CN112400347A - Transmission techniques for wireless communication systems - Google Patents

Abstract

A method of wireless transmission between a base station (gNB) and a group of User Equipments (UEs) 1-UE4 is provided. The base station transmits (102) a message group of Downlink Control Information (DCI) on a downlink control channel to the group of user equipments. The message set includes a downlink control information set indicating at least a first user equipment and a second user equipment in the user equipment set are scheduled to receive data transmissions on a downlink data channel. The base station sends (103) a first data transmission to the first user equipment according to the downlink control information group on the downlink data channel. The base station sends (103) a second data transmission to the second user equipment according to the downlink control information group on the downlink data channel. The first data transmission and the second data transmission are spatially multiplexed.

Description

Transmission techniques for wireless communication systems

Technical Field

The present application relates to transmission techniques for wireless communication systems.

Background

Wireless communication systems, such as third generation (3G) mobile telephone standards and techniques are well known. Such 3G standards and techniques are set by the third generation partnership project (3 GPP). Third generation wireless communications are commonly used to support macrocell mobile telephone communications and are constantly evolving. Communication systems and networks have evolved towards broadband and mobile systems.

In a cellular wireless communication system, User Equipment (UE) is connected to a Radio Access Network (RAN) over a radio link. The RAN comprises a set of base stations and an interface to a Core Network (CN). The base station provides a radio link for UEs located in a cell covered by the base station. The CN provides overall network control. It will be readily appreciated that the RAN and CN each perform functions related to the overall network. For convenience, the term "cellular network" will be used herein to refer to the combination of the RAN and the CN. It is to be understood that the term is used to refer to the respective system performing the disclosed function.

The 3GPP has developed a so-called Long Term Evolution (LTE) system, the evolved universal mobile telecommunications system, the terrestrial radio access network (E-UTRAN). The LTE is used to implement a mobile access network in which one or more macro cells are supported by base stations called enodebs or enbs (evolved nodebs). Recently, LTE is further evolving towards so-called 5G or NR (new radio) systems, where one or more cells are supported by a base station called a gNB. NR is intended to use an Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

One purpose of the 5G system is: super-connectivity is supported by allowing a large number of different types of devices to access a 5G network, for example 100 ten thousand connections per square kilometer. Thus, one 5G cell may serve thousands of UEs. Furthermore, it is also envisioned that a multi-layer layout will occur. Where macro cells may provide coverage and small cells provide high throughput. To guarantee a minimum quality of service (QoS) for each device, the gNB must be able to transmit and receive data for each device within a limited time. However, it is difficult to achieve such QoS with limited time-frequency resources. Most transmissions in the uplink or downlink require signaling of control information to the UE to indicate which time-frequency resources to utilize for reception or transmission.

One solution to achieve this is by creating small cells with carrier frequencies in the millimeter wave band (30GHz to 300 GHz). In these higher frequency bands, more spectrum is available. Thus, more resources are available for control signaling, which in turn can be used to serve more UEs. However, the number of users may increase more than the additional resources. Therefore, supporting numerous low power devices is a challenge.

Another solution is to allocate the same time-frequency resources to multiple users. This transmission scheme is referred to as multi-user multiple-input multiple-output MIMO (MU-MIMO). Interference between users can be mitigated by appropriate precoding on the gbb and by interference cancellation on the UE. One problem with this scheme is the need to find a set of users whose data reception and channel conditions allow MU-MIMO to be applied.

As the number of users increases, there is more opportunity to apply MU-MIMO. Therefore, MU-MIMO benefits from a large number of connected users, known as MU diversity. While MU-MIMO has the potential to improve spectral efficiency by multiplexing multiple users on the same time-frequency resource, there is still a need to schedule data transmission for each UE through transmission of control information.

One of the problems in data transmission is control blocking. The system may have capacity on the data channel for data scheduling, but not enough resources on the control channel for data scheduling. The control channels in a 5G system are referred to as control resource sets (CORESET). Therefore, not all data may be scheduled within one Transmission Time Interval (TTI).

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the subject matter of the disclosure, nor is it intended to be used to identify the scope of the disclosure.

The present application provides a method of wireless transmission between a base station and a group of User Equipments (UEs), the method performed at the base station, comprising: transmitting a set of Downlink Control Information (DCI) messages on a Downlink Control channel to the set of user equipments, the set of messages including a set of Downlink Control Information indicating at least a first user equipment and a second user equipment in the set of user equipments scheduled to receive data transmissions on a Downlink data channel; transmitting a first data transmission to the first user equipment on the downlink data channel in accordance with the downlink control information set; transmitting a second data transmission to the second user equipment on the downlink data channel according to the downlink control information group, wherein the first and second data transmissions are spatially multiplexed.

