크기 R_i 의

의 모든 서브세트들이다. Where P _i represents the transmit power from TP i, and

(From the cells outside the CoMP set). In this maximization, the search space for R _i is defined as the range defined by the codebook

Where N is the number of receive antennas at the UE and M _i is the number of transmit antennas at TP i. R _i = ≪ / RTI > corresponds to W _i = 0, _i . E., An all-zero precoding matrix. Also, for a given R _i > 0, the search space for W _i is a codeword defined for the rank R _i and M _i antenna ports. In addition, the search space for S _i has a size R _i

≪ / RTI >

The inclusion of the all-zero precoding matrix also allows the UE to present to the eNB that it excludes certain TPs from the CoMP set if it finds that it is more advantageous for the eNB to work with a smaller number of TPs . For example, if there are two TPs in the CoMP set and the received signal from one TP is significantly lower than the other TP, it would be better to use one TP for transmission in that case.

The above-described method for jointly selecting PMI, RI and layer allocation can be used to increase throughput in a joint transmission scenario, where the PMI of each TP is selected from the existing codebook. However, this approach may lead to computational complexity in the UE. In order to reduce this complexity, search spaces may be constrained to smaller sets. One way to achieve this is to predefine the index sets S _i . Hence, the maximization in equation (3) will only be performed over PMI and RI.

Thus, in certain embodiments, the UE selects all the channels from the TPs and jointly determines the PMI, the rank, and the selected layers for each TP, thereby maximizing the overall throughput criterion. Such information may be fed back to the eNB.

Also, in certain embodiments, joint PMI and rank selection may be based on diversity maximization. More specifically, in a scenario where the reliability of transmission has priority over throughput, it may be required to increase the degree of transmit diversity. One approach for joint determination of PMIs to increase diversity is orthogonalization of equal channels from each TP. In this method embodiment, W _i is selected such that H _i W _i (i = 1, 2, ...) are mutually orthogonal, as follows.

이 바람직하고, 여기에서 N은 수신 안테나들의 수이고 그리고 R_i 는 TP i로부터 송신된 레이어들의 수이다. 동시에, 이론적 스루풋이 최대화되도록 W_is가 선택되어야 한다. 다시 말해서, 이러한 PMI 선택 방법에서, 직교 조건에서 이론적 스루풋을 최대화하도록 W_is가 선택된다. 이러한 방법에서, UE는 먼저 방향들 H_iW_i 의 각각에서 신호를 검출하고, 이어서 최대 비율 조합(MRC) 수신기를 이용하여 그들을 조합한다. 따라서, 다이버시티 이득이 달성될 수 있을 것이다. 이는 비임포밍 이득이 달성되는 스루풋 최대화 접근방식에 대비된다. In order for the above equation to have a solution,

Where N is the number of receive antennas and R _i is the number of layers transmitted from TP i. At the same time, W _i s should be chosen so that the theoretical throughput is maximized. In other words, in this PMI selection method, W _i s is selected to maximize the theoretical throughput in orthogonal conditions. In this way, the UE first detects the signals in each of the directions H _i W _i , and then combines them with a maximum ratio combination (MRC) receiver. Thus, a diversity gain can be achieved. This is in contrast to the throughput maximization approach in which the beamforming gain is achieved.

Thus, in certain embodiments, the UE jointly determines the PMI for each TP to measure all the channels from the TPs and maximize the orthogonality between equal channels from the set of TPs. Such information is fed back to the eNB.

Also, in certain embodiments, per TP PMI and RI calculations are performed. More specifically, the UE computes PMI and RI independently for each TP and in a manner similar to legacy single TP systems. In other words, in contrast to a solution in which each PMI / RI is determined by considering all channels together, in this embodiment, the PMI / RI of each TP is solely determined by the channel of the corresponding TP.

One advantage of this CSI calculation is that its computation is similar to the CSI computation in legacy systems and thus can be transparent to the UE.

Additionally, a transmission scheme based on this method utilizes the power resources of all TPs. However, in this approach, since the PMI / RI computation is performed independently for all TPs, the signals from all TPs are added together at UEs with random phases and no inter-TP beamforming gain is obtained.

If the index set S _i is derived based on predefined rules, then only a single cell PMI / RI needs to be fed back. For example, if S _i = {1, ..., R _i }, then the transmission can be described as:

In an alternative approach, if the signaling of S _i is possible on the uplink control channel, after the single cell PMI and RI induction, the index sets may be jointly derived. This operation can be implemented by considering a metric similar to equation (3) where W _i and R _i are fixed and maximization is performed only for S _i .

Thus, in certain embodiments, the UE computes and feeds PMI and rank separately for each TP, or, with a fixed rank configured by the eNB, the UE sets the PMI to a fixed rank for each TP separately ≪ / RTI > The eNB then transmits the same number of data streams or portions of streams from each TP.

Also, in certain embodiments, a CQI calculation is performed. More specifically, after obtaining the PMI and RI, the CQI is derived based on the knowledge of what kind of receiver is to be used and the calculation of the corresponding SNR on each data layer. For example, in the case of an MMSE receiver, the SNR on layer k is obtained in Equation (4) as follows:

는 UE에 의해서 관찰되는 균등한 채널이다. From here,

Is an equal channel observed by the UE.

가 수학식(4)에서 이용되어야 한다. For the calculation of the CQI of the i-th TP for the per-TP data transmission,

Should be used in Equation (4).

Alternatively, in another embodiment, the feedback method may include a feedback indicator (PMI), a rank indicator (RI), and a channel quality indicator (CQI) feedback for each TP as well as common CQI and phase differences .

As described above, for feedback of the separated PMIs / RIs, these parameters can be calculated individually or jointly. In the separation calculation method, the inter-TP diversity or non-beamforming gain may or may not be achieved. On the other hand, joint computation can provide inter-TP beamforming gain or diversity gain. However, since the precoding matrices are quantized, some of the potential gain can not be achieved. One solution is to extend the codebook to obtain finer granularity for the precoding matrices. However, this method may require the design of a new codebook which may not be desirable. Another approach is to re-use existing codebooks, and also feed back some extra channel-dependent information in order to better match the transmission to the channel conditions. More specifically, this additional information may include certain quantized phase values.

을 그 데이터 레이어 k에 부가할 수 있다. 혼합형 랭크 송신의 일반적인 경우를 고려하면, 송신이 이하와 같은 수학식(5)에서 기술될 수 있으며:In this embodiment, in order for the transmitters to form signals of the transmitters so that the signals of the transmitters are coherently combined in the receiver, the UE determines whether the eNB in the single cell ID is the reference TP ), Or on the basis of the cell ID (in a multi-cell ID scenario), based on the measured cell ID of the cell (s) of the cell (s). Also, without eNB and UE correspondence for a particular reference point, the phase values can be relative. As a result, TP i is phase corrected

Can be added to the data layer k. Considering the general case of mixed rank transmission, the transmission can be described in equation (5) as follows:

는 TP i에 대한 페이즈 교정 대각선 매트릭스(대각선 행렬)이고, R_i 는 TP i(i = 1, 2,..., n 및 k = 1, 2,..., R_i)로부터의 송신 랭크이고,

는 TP i로부터의 레이어 k에 대한 페이즈 교정이고,

는 프리코딩 매트릭스

의 k-번째 컬럼이고, 그리고

는 W_i 및 S_i 에 의존하고 그리고 모두-제로 매트릭스로 시작하고 그리고 S_i 에 의해서 인덱스된 컬럼들을 대응하는 W_i 의 대응하는 컬럼들로 대체함으로써 획득되는 프리코딩 매트릭스이다.

는

로부터 동일한 방식으로 획득된다. 만약 페이즈들이 기준 TP에 대해서 측정된다면, 기준 TP의 페이즈 매트릭스가 아이덴티티(identity) 매트릭스이다. 따라서, 만약 CoMP 세트의 크기가 N_c 라면, N_{c -1} 양자화된 페이즈 매트릭스들이 피드백된다. 만약, 예를 들어 CoMP 세트가 동적으로 변화될 때, 기준 TP가 규정되지 않는다면, 각각의 TP에 대해서 하나의 페이즈 매트릭스가 리포트되어야 한다. From here,

R _i is the phase calibration diagonal matrix (diagonal matrix) for TP i and R _i is the transmission rank from TP i (i = 1, 2, ..., n and k = 1, 2, ego,

Is the phase correction for layer k from TP i,

Lt; RTI ID = 0.0 >

Th column of < RTI ID = 0.0 >

Is a precoding matrix that depends on W _i and S _i and is obtained by replacing columns indexed by S _i with the corresponding columns of the corresponding W _i starting with the all-zero matrix and being indexed by S _i .

The

Lt; / RTI > If the phases are measured against a reference TP, then the phase matrix of the reference TP is an identity matrix. Thus, if the size of the CoMP set is N _c , the N _{c -1} quantized phase matrices are fed back. If, for example, the CoMP set is dynamically changed, then a phase matrix should be reported for each TP if the reference TP is not specified.

가 벡터 공간 내에 가능한 한 정렬되도록, 프리코딩 매트릭스들 W_i 이 선택된다. 결과적으로, 각각의 데이터 레이어의 수신된 신호 벡터들이 수신기에서 건설적으로 부가되도록, 페이즈 교정들

이 선택된다. 만약 스루풋 최대화가 선택 기준으로서 고려된다면, W_i, R_i, S_i 및

의 선택이 이하와 같은 수학식(6)에서 기술될 수 있으며:For each layer k,

Precoding matrices W _i are selected such that they are as aligned as possible in the vector space. As a result, the received signal vectors of each data layer are constructively added at the receiver,

Is selected. If throughput maximization is considered as a selection criterion, W _i , R _i , S _i and

May be described in equation (6) as follows: < RTI ID = 0.0 >

는 양자화된 페이즈 매트릭스들의 세트로부터 선택된다. From here,

Is selected from the set of quantized phase matrices.

의 조인트 계산 즉, 스루풋 최대화가 상이한 TPs에 대해서 분리된다. 또한, TP i, W_i 및

가 순차적으로 획득될 수 있다. 이를 확인하기 위해서, 단일 수신 안테나의 경우에, 스루풋 최대화가 다음과 같으며;If the number of receive antennas in the UE is 1, then the number of layers should be 1, then W _i s and

, I.e., the throughput maximization is separated for the different TPs. Also, TP i, W _i and

Can be obtained sequentially. To confirm this, in the case of a single receive antenna, the throughput maximization is as follows;

이 동일한 페이즈를 가지도록,

가 선택되어야 한다. Here, B refers to a codebook. Each term H _i W _i can be maximized individually from the other terms, that is, W _i Only H _i Lt; / RTI > Since W _i is selected from the codebook, H _i W _i with the highest W _i is generally a complex number, ie has both magnitude and phase. As a result, all complex numbers

To have this same phase,

Should be selected.

를 획득한 후에, 공통 CQI가 수학식(4)로부터 각각의 레이어 상의 SNR을 계산하는 것에 의해서 유도될 수 있으며, 여기에서

. 이다.W _i , R _i , S _i and

, A common CQI can be derived by calculating the SNR on each layer from Equation (4), where < RTI ID = 0.0 >

. to be.

Thus, in certain embodiments, in addition to the PMI / RI / CQI feedback, the UE will be able to feed back one phase value of the super TP data layer.

Instead, in another embodiment, the feedback method provides precoding matrix indicator (PMI) and channel quality indicator (CQI) feedback for each TP as well as common RI and CQI. More specifically, the PMI assuming joint transmission and the CQI (s) assuming non-joint transmission are fed back for each TP. However, common RI and common CQI per codewords for all TPs (both derived assuming joint transmissions) are fed back to the eNB. Due to the reduced RI feedback, this method has a relatively small feedback overhead compared to the method of providing per-TP. Using a common RI for multiple TPs also leads to more balanced transmissions across different layers. For the sake of brevity, a common RI can be selected based on the minimum rank that all TPs can support.

Because the RI is the same for all TPs, this feedback mechanism is well suited to support a combination of codebook-based precoding and transmit diversity schemes. More specifically, an Alamouti code can be applied to single layer data to generate two layers of coded data, one for each TP. The data in each TP is precoded using PMI feedback for the TP.

Thus, in certain embodiments, the UE measures all channels from the TPs and determines a common rank for joint transmissions from all TPs and determines, for each codeword, a separate rank for each TP and joint CQI, Calculate PMI and CQI. A common rank is obtained jointly by simply selecting the lowest rank among those derived for each of the plurality of separate channels from each TP. Such information is fed back to the eNB.

Instead, in another embodiment, the feedback method provides precoding matrix indicator (PMI) and channel quality indicator (CQI) feedback for each TP with rank 0 included. Having separate RI reports for different TPs means that different TPs can be sent to different ranks. Depending on the channel matrices of the TPs, in some situations the UE will be able to choose to receive all the data layers that it can handle from a single TP or from a set of associated TPs. In other words, for some realizations of the fading channel, there may be TPs that do not prefer the UE to receive data from some TPs. In this case, the UE allocates an RI corresponding to rank 0 for such TPs. Instead, the CQI index 0 may be used for this purpose or other signaling methods may be considered.

Thus, in certain embodiments, the UE feeds back the separate PMI, RI, and CQI for each TP, where the number of CQIs for each TP is determined by the corresponding RI. Feedback also includes an indication that the UE does not prefer to receive transmissions from a particular TP or TPs. In order to indicate to the eNB that the UE does not prefer to receive transmissions from a particular TP, one of a plurality of methods may be used. More specifically, in one method, the UE may use the CQI index 0, which is already specified in the resource, to indicate the out-of-range CQI. Instead, the UE adds a status corresponding to no transmission, i.e. rank-0, to the rank index table and transmits the index as RI. Instead, the UE may add all zero PMIs to the codebooks and feed back the corresponding RI and all zero PMIs when this situation occurs. Instead, communications with the UE may include bits to indicate whether the TP is not preferred by the UE. Instead, the UE will be able to signal it semi-statically (e.g., via RRC signaling) to the eNB using a bitmap.

Instead, in another embodiment, the feedback method provides independently selected sub-band feedback of a precoding matrix indicator (PMI), a rank indicator (RI) and a channel quality indicator (CQI) for each TP do. In a fading environment, channels from multiple TPs to the same UE may be completely independent, due to the geographical separation of TPs. As a result, applying frequency selective scheduling for that UE on multiple TPs may require allocating separate sub-bands to that UE for different TPs. This may result in more efficient use of frequency resources across the cell (s), as opposed to scenarios in which the UE is allocated the same sub-band on all TPs.

Transmissions on separate subbands of the same carrier from different TPs can be supported by feeding back separate PMIs / RIs / CQIs for each sub-band for different TPs. However, the need to support sub-band CSI feedback for each TP may require a large amount of feedback. However, by feeding back the CSI corresponding to the selective portions of the bandwidth, the amount of feedback can be significantly reduced.

For example, the UE may only feed back the CSI of the highest TP on each sub-band. In this context, the best TP can be defined, for example, as the TP providing the greatest throughput in the corresponding sub-band.

Also, for example, for each TP, the UE may feed back the CSI of only sub-bands with good channel quality (some specific criteria, e.g., the total SNR is greater than some thresholds) . Instead, the UE feeds back the CSI on the highest M sub-bands for each TP. This is an extension of the UE-selected sub-band feedback present in the current resources.

These selective feedback approaches may reduce feedback, but may impose some limitations on the performance of the eNB scheduler. (E.g., CSI feedback on all sub-bands, or CSI feedback on only selected sub-bands) may be semi-statically configured through high layer (e.g., RRC) signaling will be.

Thus, in certain embodiments, the UE feeds back a single-cell PMI / RI / CQI for each TP separately on some selected sub-bands. Depending on the selection method and also on the channel coefficients, the sub-bands used by the UE to report the PMI / RI / CQI for different TPs may or may not overlap. A plurality of sub-band selection methods are contemplated. For example, for each sub-band, the highest number of CSIs or the highest number of TPs is reported. CSI and the selected TP index must be fed back for each sub-band. The criteria for determining the highest TP or TPs may be defined based on throughput or received SNR. Also, for example, for each TP, the CSI on a specific number of sub-bands is reported. These sub-bands may include those with good channel conditions or simply the highest M sub-bands for that TP, where M is pre-defined and known by both the transmitter and the receiver. For each TP, the CSI parameters and indices of the highest M selected sub-bands must be fed back.

In another embodiment, transmission schemes for enabling feedback solutions to function with CoMP transmissions are described.

More specifically, in one embodiment, transmission schemes are provided to enable feedback solutions.

Considering the transmission schemes to enable feedback solutions, two main scenarios for CoMP operation can be considered. In the first scenario, all the TPs in the CoMP set are transmitted to the UE on the same frequency resources or sub-bands at a given time. In another scenario, the TPs in the CoMP set will be able to transmit to the UE on a given carrier at a given time on separate sub-bands. This is caused by the fact that the channels from different TPs to the UE are statistically independent and that separate frequency selective scheduling can be performed for different TPs. Since TPs are geographically separated, this approach will lead to more efficient frequency reuse and flexibility of resource management across the cell. These two scenarios are described in these sections.

More specifically, in one embodiment, for a multi-point transmission on the same sub-bands with the same codeword, a transmission scheme is provided that enables feedback solutions to work with CoMP transmissions. In this transmission scheme, it is assumed that all TPs are transmitted on the same time / frequency resources.

의) 벡터이다. 각각의 TP에 대해서, 만약 그 송신 랭크 R_i 가 데이터 레이어들 R의 전체 수 보다 작다면, 해당 특정 TP에 대한 x 내의 일부 데이터 레이어들의 배당을 설명하기 위해서 다른 매개변수가 이용된다. 따라서,

가 TP i로부터 송신된 데이터 레이어들의 인덱스 세트로서 규정된다. 송신은 수학식(7)에서 다음과 같이 기술될 수 있을 것이고:Additionally, in this transmission scheme, each TP _i is assigned a precoding matrix W _i selected from existing codebooks. In general, the dimensions of W _i may be different, as the transmission rank and also the number of antenna ports in TPs may be different. The transmission rank of TP i will be specified by R _i . By assumption, x is the length of data layers to be jointly transmitted by all TPs

Lt; / RTI > For each TP, if its transmission rank R _i is less than the total number of data layers R, then another parameter is used to account for the allocation of some data layers within x for that particular TP. therefore,

Is defined as the index set of data layers transmitted from TP i. The transmission can be described in Equation (7) as: < RTI ID = 0.0 >

Here, x (S _i ) represents the elements of x with indices in set S _i . H _i is the channel matrix from TP i to the UE, W _i is the precoder vector or matrix used by TP i, and n is the additional white Gaussian noise.