In some embodiments, the set of downlink control information comprises a bitmap; the bitmap indicates which user equipments in the group of user equipments are scheduled to receive data transmissions on the downlink data channel.

In some embodiments, the method comprises transmitting information to one of the group of user equipment to indicate an association between the user equipment and a digit position in the bitmap.

In some embodiments, the method comprises transmitting the information to indicate an association when the user equipment is configured to the group of user equipment.

In some embodiments, the set of downlink control information includes a Radio Network Temporary Identifier (RNTI) scheduled to each user equipment receiving data transmissions on the downlink data channel.

In some embodiments, the method comprises transmitting an indication of a Modulation and Coding Scheme (MCS) of the scheduled user equipment.

In some embodiments, said indication of a transmission modulation and coding scheme comprises transmitting a base MCS value and transmitting a difference value for at least one other said scheduled user equipment.

In some embodiments, the indication of the transmission modulation and coding scheme comprises one of:

transmitting a basic MCS value for one of the scheduled user equipments and a difference value for each of the other scheduled user equipments; transmitting a basic MCS value and a difference value for each of the scheduled user equipments.

In some embodiments, the method comprises transmitting an indication of at least one of the following resource allocations: allocating time resources; frequency resource allocation for each scheduled user equipment.

In some embodiments, the method comprises transmitting a base value and a difference value for each scheduled user equipment to transmit at least one of the following resource allocations: allocating time resources; frequency resource allocation for each of the scheduled user equipments.

In some embodiments, the method comprises transmitting an indication of antenna ports for at least one scheduled user equipment. Optionally, an indication of the antenna port is transmitted for each scheduled UE.

In some embodiments, the method comprises assigning one user equipment to the group of user equipments. The user equipment is not currently part of the user equipment of the group.

In some embodiments, the message of downlink control information is encoded by one or more of: a Radio Network Temporary Identifier (RNTI) specific to the downlink control information group; a group identification of the downlink control information group; resource allocation specific to the downlink control information group.

In some embodiments, the method comprises sending to the user equipment one or more of: a Radio Network Temporary Identifier (RNTI) specific to the downlink control information group; a group identification of the downlink control information group; resource allocation specific to the downlink control information group.

In some embodiments, each of the spatially multiplexed transmissions uses the same set of overlapping time-frequency resources. The sets of resources may be fully overlapping or partially overlapping.

In some embodiments, the downlink control information group indicates a third user equipment in the user equipment group; the third user equipment is scheduled to receive a data transmission on the downlink data channel; the method further comprises sending a data transmission to the third user equipment on the downlink data channel in accordance with the downlink control information group; wherein data transmissions sent to the third user equipment are not spatially multiplexed with data transmissions sent to other invoked user equipment.

The present application provides a method for wireless transmission between a base station and a User Equipment (UE), the method being performed at the UE and comprising: receiving a message group of Downlink Control Information (DCI) on a Downlink Control channel; the message group comprises a downlink control information group indicating at least a first user equipment and a second user equipment in a group of user equipments scheduled to receive data transmissions on a downlink data channel; determining from the downlink control information set whether the user equipment is scheduled to receive a data transmission, if the user equipment is scheduled to receive a data transmission, receiving a first data transmission at the user equipment on the downlink data channel according to the downlink control information set; wherein the first data transmission and a second data transmission of another scheduled user equipment are spatially multiplexed.

The present application provides a method of wireless transmission between a base station and a group of User Equipments (UEs), the method performed at the base station, comprising: transmitting a message group of Downlink Control Information (DCI) to the user equipment group on a Downlink Control channel; the message group comprises a downlink control information group indicating at least a first user equipment and a second user equipment in the user equipment group scheduled to receive data transmissions on a downlink data channel; transmitting a message of first downlink control information to the first user equipment on the downlink data channel; and sending a message of second downlink control information to the second user equipment on the downlink data channel; wherein the message of the first downlink control information and the message of the second downlink control information are spatially multiplexed.

In some embodiments, the set of downlink control information comprises a bitmap; the bitmap indicates which user equipments in the group of user equipments are scheduled to receive user equipment specific messages on the downlink data channel.

In some embodiments, the method comprises transmitting information to one of the group of user equipment to indicate an association between the user equipment and a digit position in the bitmap.