Thus, in certain embodiments, the TPs transmit the same data layers (or a subset thereof) on the same frequency / time resources using different precoding matrices. If the rank of the precoder used by the TP is less than the number of data layers, a subset of data layers is selected and transmitted by the corresponding TP. A subset of the layers is recognized by the UE for CQI calculation purposes.

To support this scheme in the general case of unequal ranks, a feedback mechanism is used that feeds back Common CQIs plus PMI / RI / CQI for each TP. A selection method based on maximizing the throughput is described in Equation (3). Data layer payouts (parameters S _i ) are predefined and are recognized by both the UE and the TPs. Also, for example, from equation (3), the data layer dividend may be derived dynamically. In the latter case, some additional signaling is similarly required to feed back S _i . the eNB may determine the final dividends based on feedback or other considerations and signal such a dividend to the UE.

In the special case where all TPs transmit with the same rank, a feedback mechanism that feeds back the PMI / CQI plus common RI / CQI for each TP may also be used. In this case, the relationship between the received signal and the data layers is simplified as follows:

In another embodiment, a transmission scheme that enables feedback solutions to function with CoMP transmissions provides distributed beamforming with phase corrections.

This scheme is supported by a feedback mechanism that feeds back the PMI / RI / CQI plus CQIs and phase differences for each TP, where some additional feedback (in the form of phase differences between TP and reference TP) Can be used. As described for this feedback mechanism, additional feedback can partially compensate for the effects of precoder codebook quantization and yield larger beam shaping gains. This scheme is described in equation (5). The proposed scheme supports transmission of rank > 1 by using one phase calibration for each layer of data on each TP. This is different from certain known methods in which only one phase value UE is used. In addition, this scheme allows to transmit different ranks from mixed ranks, i.e., different TPs. This may be useful when the number of antenna ports changes over TPs or when the TP's fading channel does not fully support many data layers, such as other TPs, at a particular instant.

를 곱할 수 있을 것이고, 여기에서

는 UE로부터 피드백된 페이즈 값이다. 부가적으로, 특정 실시예들에서, 만약 프리코더의 랭크가 데이터 레이어들의 수 보다 작다면, 데이터 레이어들의 서브세트가 대응하는 TP에 의해서 송신된다. 서브세트는 CQI 계산 목적들을 위해서 UE에 의해서 인지된다. Thus, in certain embodiments, the TPs transmit the same data layers on the same time / frequency resources using different precoding matrices. On TP i, on each data layer k

You can multiply by

Is the phase value fed back from the UE. Additionally, in certain embodiments, if the rank of the precoder is less than the number of data layers, a subset of the data layers is transmitted by the corresponding TP. The subset is recognized by the UE for CQI calculation purposes.

In another embodiment, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides multi-point transmission on the same sub-bands with different codewords.

One way to use the multiple TP placement scheme is to use TPs to increase the transmission data rates delivered to the UE. This can be accomplished by transmitting different data layers from different TPs, as described in connection with a feedback mechanism that feeds back the PMI / RI / CQI for each TP including rank-0.

In known LTE resources, data layers are formed from one or two transport blocks (TB). Thus, all TPs transmit the same TB and therefore use the same CQI (s). However, it is possible to increase the number of TBs by transmitting different TBs from different TPs, and thus support more than two TB transmissions to the UE. If this is the case, the use of TP-specific CQI feedback may be required. This scenario may be supported by a feedback mechanism that feeds back the PMI / RI / CQI for each TP that contains rank-0.

Thus, in certain embodiments, TPs will be able to transmit different data layers on the same time / frequency resources. Data layers from different TPs may be derived from different transport blocks. More than two TBs may be transmitted to the same UE. Additionally, in certain embodiments, rank-0 transmissions may be allocated to the TP. This will be signaled to the UE.

In another embodiment, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides transmit diversity over TPs.

More specifically, in certain embodiments, where the transmission scheme for enabling feedback solutions to function with CoMP transmissions provides transmit diversity across TPs, the Alamouti code may be transmitted over TPs . As shown in FIG. 10, the Alamouti codeword may be two consecutive (or otherwise densely-spaced) subcarriers in the frequency (similar to SFBC coding) or the same subcarrier frequency or two different But may be applied to a pair of REs, which may be two REs in temporal moments (preferably similar to densely-spaced) (similar to SFBC coding). Two layers of data are generated after Alamouti coding, each of which is dispatched to one TP, and the precoding before transmission in the TP is applied individually. The precoding applied by each TP is based on the feedback from the UE to the corresponding particular TP. For an arithmetic explanation of this method, assume that x ₁ and x ₂ are two modulation symbols. In the RE # 1, TP1 is the transmission of x ₁ w ₁ and a precoder and TP2 is transmitted to the x ₂ w ₂ precoder. Thus, the UE receives:

Assume that in the RE # 2, the channels are not significantly change over a period of two such REs and, TP1 is transmitted to the -x ^* ₂ precoder and w ₁ and TP2 is transmitted to the x ^* ₂ w ₂ to the precoder. Thus, the UE receives:

This is an Alamouti code with an effective channel matrix

To decode Alamuti codes at the UE, separate DM-RS ports are used for each TP. For example, DM-RS ports 7 and 8 as specified in Rel-10 can be used for each TP, which is transmitted on the same REs and separated by different orthogonal codes. If such transmissions are configured for the UE as a transmission mode, the DM-RS ports used may be pre-defined and may not need to be signaled to the UE.

Thus, in certain embodiments, in two TP CoMP set scenarios, each TP can transmit one layer of data on the same time / frequency resource as the other TPs. The mapping of the layers to TPs may be performed based on 2-tx transmit diversity (Alamouti coding) as specified in LTE, but Alamouti coded streams may then be precoded and each TP Lt; / RTI > Separate DM-RS ports may be used for each TP for data demodulation in the UE.

에 의존하기 때문에, TP i에 대한 최적의 프리코딩 벡터 W_i 가 대응하는 채널 H_i 를 기초로 개별적으로 그리고 단독적으로 선택될 수 있다. 만약 TPs의 수가 2 초과라면, (LTE Rel-8 및 Rel-10에서의 4-안테나 알라무티와 유사하게) 다른 쌍들이 이용하는 자원과 상이한 자원 내에서 각각이 쌍이 하나의 알라무티 코드워드를 송신하도록, TPs가 쌍을 이룰 수 있을 것이다. The performance of the Alamouti code is the norm of the channel matrix,

The optimal precoding vector W _i for TP i can be selected individually and singly based on the corresponding channel H _i . If the number of TPs is greater than 2, then each pair in the resource that is different from the resource used by the other pairs (similar to the 4-antenna Alamouti in LTE Rel-8 and Rel-10) , TPs will be able to pair.

One approach is to transmit Alamouti codewords on orthogonal sub-spaces. In other words, the precoding vectors must be selected such that the paired layers from the two TPs occupy a single dimension in the received vector space. Also, the different layers must be orthogonal in the receiver vector space. In this way, different data layers, corresponding to different Alamouti codewords, are easily separated at the receiver side and a simple Alamouti decoder can be applied.

An alternative approach to jointly selecting precoding matrices is to select a PMIs to derive a valid channel matrix with respect to the actual channel matrices and precoding matrices and to maximize the capacity (corresponding to a valid channel matrix) . In this approach, a more advanced receiver structure may be needed for data detection.

In this way, all TPs must transmit at the same rank, so that the layers from the two TPs can form a pair of Alamouti codewords. Also, the data on the different TPs comes from the same codeword. Thus, TPs also share the CQI. However, each TP may use a different PMI than the other TPs. As a result, a feedback mechanism that feeds back the PMI / RI / CQI for each TP including rank-0 may be used to support this transmission mode.

In general, it is possible to transmit R layers of data from each TP and apply Alamuti codes individually on each layer, and an example of R = 2 is shown in FIG. 11 with two TPs. This leads to the transmission of multiple Alamouti codewords on the same resources. The process of selecting precoding matrices may be more complex in this general scenario and may need to be done jointly for all TPs.

Thus, in certain embodiments, in two TP CoMP scenarios, TPs will be able to transmit the same number of data layers on the same time / frequency resource. Layer mapping is performed so that each layer of TP # 1 is paired with one layer of TP # 2, and each pair of layers forms an Alamouti code. A separate DM-RS port may be used for each layer transmitted from each of the TPs.

In another embodiment, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides inter-TP transmit diversity without precoding.

An inter-TP transmit diversity scheme with precoding, using both precoding and transmit diversity gains, is described above. In an alternative embodiment, if each of the two TPs has one antenna port, the precoding operation may be omitted, and after Alamouti coding, each pair of symbols may be sent for each TP, It can be transmitted without precoding.

If each of the two TPs has two antenna ports, a 4-tx transmit diversity scheme employed in LTE Rel-8, or referred to as SFBC + FSTD4, It can be applied throughout. This scheme will only have the advantage from diversity gain, but it will have the advantage of not requiring PMI feedback from the UE, thus improving the performance of UEs with relatively large mobility.