In some embodiments, the method comprises transmitting the information to indicate an association when the user equipment is assigned to the group of user equipment.

In some embodiments, the set of downlink control information includes an index to a parameter table to receive a user equipment specific message of the downlink control information.

In some embodiments, the parameter table indicates one or more of: modulation and Coding Scheme (MCS); allocating time resources; and allocating frequency resources.

In some embodiments, the method includes transmitting the parameter table to the ue through upper layer signaling, optionally through Radio Resource Control (RRC) signaling.

In some embodiments, the user equipment specific parameter for indicating a frequency resource allocation is a size of the frequency resource allocation; the downlink control information group further includes an indication of a frequency resource allocation for a group scheduling message.

In some embodiments, the user equipment specific message of downlink control information comprises a plurality of repetitions of user equipment specific downlink control information.

In some embodiments, the method comprises transmitting an indication of a number of repetitions of said downlink control information specific to a user equipment to at least one of said user equipments.

In some embodiments, the multiple repetitions of the user equipment specific downlink control information are encoded with at least two different redundancy versions.

In some embodiments, the indication of the sequence of redundancy versions is transmitted to the scheduled user equipment. It may be transmitted as part of the setup information, i.e. by upper layer signaling.

The present application provides a method for wireless transmission between a base station and a User Equipment (UE), the method being performed at the UE and comprising: receiving a message group of Downlink Control Information (DCI) on a Downlink Control channel; the message group comprises a downlink control information group indicating at least a first user equipment and a second user equipment in a user equipment group scheduled to receive data transmissions on a downlink data channel; determining from the downlink control information group whether the user equipment is scheduled to receive a message of downlink control information, if the user equipment is scheduled to receive a message of downlink control information, receiving a message of first downlink control information at the user equipment according to the downlink control information group on the downlink data channel; wherein the message of the first downlink control information and the message of the second downlink control information transmitted to another scheduled user equipment are spatially multiplexed.

The present application provides a method for wireless transmission between a base station, a first User Equipment (UE), and a second UE, wherein the method is performed at the base station, and comprises: transmitting a first Downlink Control Information (DCI) message to the first user equipment on a Downlink Control channel, the DCI message including first Downlink Control Information of the first user equipment; and transmitting a message of second downlink control information to the second user equipment on the downlink control channel, the message of second downlink control information including second downlink control information of the second user equipment; wherein the message of the first downlink control information and the message of the second downlink control information are spatially multiplexed.

In some embodiments, the first downlink control information is for scheduling data transmission to the first user equipment; the method comprises the following steps: and transmitting first data to the first user equipment on the downlink data channel according to the first downlink control information.

In some embodiments, the method comprises transmitting a control channel definition comprising an antenna port setting table to allow the first user equipment to receive the first downlink control information.

In some embodiments, the method includes transmitting an antenna port setting, the setting being an index to the antenna port setting table.

In some embodiments, the method comprises receiving antenna port capabilities from the first user equipment and receiving antenna port capabilities from the second user equipment.

The present application relates to a method for wireless transmission between a base station and a first User Equipment (UE), the method being performed at the first UE, and includes: receiving setting information to set user equipment to receive control information of a downlink control channel through antenna port setting; and receiving a first Downlink Control Information (DCI) message on the Downlink Control channel using an antenna port; the message of the first downlink control information comprises first downlink control information of the first user equipment; wherein the message of the first downlink control information and the message of the second downlink control information transmitted to the second user equipment are spatially multiplexed.

In some embodiments, the setting information includes an antenna port setting table and an antenna port setting, and the antenna port setting is an index of the antenna port setting table.

A large-dimensional MIMO antenna array can produce multiple sharp beams, thereby spatially separating the users. These beams may reduce interference from co-scheduled UEs. Thus, quasi-orthogonal users can be served simultaneously using the same time-frequency resources.

An advantage of at least one example is that by spatially multiplexing (e.g., multiple DCIs) control information in a MU-MIMO like manner, the control overhead of high-load cells is reduced.

Users may be grouped according to the likelihood of co-scheduling on the same PDSCH resources in MU-MIMO transmission. The packets are configured by upper layers, each group having a unique RNTI, e.g., MU-RNTI. The UE may monitor DCI scrambled with MU-RNTI in the configured PDCCH search space.

In one example, a DCI group exists. The DCI group may indicate a resource, an antenna port configuration, and an MCS. The DCI group may include PDSCH configurations for each UE.