To decode Alamouti codes, a TP specific RS is transmitted from each TP. As the common RS (CRS) needs to be transmitted from all TPs to support the legacy UE, the DM-RS as defined in Rel-9/10 may be reused for this purpose, or a new TP Specification RS ports may be defined. Precoding does not apply to DM-RS ports within the allocated RBs.

Thus, in certain embodiments, Rel-8 2 -tx and 4-tx transmit diversity are applied over TPs to form transmit diversity for CoMP transmission. TP specific RS ports may be specified or DM-RS ports as defined in Rel-9/10 are not applied for DM-RS ports within the RBs allocated for precoding, It can be reused.

In another embodiment, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides open-loop spatial multiplexing CoMP transmission.

In such transmissions, the same layers of data may be transmitted from different TPs, or different layers of data may be transmitted from different TPs, and precoding or pre-defined precoding is not applied in TPs. No PMI feedback is required, only the CQI is fed back from the UE.

In another embodiment, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides multi-point transmission on separate sub-bands.

In the CoMP scenario, where the TPs are geographically separated, both their large-scale fading (shadowing) and small-scale fading (multiple path) channels to the UE are independent from each other. Thus, if the UE finds a good channel from one TP on the sub-band, there is no need to induce the UE to look for good channels from other TPs on the same sub-band. In such a situation, forcing all TPs to use the same sub-band for transmission to the same UE would prevent the system from enforcing the entire potential gain available through frequency selective scheduling. In other words, by allowing the TPs to transmit on separate sub-bands, TPs can individually perform frequency selective scheduling that can derive performance gains for each UE. From a system level perspective, in contrast to transmissions on the same sub-bands from all TPs, this approach may require a greater overall bandwidth for transmission to the UE. However, it should be noted that by having frequency reuse across the cell (s), the overall bandwidth utilization may not be affected by this approach. For example, in Figure 12, UE 1 is scheduled on sub-band 1 (sb 1) from TP # 1 and on sub-band 2 (sb 2) from TP # 2, Since the corresponding channels are optimal for each individual TP. At the same time, TP # 3 can reuse sb 1 to service UE # 2. Since UE # 2 is within the coverage area of TP # 2, sb 2 can not be used for it because TP # 2 has already used sb2 to service UE # 1. It should be noted that separate sub-band transmission provides a scheduler with greater resilience that may allow more efficient scheduling.

Thus, in certain embodiments, transmissions on separate sub-bands from different TPs may be utilized to fully utilize the frequency selective scheduling gains available from the plurality of TP to UE propagation channels . If the same MCS and the same TP are used for all sub-bands, transmission on separate (non-overlapping) subbands from multiple TPs will cause the current down It can be supported by reusing the link acknowledgment structure (DCI). Otherwise, the DL acknowledgment structure may need to be modified to accommodate the overhead required to support the transmission on separate sub-bands (e.g., on which RBs it is scheduled and on which MCSs Is used to indicate to the UE).

More specifically, in particular embodiments, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides multi-point transmission on separate sub-bands utilizing codeword partitions.

이 되도록, 세그먼트 길이들 G_i 이 배열된다. If the UE is scheduled to receive data from multiple TPs on different sub-bands, one possibility would be to split each codeword into different segments and transmit each segment on a different TP. An example of code word segmentation is shown in FIG. CRC attachment, code block segmentation, channel coding, rate matching, and code block sequencing are implemented as specified in well-known resources (e.g., see 3GPP TSG-RAN TS 36.212). Rate matching is performed based on the total number of REs allocated for all TPs. The code word length at the output of the code block sequencing is indicated by G. By codeword partitioning, the entire codeword is destroyed with n disjoint segments, where segment i has a G _i length and is then added to the TP for additional processing, such as scrambling, modulation, layer mapping, precoding, #i.

, The segment lengths G _i are arranged.

The segmentation shown in FIG. 13 is an example in which the first G1 coded bits are allocated for TP # 1, then the G ₂ bits are allocated for TP # 2, and so on. In general, any segmentation of the codeword may work. The codeword segmentation referred to herein differs from code block segmentation, which is part of channel coding.

The codeword segmentation of Figure 13 is shown for a single codeword only. If the UE is scheduled for more than one codeword, the same procedure can be applied separately for each codeword.

If different TPs have the same cell ID, the scrambling sequences for all TPs may be the same, as in CoMP scenario 4 with RRHs. In such a scenario, most of the processing may be performed in a central unit, referred to in the Macro eNB, and the precoded signals may be transmitted as TPs for resource mapping and transmission. This is suitable for scenarios where the RRHs have low processing capabilities.

To support this scheme, feedback from the UE may include separate PMIs, RIs, and CQIs for all associated TPs on all sub-bands. This can be done by a feedback mechanism that feeds back the PMI / RI / CQI for each TP with rank-0. However, in such a scenario, there is no need for joint calculation of CSI and the CSI of each TP is calculated as in the single-cell approach (because only one TP on each sub-band is transmitted to the UE). To reduce the feedback overhead, the UE may use an optional feedback mechanism that independently selects sub-band feedback of PMIs / RIs / CQIs for each TP. Examples of such include either feeding the best CSI of the best TP for each sub-band, or feedbacking the best M sub-bands for each TP.

To support this scheme, it may be necessary for the eNB to derive a common CQI for MCS allocation. One way to derive this information is to use wideband CQI feedback from the UE. Instead, the eNB may use the available CQIs for that eNB for all scheduled sub-bands to derive a single CQI for acquiring the MCS. One approach to this is to use the worst CQI among all the CQIs of the assigned sub-bands. An alternative approach is to estimate the SNR of each sub-band based on its CQI and then averaging over them (e.g., by using Exponential Effective SNR Mapping (EESM)) . The averaged SNR can be used to obtain a single CQI for all subbands and the MCS to be used across these separate subbands is determined therefrom. If a single CQI is derived from the eNB, only one MCS should be included in the DL acknowledgment. Therefore, the existing LTE downlink grant structure defined in Rel-8/9/10 could be reused. By doing this, transmissions on separate sub-bands from different TPs can become transparent to the UE, since the UE does not need to know what sub-band is being transmitted from which TP.

Thus, in certain embodiments, different TPs will be able to transmit different parts of the codeword on separate sub-bands. A single MCS is used across all scheduled sub-bands.

In certain embodiments, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides multi-point transmission by transmitting the same codeword (TB) on different sub-bands.

More specifically, in this alternative approach for taking advantage of transmission on separate sub-bands, the output of the channel encoder is used by all TPs. However, each TP applies a rate matching processing operation separate from the other TPs. As shown in FIG. 14, the output of the channel coding is transmitted to all TPs and each TP, and depending on the number of REs, rate matching is applied, and then code block concatenation is applied.

In this scheme, different TPs may use different MCSs and there is no need to average CQIs.

Since the same data is transmitted on a plurality of unrelated sub-bands, if the receiver is properly designed, a frequency diversity gain is expected. This could be done by calculating the likelihood ratios (LLRs) of information bits on each of the sub-bands and then by combining them together prior to making a hard decision .

Any feedback mechanism that provides single cell PMIs, RIs, and CQIs may be used. To support this scheme, downlink acknowledgment is designed to allocate different MCSs for each sub-band, while maintaining one TB for total data traffic.

More specifically, in certain embodiments, different TPs will be able to utilize the output of the same channel encoder and apply rate matching separately. Each TP will then be able to transmit its codeword on a separate sub-band from the other TPs. Different MCSs are allocated for each sub-band and this information need not be signaled to the UE.

In particular embodiments, a transmission scheme for enabling feedback solutions to function with CoMP transmissions provides multi-point transmission by transmitting separate codeword (s) on separate sub-bands do.

To increase the multiplexing gain or data rate of the UEs, CoMP structures may be used. Separate sub-band transmissions from different TPs are scenarios that facilitate the utilization of this possibility of CoMP. When different TPs are scheduled to be transmitted on separate sub-bands to service the UE, each TP may transmit a separate codeword or TB. As each TP transmits on a different sub-band, the MCSs corresponding to these codewords may also be different. In this manner, a plurality of TBs may be transmitted to the UE simultaneously on different sub-bands.

Feedback mechanisms that provide single-cell detached CSI feedback or single-cell selective feedback may be used with such a transmission scheme.

To support this scheme, separate downlink acknowledgments may be used to schedule different data transmissions for the UE. In another embodiment, a new downlink grant may be designed that includes a different MCS payload for independent sets of sub-bands transmitted from different TPs.

Thus, in certain embodiments, each TP may have a separate TB, and the TP applies channel coding on such TB. Different MCSs may be allocated for each TB. The different TBs may then be transmitted on the sub-bands separated from the different TPs.

In other embodiments, a method for constructing feedback and transmission schemes that work with CoMP transmissions is described.

The various feedback schemes and transmission schemes described may be applied for different scenarios. However, in order to reduce the complexity at both the eNB and the UE to support CoMP transmission, it is desirable to allow such schemes to be configured. On the other hand, it is desirable to allow sufficient resiliency in the eNB to determine what transmission schemes can be used for each sub-frame, and that such switching between the transmission and feedback schemes is preferably desirable for the UE It should not give a minimum impact or impact.

More specifically, in one embodiment, a method for constructing feedback schemes that work together with CoMP transmissions is described.