In one example, the control information is spatially multiplexed on the data channel PDSCH. Control information is transmitted on the PDSCH instead of data scheduling.

In one example, the DCI is spatially multiplexed on a control channel PDCCH. CORESET can configure different antenna port configurations, so that transmitted DCI can be effectively spatially multiplexed.

An advantage of at least one example is that more UEs are allowed to share the same transmission resource. By allowing control information to efficiently utilize overlapping resources, control congestion is reduced and transmission resources can be more efficiently utilized.

The present application also provides apparatus for performing any of the methods described herein.

Drawings

The details, aspects and embodiments of the present application will be described, by way of example only, with reference to the accompanying drawings. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Similar reference numerals have been included in the various drawings to facilitate understanding.

Fig. 1 shows a wireless communication system.

Fig. 2 shows resources in a communication system.

Fig. 3 illustrates an example method performed by a base station in a system.

Fig. 4 illustrates an example method performed by a wireless device.

Fig. 5A and 5B show an example of resource allocation.

Fig. 6 shows one example of DCI with a bitmap to indicate scheduled UEs.

Fig. 7 shows one example of DCI with an RNTI list to indicate a scheduled UE.

Fig. 8 shows an antenna port value table.

Fig. 9 shows an example of resource allocation.

Fig. 10 illustrates an example method performed by a base station in a system.

Fig. 11 illustrates an example method performed by a wireless device.

Fig. 12 illustrates resources for spatially multiplexing control information in a communication system.

Fig. 13 shows data received/stored at one UE.

Fig. 14 illustrates an example method performed by a base station in a system.

Fig. 15 illustrates an example method performed by a wireless device.

Fig. 16 illustrates an example apparatus at a base station or UE.

Detailed Description

Those skilled in the art will recognize and appreciate that the specific details of the examples described are merely illustrative of some embodiments and that the teachings set forth herein are applicable in a variety of alternative contexts.

Fig. 1 shows one example of a wireless communication system having a wireless base station 10 (e.g., wireless base station gNB) and a plurality of wireless devices UE1, UE2, UE3, UE 4. The number of wireless devices may be smaller than shown in fig. 1, or larger. A wireless device may be referred to as a User Equipment (UE) or a terminal. A base station supports communication with multiple UEs on Downlink (DL) channels and Uplink (UL) channels. The downlink channels include a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Shared Channel (PDSCH). These are all physical layer channels. The PDCCH is one control channel. The PDSCH is a data channel and can be shared by multiple UEs. To transmit data from one base station gNB to one UE, the base station schedules one transmission to one UE. The gNB transmits a Downlink Control Information (DCI) message on the PDCCH. The DCI indicates where (in terms of time and frequency resources) downlink data is to be transmitted. The gbb transmits downlink data on the PDSCH. The PDCCH and PDSCH may be implemented as separate regions in frequency and time within the same time slot. Wherein the PDCCH precedes the PDSCH.

The base station gNB supports multi-user multiple-input multiple-output MIMO (MU-MIMO) communications. This is a spatial multiplexing communication technique for multiple users. A certain number of time-frequency resources are used to simultaneously support communication with multiple users. The base station gbb is provided with a plurality of antennas. Each UE is provided with one or more antennas. For each user, the base station transmits multiple transport streams to the user. The individual streams may be precoded. The base station gNB may form directional beams towards each user to improve the directionality of the transmissions and to improve the spatial separation between transmissions to each user UE1, UE2, UE3, UE 4.

Fig. 2 shows radio resources of a communication system. The frame structure is similar to conventional LTE. The resource comprises a frequency-time grid. A multi-carrier OFDM transmission scheme is employed. An OFDM symbol is transmitted on a set of frequency subcarriers. Fig. 2 shows one time slot in the time domain. There are multiple time slots in the time domain. In a time slot, various channels are transmitted. A control resource set (CORESET) is transmitted during a time slot, typically at the beginning of the time slot. The time slot also includes one data channel PDSCH. Fig. 2 shows one possible region where the PDSCH is located. The PDSCH may occupy different regions in frequency and time.

User grouping

The gNB transmits a Downlink Control Information (DCI) message on the PDCCH. The DCI information is transmitted in a control resource set (CORESET). The DCI indicates a transmission position of downlink data in frequency and time. In the conventional art, one DCI carries information of a single wireless device. In an example of the present application, the DCI carries information of a plurality of wireless devices. This will be referred to as a DCI group, or multi-user DCI (MU-DCI). Multiple wireless devices are grouped so they can be served by the same MU-DCI. For example, in fig. 1, the group may include UE1-UE 4. The group of wireless devices UE1-UE4 receive the same MU-DCI and therefore the same control information, thereby reducing the overall amount of control information transmitted in each slot.