As described, there are various schemes for the UE to derive the appropriate PMI, RI, and CQI and to feed them back to the eNB. Such methods of deriving such parameters may be a UE implementation problem as long as they meet certain performance requirements. Generally, in the case of a plurality of TPs, different PMIs need to be derived and fed back. For RI and CQI, there are different approaches, such as deriving and feedbacking separate RI and CQIs for each TP, or deriving and feeding common RI and CQIs for all TPs.

Another consideration in the feedback design is backward compatibility. In general, it is desirable to reuse existing feedback schemes (modes) where possible (i.e., the modes developed in previous resource releases), and thus the introduction of new schemes, Lt; / RTI > Obviously, some modifications to these existing modes may need to be considered.

Some principles that can be used as a baseline for feedback design in closed-loop CoMP transmission are shown in FIG. More specifically, FIG. 15 shows an example of a feedback report using time division multiplexing, where a joint rank (over TPs) is derived and fed back to the eNB over uplink channels (e.g., via PUCCH or PUSCH) Lt; / RTI > Following such a rank report, a CQI / PMI report can be fed back to TP # 1 followed by a CQI / PMI report for TP # 2. The same report formats as those specified in Rel-8 may be used for these two reports and they may be transmitted on the PUCCH or PUSCH in subsequent subframes. Following this, the joint CQI report may also be fed back.

Alternatively, a rank report, separate PMI / CQI reports for each TP, and joint CQI reports for multiple TPs may be encoded and transmitted together. The transmission of such jointly encoded multi-TP feedback reports would be more appropriate for transmission on the PUSCH, but modification of the PUCCH to accommodate such could also be possible.

Thus, multiple embodiments relate to a feedback report for closed-loop CoMP transmission. For example, one embodiment involves supporting a common rank (one rank for all TPs) or feedback of separate ranks for each TP. The separate ranks for each TP are jointly coded and fed back together in the same rank report. In another embodiment, for each TP, separate CQI / PMI reports as specified in Rel-8 or Rel-10 may be fed back to the eNB. CQI feedback in such reports may assume a single TP transmission and may be derived in the same manner as specified in previous releases. In another embodiment, CQI / PMI reports for each TP may be sent on the PUCCH or PUSCH. Different reports for different TPs will be able to be transmitted in different subframes in a time multiplexed (TDM) manner (e. G. Could be transmitted on a periodic report on the PUCCH). If the subband CQI / PMI reports for each TP are configured, then such reports are reported sequentially for the second TP following the subband CQI / PMI reports for one TP, and so on (TDM) scheme on a PUCCH. Or subband CQI / PMI reports of different TPs are sequentially interleaved and transmitted in different PUCCHs. Instead, all reports for different TPs can be multiplexed and / or encoded together (e.g., transmitted in an aperiodic report on the PUSCH). In another embodiment, in addition to the reports, CQI reports can be configured, where a joint CQI is derived assuming that the same layers of data can be transmitted from each TP. Such reports may be transmitted in a multiplexed manner with other CQI / PMI reports on a TDM scheme (e.g., on a PUCCH with a periodic report structure), multiplexed with other CQI / PMI reports, , On a PUSCH as an aperiodic report). In another alternative, a CSI feedback report may be sent on both PUCCH and PUSCH, for example, an RI report, a per-TP wideband CQI / PMI report, and a wideband joint CQI may be transmitted on the PUCCH in a TDM manner While the subband PMI / CQI and subband joint CQI for each TP may be transmitted on the PUSCH.

In known resource releases, different types of feedback modes are defined for deriving and reporting different types of CQIs / PMIs, including wide band reports, selected sub-band reports and all sub-band reports. With the introduction of multiple TPs in a system that supports CoMP operation, feedback reports for different TPs will follow the same report style as previously specified.

Additionally, a plurality of alternative embodiments are associated with closed-loop CoMP transmission. For example, in one embodiment, Rel-8 feedback modes 1-1, 2-1 for PUCCH, and modes 31-, 1-2, and 2-2 for PUSCH may be used for closed- It can be expanded. In such modes, for each TP, feedback reports of the same types as specified in Rel-8 may be used. In addition, joint CQI reports may be derived and fed back. In another embodiment, for a selected sub-band report, the selection of the highest-M sub-bands may be based on the joint CQI from multiple TPs instead of the individual CQIs for each TP. The UE will then be able to derive and feed back a separate CQI / PMI report for each TP, assuming a separate transmission from each TP based on the selected sub-bands. The UE will also be able to derive and feedback joint CQIs for each selected sub-band by assuming a joint transmission from all TPs.

For CoMP transmit diversity and open-loop space multiplexed transmissions, only CQIs that can be considered feedback. The feedback modes may be based on Modes 1-0 and 2-0 on the PUCCH, Modes 2-0 and 3-0 on the PUSCH, and Separate CQIs for each TP are reported. The joint RI / CQI reports may be fed back for an open-loop CoMP transmission on top of separate CQI feedback for each TP, which may cause the eNB to switch dynamically between the CoMP and the separate per TP transmission .

Multiple embodiments relate to open-loop CoMP transmission. For example, feedback modes 1-0, 2-0 for PUCCH, and modes 2-0 and 3-0 for PUSCH may be considered as a baseline for feeding back separate CQIs for each TP will be. Also, for example, a joint CQI derived based on transmissions from all TPs may be included in the feedback.

The feedback modes may be semi-statically configured through higher-layer (e.g., RRC) signaling similar to feedback configurations in previous releases.

In another embodiment, a method for constructing transmission schemes that work together with CoMP transmission is described.

In the feedback modes as described, the eNB may configure the UE to feed back a separate CQI / PMI report for each TP. The eNB may also configure the UE to derive and feedback the joint CQI feedback report for all TPs. This allows sufficient resilience in the eNB for its scheduling. For example, the eNB may schedule a joint transmission or may simply schedule a single TP transmission to the UE. In this way, a single closed-loop CoMP transmission mode can be configured to accommodate dynamic switching between CoMP and non-CoMP transmission.

In CoMP transmissions, multiple transmissions may be supported provided there is a one-to-one mapping between DM-RS ports and layers. These transmissions will be the same for the UE with respect to UE reception. For example, transmission is supported where each of the two TPs transmits a different layer to the UE. Also, for example, transmission is supported where each of the two TPs transmits the same two layers to the UE.

Other transmission modes may be configured for CoMP transmission. For example, transmit diversity with a precoding scheme can be constructed. Instead, transmit diversity without precoding may also be constructed.

Thus, in certain embodiments, the network may configure the use of closed-loop space multiplexed CoMP transmission modes. The transmission mode will be able to support separate CQI / PMI reports for each TP. In addition, joint CQI feedback may be constructed. Dynamic switching between CoMP and non-CoMP transmission may be supported by this mode. Also, in certain embodiments, the network may configure the use of an open-loop spatial multiplexed CoMP transmission mode, which does not require PMI feedback from the UE. Pre-defined or eNB determined precoding vectors may be applied in TPs. Also, in certain embodiments, closed-loop and open-loop spatial multiplexed CoMP transmissions may be included in one transmission mode referred to as a spatial multiplexed CoMP transmission mode. Using the configuration of different feedback modes at the UE, switching between closed-loop and open-loop operations can be achieved. For example, if the UE is configured with CQI-only (no PMI) feedback, open-loop transmission may be used, whereas if the UE is configured with PMI / CQI feedback, closed- loop transmission may be used . Also, in certain embodiments, transmit diversity with or without precoding may be configured for two TPs. Alamuti types of encoding will be applied to generate pairs of coded symbols and these pairs will be able to be transmitted from potentially different TPs. The CQI calculation in the UE for feedback needs to assume that Alamouti coding is used. Transmit diversity across multiple TPs may be configured as separate transmission modes or may be utilized as a fall-back scheme for joint spatial multiplexing transmissions across multiple TPs.

In another embodiment, a method for constructing transmission schemes that provide DCI support for CoMP transmission is described.

Known DCI formats may be used for CoMP transmissions, thereby making the CoMP transmissions transparent to the UE, or at least minimizing the impact on existing signaling structures. (The same data layers are transmitted from multiple TPs), in a joint transmission, the same DM-RS ports could be used for each TP. Thereby, there is no need to signal additional DM-RS ports, and a single DCI format such as DCI format 2C for TM9 can be used. If different layers are sent from different TPs, different DM-RS ports may need to be allocated for each TP. However, as long as there is a one-to-one association between the DM-RS port and the layer, additional signaling for UE demodulation is not required. In general, up to four DM-RS ports need to be supported for CoMP transmission.

In other embodiments, a method for allowing CSI-RS transmission in a cell having a plurality of TPs sharing the same cell ID is described.

One motivation beyond the proposed schemes is to share the same CSI-RS configuration between different TPs in a frequency division manner. By doing so, it will be appreciated that less CSI-RS configurations are needed in the cell and UE complexity in deriving CSI from such CSI-RS is reduced.