There are various methods of identifying components. These methods include:

1. a group-specific Radio Network Temporary Identifier (RNTI).

2. The group ID.

3. Group-specific resource allocation.

The base station gNB informs the wireless device which group to belong to. This may be achieved by upper layer signaling. For the example of group-specific RNTI, a DCI group may be encoded with an RNTI value (e.g., 0x 6362). The UEs of the group are informed that the group RNTI value is 0x 6362. Subsequently, the UE monitors its assigned CORESET to obtain DCI encoded (scrambled) using the set of RNTIs. With regard to the selection of the group ID, the group ID may be an identifier (e.g., a number) that may be used to identify the messages of the group. The group ID may be included in the DCI message. With regard to the selection of group-specific resource allocations, a dedicated CORESET allocation may be provided for a group of users, and only members of the group are configured to search for DCI for the CORESET. Thus, the group of users is identified by this CORESET. The CORESET has a CORESET id, so that the CORESET id can identify the group.

Generic DCI for MU-MIMO scheduling

In this regard, a DCI group may schedule spatial multiplexing of a plurality of wireless devices. Referring again to fig. 2, the DCI group transmitted in CORESET (MU-DCI) schedules MU-MIMO transmissions for a group of wireless devices on PDSCH. Instead of transmitting N DCIs to schedule MU-MIMO for N users, one MU-DCI schedules data transmission for N users. The MU-DCI schedules data transmission in time-frequency resource blocks 20 on the data channel PDSCH. A DCI group (MU-DCI) may be encoded with a group-specific RNTI to schedule MU-MIMO transmissions on the PDSCH.

Fig. 3 illustrates an example method performed by a base station. At block 101, a base station transmits to a UE (or UEs) to assign the UEs to a group. This may be through upper layer signaling, as described above. The UE may be provided with a group-specific RNTI or some other way of identifying the DCI group. At block 102, the base station transmits a message group of DCI on a downlink control channel to the group of UEs. The message group of the DCI includes a DCI group indicating which UEs in the group are scheduled to receive data transmissions on a downlink data channel. At block 103, the base station transmits data to the intended UE. This may include transmitting a first data transmission to a first UE according to the DCI group on the downlink data channel and transmitting a second data transmission to a second UE according to the DCI group on the downlink data channel. The first data transmission and the second data transmission are spatially multiplexed. The first data transmission and the second data transmission may occupy the same or at least partially overlapping time-frequency resources. At block 104, the base station transmits to a UE (or UEs) to remove the UE from the group.

Fig. 4 illustrates an example method performed by a wireless device UE. At block 111, the UE receives control information to assign the UE to one of the groups. As described above, this may be achieved by upper layer signaling. The UE may be provided with a group-specific RNTI or some other way of identifying the DCI group. At block 112, the UE receives a message group of DCI on a downlink control channel. The message group of the DCI includes a DCI group indicating which UEs in the group are scheduled to receive data transmissions on a downlink data channel. The UE determines whether it is one of the scheduled UEs. If the UE is one of the scheduled UEs, then the UE receives data at block 113. At block 114, the UE receives control information to remove the UE from the group.

Fig. 5A and 5B show two possible examples of resource allocation. A set of DCI is associated with four wireless devices UE1, UE2, UE3, UE 4. One time-frequency resource block 20 includes Physical Resource Blocks (PRBs) 1-18. In fig. 5A, time-frequency resource blocks 20 are allocated to each device. That is, the entire contents of the block 20 are used by each device. The UE1 uses the PRB0-17, the UE2 uses the PRB0-17, the UE3 uses the PRB0-17, and the UE4 uses the PRB 0-17. Spatial multiplexing allows for separate transmissions on each of the UEs 1-4. In FIG. 5B, one time-frequency resource block 20 is allocated to device UE1-UE 4. There is a partial overlap between the resources allocated to each wireless device UE1-UE 4. The PRBs allocated to the device UE1 are 0-17; the PRB allocated to the equipment UE2 is 12-17; the PRB allocated to the equipment UE3 is 6-17; the PRBs allocated by the device UE4 are 0-5. The amount of resources allocated to each device may be selected based on factors such as the size of the payload (i.e., transport block) and channel conditions (MCS).