In one embodiment, one Rel-10 CSI-RS configuration is used for the macro eNB. The same configuration is also used by RRHs. This configuration is signaled for all Rel-10 and Rel-10 post-UEs. Other CSI-RS configurations are used for RRHs and signaled with only newer UEs (e.g., UEs supporting CoMP). These two CSI-RS configurations may differ only by the CSI-RS patterns in the subframe. The second CSI-RS configuration is shared among all RRHs in a frequency division multiplexing manner. Since the CSI-RS configuration can be applied to all RBs within the system bandwidth, each RRH transmits the CSI-RS on a particular sub-band (frequency band) within each configured CSI-RS subframe. A sub-band comprising CSI-RS for each RRH may be hopped from one CSI-RS subframe to another, such that the total system bandwidth is equal to or greater than a certain number of CSI-RS subframes Lt; / RTI > The number of subframes required to cover the entire bandwidth by a single RRH is equal to the number of RRHs in the cell. The hopping scheme can be a specific pattern or as shown in FIG. 16, where the sub-band positions of each RRH are cyclically transited to each transmit opportunity.

For example, a macro eNB with 2 RRHs in a 10 MHz system bandwidth is assumed. The CSI-RS configuration as shown in FIG. 17 uses the resource element (RE) # 9 of the ODFM symbols # 5 and # 6 for the antenna port 0/1 and the ODFM symbol # 5 And resource element (RE) # 2 of # 6. The scheme shares a CSI-RS configuration pattern between 2 RRHs as follows: the configuration is allocated for RRH1 for the frequency domain spanning RB # 0 to 24 and then the same configuration is used in this example, in the 10 MHz system band Is allocated to RRH2 for the frequency region corresponding to RBs # 25 to 49, where the total number of RBs in the width is 50. The number of sub-bands (corresponding to the number of RRHs) and the number of antenna ports per sub-bands UEs supporting CoMP as redundant information in semi-static (e.g., RRC) Lt; RTI ID = 0.0 > 11 UEs). ≪ / RTI > The sizes in the RBs of the different sub-bands may also be signaled, if they are different. This allocation is then cyclically timed so that the UE can measure the wideband channel from each RRH as shown in FIG. The cycling period and pattern can vary and depend on the number of RRHs and channel conditions.

RTI ID = 0.0 > RRH < / RTI > antenna ports need only be signaled once in a semi-static manner. By recognizing the number of sub-bands and the RRH hopping pattern, as the RRHs hop across sub-bands in time, the UE can determine the number of supported antenna ports in each sub-band in each CSI- Can be derived.

The scheme presented above may be extended in a plurality of different ways. For example, to increase the accuracy of CSI measurements, the entire macro eNB coverage area may be divided into areas, each of which is configured with one CSI-RS configuration for UEs that support CoMP, The region contains more than one RRH. All RRHs in the same region may share the same CSI-RS configuration as described above. This will allow CoMP UEs to report CSI only for configured RRHs, instead of reporting CSI for all RRHs.

Other extensions include RRHs sharing the same configuration (same resources / patterns, offsets, periodicity) across the entire band, but the CSI-RS for each RRH is differentiated by CDM (code division multiplexing).

Such a scheme for allowing CSI-RS transmission in a cell with multiple TPs sharing the same cell ID provides a number of advantages. For example, methods have backward compatibility for legacy UEs. The previously proposed scheme is transparent to non-CoMP (e.g., Rel-10) UEs. The configuration is preserved for the macro-eNB and signaled to UEs after Rel-10 and Rel-10. Additionally, in such a scheme, the need for an RRH association for CSI feedback is eliminated. In order to semi-statically reconfigure the CSI-RS configuration as needed, the eNB now uses feedback because it has full feedback from all RRHs. Additionally, such a scheme reduces unnecessary overhead signaling. the eNB will not need to track when UEs move between RRHs and thus will not need to signal a new CSI configuration at each time. Additionally, in such a scheme, the CSI latency feedback report is reduced because only one offset is used. The periodicity may be adjusted to the number of RRHs supported within the macro eNB cell or region. Additionally, such a scheme reduces the impact of interference on neighboring cells, since only one extra CSI-RS configuration is needed. Additionally, in such a scheme, rate matching is simplified because the location of the CSI-RS is known and fixed. Additionally, in such schemes, there is no need for signaling whenever the UE moves from one RRH coverage to another. The problem of the artificial handover type generated by the existing scenario is eliminated. In addition, management and distribution of the CSI-RS configuration is simplified.

Thus, in certain embodiments, the CSI-RS for each TP is transmitted on the same pattern and at the same bandwidth, but on different sub-bands. The sub-bands in which the CSI-RS is transmitted for each TP temporally hop across the entire system bandwidth. The hopping pattern of CSI-RS for each TP follows the same cycle but with different offsets. The CSI-RS for the macro-eNB may be sent according to the same rules as the TP, or may be sent separately across the entire system bandwidth.

FIG. 18 illustrates an example of a system 1800 suitable for implementing one or more embodiments disclosed herein. In various embodiments, system 1800 includes a processor 1810, a network connection interface 1820, a random access memory (RAM) 130, a read only memory (ROM) 140, a secondary storage 1850, / Output (I / O) devices 1860. The processor 1810 may be referred to as a central processor unit (CPU) or a digital signal processor (DSP). In some embodiments, some of such components may not be present, or may be combined in various combinations with each other or with other components not shown. Such components may be located within a single physical entity or within more than one physical entity. All of the actions described herein as taken by processor 1810 may be taken by processor 1810 alone or by processor 1810 in combination with one or more components not shown or shown in FIG.

The processor 1810 executes instructions, codes, computer programs, or scripts that such a processor can access from the network connection interface 1820, RAM 1830, or ROM 1840. Although only one processor 1810 is shown, multiple processors may be present. Thus, although directives may be described as being executed by processor 1810, they may be executed concurrently, sequentially, or otherwise by one or more processors 1810 implemented as one or more CPU chips will be.

In various embodiments, the network connection interface 1820 may be a modem, modems banks, Ethernet devices, universal serial bus (USB) interface devices, serial interfaces, token ring ) Devices, radio distributed transceiver devices such as fiber distributed data interface (FDDI) devices, wireless local area network (WLAN) devices, code division multiple access (CDMA) devices, global system for mobile communication Connection to networks including a Personal Area Network (PAN), such as radio transceiver devices, long term evolution (LTE) radio transceiver devices, worldwide interoperability for microwave access (WiMAX) devices and / or Bluetooth Lt; RTI ID = 0.0 > interfaces. ≪ / RTI > These network connection interfaces 1820 may be used to communicate with the Internet or one or more telecommunication networks or other networks in which the processor 1810 can communicate with the Internet or one or more telecommunication networks, It will be possible to do.

The network connection interface 1820 may also be capable of wirelessly transmitting or receiving data in the form of electromagnetic waves, such as radio frequency signals or microwave frequency signals. The information transmitted or received by the network connection interface 1820 may include data processed by the processor 1810 or directives to be executed by the processor 1810. [ The data may be ordered according to different sequences that may be required to process or generate the data or as required to transmit or receive the data.

In various embodiments, RAM 1830 may be used to store the volatile data and directives that are executed by processor 1810. The ROM 1840 shown in FIG. 18 may similarly be used to store data and directives that are read during the execution of the directives. The secondary storage device 1850 is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data, or RAM 1830 is used to store all of the working data It may be used as an overflow data storage device. Secondary storage 1850 may also be used to store programs that are loaded into RAM 1830 when the program is selected for execution. I / O devices 1860 may be any of a variety of devices, including liquid crystal displays (LCDs), light emitting diode (LED) displays, organic light emitting diode (OLED) displays, projectors, But are not limited to, touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, printers, video monitors, / Output devices.

FIG. 19 illustrates a wireless-enabled communication environment that includes an embodiment of a client node as implemented in an embodiment of the present invention. Although illustrated as a mobile phone, the client node 1902 may take various forms, including a wireless handset, a pager, a smart phone, or a personal digital assistant (PDA). In various embodiments, the client node 1902 may also include a portable computer, a tablet computer, a laptop computer, or any computing device operable to perform data communication operations. Many suitable devices are combined with some or all of these functions. In some embodiments, the client node 1902 is not a general purpose computing device such as a portable computer, a laptop computer, or a tablet computer, but is a special-purpose communication device such as a communication device installed in a vehicle. Similarly, client node 1902 may be, include, or be a device that has similar capabilities but can not be moved, such as a desktop computer, set-top box, or network node. In these and other embodiments, client node 1902 may support special activities such as games, inventory control, job control, task management functions, and the like.

In various embodiments, the client node 1902 includes a display 1904. In these and other embodiments, the client node 1902 may also include a touch sensitive surface, keyboard, or other input keys 1906 that are typically used for input by a user. Similarly, the input keys 1906 may be a reduced or full size alphanumeric keyboard such as the QWERTY, Dvorak, AZERTY, and sequence keyboard types, or may be a traditional numeric keypad with alphabetic characters associated with the telephone keypad . Similarly, an input key 1906 may be navigational (not shown) that can be pressed inward to provide a track wheel, an exit or escape key, a trackball, ) Or function keys. Similarly, the client node 1902 may present choices for the user to select, controls for the user to operate, and cursors or other indicators for the user to direct.

Client node 1902 may additionally accommodate data input from a user, including numbers for dialing or various parameter values for configuring the operation of client node 1902. Client node 1902 may additionally execute one or more software or firmware applications in response to user instructions. These applications may configure the client node 1902 to perform various customized functions in response to user interaction. Additionally, client node 1902 may be over-the-air (OTA), e.g., a wireless network access node 1908 (e.g., a base station), a server node 1916 (e.g., Host computer), or peer client node 1902. [

Among the various applications executable by the client node 1902 is a web browser, which allows the display 1924 to display a web page. The web page may be obtained from the server node 1916 via a wireless connection with the wireless network 1912. As used herein, wireless network 1912 is broadly referred to as any network that utilizes at least one wireless connection between nodes of two networks. Similarly, various applications may be obtained from a peer client node 1902 or other system through a connection to a wireless network 1912 or any other wireless-enabled communication network or system.

In various embodiments, the wireless network 1912 includes a plurality of wireless sub-networks (e.g., cells having corresponding coverage areas). As used herein, the wireless sub-networks may variously include a mobile radio access network or a fixed radio access network. In these and other embodiments, client node 1902 transmits and receives communication signals, which are communicated to and from wireless network nodes by wireless network antennas (e.g., cell towers) do. Again, communication signals are used by the wireless network access nodes to establish a wireless communication session with the client node 1902. As used herein, network access nodes broadly refer to any access node of a wireless network. The wireless network access nodes are each coupled to wireless sub-networks, which in turn may be connected to the wireless network 1912.

In various embodiments, the wireless network 1912 is coupled to a physical network 1914, such as the Internet. Through the wireless network 1912 and the physical network 1914, the client node 1902 accesses information on various hosts, such as the server node 1916. In these and other embodiments, the server node 1916 may be capable of providing content that can be viewed on the display 1904 or utilized by the client node processor 1810 for those operations. Instead, the client node 1902 may access the wireless network 1912 through a peer client node 1902 acting as an intermediary, in a relay type or hopping type connection . Alternatively, client node 1902 may be tethered and may obtain data from the linked device connected to wireless network 1912. Those skilled in the art will recognize that many such embodiments are possible and that the foregoing is not intended to limit the spirit, scope, or intent of the disclosure.

Figure 20 shows a block diagram of an exemplary client node implemented with a digital signal processor (DSP) in accordance with an embodiment of the invention. Although various components of client node 1902 are shown, various embodiments of client node 1902 may include listed components or a subset of additional components that are not listed. As shown in FIG. 20, the client node 1902 includes a DSP 2002 and a memory 2004. As shown, the client node 1902 includes an antenna and front end unit 2006, a radio frequency (RF) transceiver 2008, an analog baseband processing unit 2010, a microphone 2012, earpiece speaker 2014, a headset port 2016, a bus 2018 such as a system bus or an I / O interface bus, a removable memory card 2020, a universal serial bus (USB) port 2022 A short range wireless communication sub-system 2024, an alarm 2026, a keypad 2028, a liquid crystal display (LCD) 330 that may include a touch sensitive surface, an LCD controller 2032, a charge- Further includes a power management module 2040 operatively coupled to a power storage unit, such as a camera 2034, a camera controller 2036, a global positioning system (GPS) sensor 2038, and a battery 2042 It will be possible. In various embodiments, the client node 1902 may include other types of displays that do not provide a touch sensitive screen. In one embodiment, the DSP 2002 communicates directly with the memory 2004 without passing through the input / output interface 2018.

In various embodiments, DSP 2002 or some other form of controller or central processing unit (CPU) may be implemented in accordance with embedded software or firmware stored in memory 2004 or stored in memory contained in DSP 2002 itself , And to control various components of the client node 1902. In addition to embedded software or firmware, the DSP 2002 may be coupled to a memory card 2020 through an information carrier, such as a portable data storage medium, similar to the memory card 2020 stored in the memory 2004, or via a wired or wireless network communications It will be possible to run other applications that are made possible. The application software may include a compiled set of machine-readable instructions that constitute the DSP 2002 to provide the desired functionality or may be executed by an interpreter or compiler to configure the DSP 2002 indirectly. Lt; / RTI > high-level software directives.

It is to be appreciated that the antenna and front end unit 2006 may provide for conversion between wireless signals and electrical signals such that the client node 1902 may be a cellular network or some other available wireless communication network or peer client node 1902 To transmit and receive information. In an embodiment, the antenna and front end unit 1806 may comprise a plurality of antennas to support non-forming and / or multiple-input multiple-output (MIMO) operations. As is known to those skilled in the art, MIMO operations may provide spatial diversity that can be used to overcome difficult channel conditions or to increase channel throughput. Similarly, the antenna and front end unit 2006 may include antenna tuning or impedance matching components, an RF power amplifier, or a low noise amplifier.

In various embodiments, the RF transceiver 2008 provides frequency transitions, conversion of received RF signals to baseband, and conversion of baseband transmission signals to RF. In some explanations, a radio transceiver or RF transceiver may perform at least one of: modulation / demodulation, coding / decoding, interleaving / deinterleaving, spreading / despreading, inverse fast Fourier transforming ; Other signal processing functions such as IFFT / FFT, cyclic prefix add / drop, and other signal processing functions. For clarity, the description herein is intended to distinguish between the RF and / or radio stages and the description of such a signaling process, and conceptually to the analog baseband processing unit 2010 or DSP 2002 or other central processing unit, Allocate processing. In some embodiments, the RF transceiver 2008, the antenna and portions of the front end 2006, and the analog baseband processing unit 2010 may be implemented within one or more processing units and / or in an application specific integrated circuit (ASIC) It can be combined.

The analog baseband processing unit 2010 includes various analog processing of inputs and outputs such as inputs from microphone 2012 and headset 2016 and outputs from earpiece 2014 and headset 2016 It will be able to provide analog processing. To this end, the analog baseband processing unit 2010 may have ports for connection to an earpiece speaker 2014 and an embedded microphone 2012 that allows the client node 1902 to be used as a cell phone. The analog baseband processing unit 2010 may further include a port for connection to a headset or other hands-free microphone and speaker configuration. The analog baseband processing unit 2010 may provide a digital-to-analog conversion of one signal direction and an analog-to-digital conversion of the opposite signal direction. In various embodiments, the functionality of at least some of the analog baseband processing unit 2010 may be provided by the digital processing components, for example, by the DSP 2002 or other central processing units.

The DSP 2002 may be used in various applications such as modulation / demodulation, coding / decoding, interleaving / deinterleaving, spreading / despreading, inverse fast Fourier transform (IFFT) / fast Fourier transform (FFT), cyclic prefix addition / Lt; RTI ID = 0.0 > and / or < / RTI > other signal processing functions. In an embodiment, for example, in a code division multiple access (CDMA) technology application, the DSP 2002 may perform modulation, coding, interleaving, and spreading in the case of a transmitter function, (2002) may perform despreading, deinterleaving, decoding, and demodulation. In another embodiment, for example, in an orthogonal frequency division multiple access (OFDMA) technology application, in the case of a transmitter function, the DSP 2002 may perform modulation, coding, interleaving, inverse fast Fourier transform, The DSP 2002 may perform cyclic prefix removal, fast Fourier transform, deinterleaving, decoding, and demodulation in the case of receiver functions. In other wireless technology applications, other signal processing functions and combinations of signal processing functions may be performed by the DSP 2002.

The DSP 2002 is capable of communicating with the wireless network via the analog baseband processing unit 2010. In some embodiments, communication may provide an Internet connection that enables a user to access content on the Internet and send and receive e-mail or text messages. An input / output interface 2018 interconnects various memory and interfaces with the DSP 2002. The memory 2004 and the removable memory card 2020 may provide software and data for configuring the operation of the DSP 2002. Among the interfaces may be a USB interface 2022 and a short-range wireless communication sub-system 2024. USB interface 2022 may be used to charge client node 1902 and may also enable client node 1902 to function as a personal computer or a peripheral device for exchanging information with other computer systems. The short-range wireless communications subsystem 2024 may include an infrared port, a Bluetooth interface, an IEEE 802.11 compliant wireless interface, or any other short-range wireless communications sub-system, And wirelessly with the access nodes.

The input / output interface 2018 may further couple an alert 2026 DSP 2002 that, when triggered, causes the client node 1902 to provide notification to the user, for example, by ringing, playing a melody, It will be possible. The alert 2026 may be triggered by silent vibration of any of several events, such as an incoming call, a new text message, and an appointment reminder, or by playing a particular pre-assigned melody against a particular caller By doing so, it will be able to serve as a mechanism to warn the user.

The keypad 2028 is connected to the DSP 2002 and the I / O interface 2018 via the I / O interface 2018 to provide a mechanism for the user to make choices, enter information, and otherwise provide input to the client node 1902 Lt; / RTI > The keyboard 2028 may be a reduced or full size alphanumeric keyboard such as the QWERTY, Dvorak, AZERTY, and sequence keyboard types, or it may be a conventional numeric keypad with alphabetic characters associated with the telephone keypad. The input keys may also include a track wheel, an exit or escape key, a trackball, and other steerable or function keys that can be pressed inward to provide additional input functionality. Another input mechanism may be the LCD 2030, which may include a touch screen function and also display text and / or graphics to the user. The LCD controller 2032 couples the DSP 2002 with the LCD 2030.

When a CCD camera 2034 is mounted, such a CCD camera 2034 enables the client node 1902 to take digital photographs. The DSP 2002 communicates with the CCD camera 2034 via a camera controller 2036. [ In another embodiment, CCD cameras and cameras operating according to other techniques may be used. A GPS sensor 2038 can be coupled to the DSP 2002 for decoding satellite navigation system (GPS) signals or other navigation signals, thereby allowing the client node 1902 to determine its location. Various other peripherals may be further included to provide additional functions such as radio and television reception.

Figure 21 shows a software environment 2002 that may be implemented by a digital signal processor (DSP). In this embodiment, the DSP 2002 shown in Fig. 20 executes an operation system 2104 that provides a platform on which the remaining software operates. Similarly, operating system 2104 provides client node 1902 hardware with standardized interfaces (e.g., drivers) that are accessible to application software. Similarly, the operating system 2104 includes an application management service (AMS) 2106 that communicates control between applications running on the client node 1902. Also shown in FIG. 21 are a web browser application 2108, a media player application 2110, and Java applets 2112. The web browser application 2108 configures the client node 1902 to act as a web browser so that the user can enter information in forms and retrieve and view web pages Allows you to select links. The media player application 2110 configures the client node 1902 to retrieve and play back audio and audiovisual media. The Java applets 2112 configure the client node 1902 to provide games, utilities, and other functions. Component 2114 may provide the functionality described herein. In various embodiments, the client node 1902, the wireless network node 1908, and the server node 1916 shown in FIG. 19 similarly include processing elements Lt; / RTI >

As used herein, the terms "component," "system," and the like are intended to refer to a computer-related entity of one of hardware, software, a combination of hardware and software, software, . For example, an element may be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, or a computer. Describing this, both the application running on the computer and the computer itself can be components. One or more components may reside in the thread of a process or run and the components may be confined to one computer or distributed to two or more computers.

Similarly, as used herein, the term "node " broadly refers to a connection point, such as a redistribution point or a communication endpoint, of a communication environment such as a network. Thus, such nodes refer to active electronic devices capable of transmitting, receiving, or forwarding information over a communication channel. Examples of such nodes include data circuit-terminating equipment (DCE), such as a modem, hub, bridge or switch, and a handset, printer or host computer (e.g., a router, Or a data terminal equipment (DTE) such as a server). Examples of local area network (LAN) or wide area network (WAN) nodes include computers, packet switches, cable modems, data subscriber line (DSL) modems, and wireless LAN (WLAN) ). Examples of Internet or Intranet nodes include host computers, bridges, and WLAN access points identified by IP (internet protocol) addresses. Similarly, examples of nodes in cellular communications include base stations, relays, base station controllers, home location registers, Gateway GPRS Support Nodes (GGSN), and Serving GPRS Support Nodes (SGSN) .

Other examples of nodes include client nodes, server nodes, peer nodes, and access nodes. As used herein, a client node may be a mobile node, a smart phone, a personal digital assistants (PDAs), handheld devices, portable computers, tablet computers, and similar devices, or other May refer to wireless devices such as user equipment (UE). Similarly, such client nodes may refer to mobile, wireless devices, or, conversely, may refer to devices having similar performance that can not normally be moved, such as desktop computers, set top boxes, or sensors will be. Similarly, as used herein, server nodes refer to an information processing device (e.g., a host computer), or a set of information processing devices, that perform information processing requests submitted by other nodes. Similarly, as used herein, a peer node may occasionally operate as a client node and be able to serve as a server node at other times. In a peer-to-peer or overlay network, a node that actively routes data to other networked devices as well as the node itself is referred to as a supernode It will be possible.

As used herein, an access node refers to a node that provides client node access to a communication environment. Examples of access nodes include cellular network base stations and wireless broadband (e.g., WiFi, WiMAX, etc.) access points, which provide corresponding cell and WLAN coverage areas. As used herein, a macrocell is generally used to describe a traditional cellular network cell coverage area. Such macro cells are typically found in rural areas, along highways, or in densely populated areas. Similarly, as used herein, a microcell refers to a cellular network cell having a coverage area that is less than the coverage area of the macrocell. Such microcells are typically used in densely populated urban areas. Similarly, as used herein, a picocell refers to a cellular network coverage area that is less than the coverage area of a microcell. An example of a coverage area of a picocell is a large office, a shopping mall, or a train station. As used herein, a femtocell refers to the smallest commonly accepted area of cellular network coverage currently. By way of example, the coverage area of a femtocell is sufficient for homes or small offices.

Generally, a coverage area of less than two kilometers typically corresponds to a microcell, corresponds to a picocell for less than 200 meters, and corresponds to a femtocell for approximately 10 meters. Similarly, as used herein, a client node communicating with an access node associated with a macrocell is referred to as a "macrocell client ". Similarly, a client node communicating with an access node associated with a microcell, picocell, or femtocell is referred to as a "microcell client "," picocell client ", or "femtocell client ", respectively.

Although the exemplary embodiments disclosed herein have been described with reference to specific exemplary embodiments, it is to be understood that the disclosure is not limited to the examples set forth herein, which illustrate aspects of the present disclosure that may be applied to a wide variety of authentication algorithms The present invention is not necessarily limited to these embodiments. Accordingly, the specific embodiments described above are merely for illustrative purposes and should not be construed as limitations on the disclosure herein, which is not intended to limit the scope of the present invention to those skilled in the art having the benefit of the teachings herein, Because it can be modified and implemented. Accordingly, the foregoing description is not intended to limit the invention to the particular forms disclosed, but on the contrary, it is intended to cover alternatives, modifications and variations, as may be included within the spirit and scope of the invention as defined by the appended claims. It will be understood by those skilled in the art that various changes, substitutions, and substitutions may be made therein without departing from the spirit and scope of the broadest aspect of the invention.

Claims (61)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete CLAIMS What is claimed is: 1. A method of configuring a feedback scheme to work with co-ordinated multiple-point (CoMP) transmissions in a wireless system having a plurality of transmission points,
To support feedback of an RI report including a common rank indicator (RI) for all transmission points at the plurality of transmission points and one of the individual RIs for each of the plurality of transmission points, ≪ / RTI >
Configuring the wireless device to support feedback of a separate Precoding Matrix Indicator (PMI) report for each of the plurality of transmission points; And
At least one of a separate Channel Quality Indicator (CQI) report for each of the plurality of transmission points, a common CQI report for all of the plurality of transmission points, and a separate CQI report and a common CQI report Steps to define
;
A plurality of reports including the RI report, the individual CQI / PMI reports, and the common CQI report are fed back to the Node B via a single transmission point selected from the plurality of transmission points,
The plurality of reports may include at least one report transmitted via a Physical Uplink Control Channel (PUCCH), and at least one report transmitted via a Physical Uplink Shared Channel (PUSCH) At least one of the RI report, the PMI reports and the individual CQI reports and the common CQI report are transmitted on the PUCCH and the RI report, the PMI reports and the individual CQI report And wherein the common CQI report is transmitted on the PUSCH. 28. The method of claim 27,
Transmitting the plurality of reports via at least one of the PUCCH and the PUSCH,
The plurality of reports include:
An RI report including a common RI for all of the plurality of transmission points or one of the individual RIs for each of the plurality of transmission points,
Each of the plurality of transmission points, and separate PMI reports for each of the plurality of transmission points and at least one of the common CQI reports for each of the plurality of transmission points,
Lt; / RTI >
When at least one of the RI report, the PMI reports, and the respective CQI reports and the common CQI report are transmitted on the PUCCH, different reports from different transmission points are time- Division multiplexed (TDM) scheme is transmitted on the PUCCH in different subframes. 28. The method of claim 27,
Wherein individual RIs for each of the plurality of transmission points are jointly encoded and transmitted together in the same RI report fed back to the Node B. 28. The method of claim 27,
Further comprising extending the feedback modes to report feedback on at least one of a PUCCH and a PUSCH for closed-loop transmission, wherein the extended feedback modes comprise 3GPP Release 8 feedback modes < RTI ID = 0.0 > 1-1, 2-1, and modes 3-1, 1-2 and 2-2 for feedback on the PUSCH. 28. The method of claim 27,
Further comprising extending the feedback modes to report feedback on at least one of the PUCCH and PUSCH feedback modes for open-loop transmission, wherein the extended feedback modes comprise 3GPP Release 8 feedback modes 1 for feedback on the PUCCH -0, 2-0, and modes 2-0, 3-0 and 2-2 for feedback on the PUSCH. 31. The method of claim 30,
Wherein the joint CQI reports are derive and fed back for at least one of the extended feedback modes. 31. The method of claim 30,
Wherein feedback reports for different TPs (transmission points) are transmitted in an alternating manner within different sub-frames within the extended PUCCH feedback modes. 31. The method of claim 30,
Wherein feedback reports of the same type for different TPs are combined and transmitted in the same report in the extended PUCCH feedback modes. 33. The method of claim 32,
When the wireless device is configured to select a set of highest M sub-bands for reporting feedback of transmissions from transmission points corresponding to the selected sub-bands, the selection of the highest-M sub- Is based on a joint CQI from the plurality of transmission points, rather than a separate CQI for a transmission point of the plurality of transmission points. 36. The method of claim 35,
For the selected sub-band reporting, the UE derives individual CQI / PMI reporting for each transmission point based on the selected sub-bands and assumes a feedback, an individual transmission from each transmission point, Gt; a < / RTI > feedback scheme. 37. The method of claim 36,
For the selected sub-band reporting, the UE derives joint CQIs for each selected sub-band by assuming a joint transmission from all participating transmission points, and feedback . delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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