The existing DCI (Format1_1) can be modified to achieve compact scheduling and trade-off between control information overhead and scheduling flexibility. On the UE side, in order to perform efficient channel estimation for data demodulation, demodulation reference signals (DMRSs) associated with the PDSCH of the UE need to be orthogonal in co-scheduled users. In this way, UE transparent precoding can be achieved, reducing or preventing interference between DMRSs/data of different users. Therefore, it is necessary to inform each UE of the data demodulation antenna ports that must be used.

The MU-DCI indicates which device (UE1-UE4) in the group is scheduled for data transmission in each transmission period. The signaling to the device may include a bitmap or a list of RNTIs.

Bitmap

The MU-DCI includes a bitmap. Each bitmap corresponds to one user in the group. Each device UE is informed which bit of the bitmap is allocated to that device. FIG. 6 shows a bitmap of a UE1-UE4 device group. The first bitmap position is associated with UE1, the second bitmap position is associated with UE2, and so on. Other associations are also possible. In this example, the bitmap indicates that data transmissions are scheduled to device UE1, UE3, and UE 4. The association of a device with a bitmap position can be signaled by upper layer signaling, e.g., signaling that the device UE is assigned to a group in the UE grouping phase. The bitmap provides the UE with information about whether it is scheduled for transmission, how many UEs are co-scheduled, and to which any user specific parameters in the DCI are associated, e.g., antenna ports. Advantageously, the size of the groups is limited to a maximum number to limit the amount of control overhead.

RNTI List

The MU-DCI consists of a list of RNTIs to identify the UE. This approach requires a larger number of bits in the DCI if the user pool is smaller. But this approach may also be advantageous if the number of users in a group is large. Fig. 7 shows an example of DCI with an RNTI list. In this example, the list indicates that data transmissions are scheduled to devices UE1, UE3, and UE 4. One advantage of this scheme is that no additional signaling is needed to associate the device into a bit position before transmission, since the UE already knows the RNTI. The first RNTI in the list may be defined to correspond to the first entry in the list of user-specific parameters in the DCI.

The two techniques described above may be used to transmit UE-specific parameters in DCI. The UE-specific parameters include: an antenna port; MCS; and (4) resource allocation. Each of which will now be described.

UE-specific antenna ports

MU-MIMO transmission requires one antenna port configuration. One way to communicate antenna ports is to set up a list of antenna port configurations, one for each UE. Some of the information in the list may be redundant. For example, refer to the antenna port configuration table in fig. 8, which is taken from TS 38.212. If only one codeword is enabled and a maximum of 4 antenna ports are used, the list shows what value is transmitted for the parameter antenna port(s) in the DCI. For example:

a value of 0 indicates that the UE demodulates PDSCH using antenna port 0, and it can be considered that there is no transmission on antenna port 1;

a value of 1 indicates that the UE demodulates PDSCH using antenna port 1, and it can be considered that there is no transmission on antenna port 0;

a value of 2 indicates that the data is transmitted with two antenna ports of 0 and 1, indicating spatial multiplexing;

a value of 3 indicates that antenna port 0 is used, but other antenna ports may also be in use (for other UEs, such as MU-MIMO), etc.;

a value of 11 indicates that the UE uses antenna ports 0 and 2, but antenna ports 1 and 3 may be used by other UEs.

There are other tables for 2 codewords and/or more supported antenna ports.

To schedule 3 UEs (UE1-UE3), the DCI may contain the list {7,5,6}, i.e., UE1 uses antenna ports 0 and 1, UE2 uses antenna port 2, and UE3 uses antenna port 3.

To schedule 4 UEs (UE1-UE4), the DCI may contain a {3,4,5,6} list, i.e., UE1 uses antenna port 0, UE2 uses antenna port 1, UE3 uses antenna port 2, UE4 uses antenna port 3, assuming all UEs are configured to use the same table. In this example, the last antenna port does not need to be signaled in this case, since the number of scheduled UEs is already known from the bitmap or RNTI list.

The present application may also be preconfigured by conventions known to the base station and the UEs, i.e. fixing the antenna port of each UE. One possible convention is that a first UE always uses antenna port 0 (or multiple antenna ports), a second UE always uses antenna port 1 (or multiple antenna ports), and so on. Such a convention would eliminate the need for explicit signaling.

UE-specific Modulation and Coding Scheme (MCS)

In the case where the MCS is the same for all scheduled UEs within a group, it is not necessary to signal the MCS for each UE. However, this may not be ideal (e.g., if the UE experiences a different SINR). If an MCS signal needs to be signaled for each UE, the simplest scheme is to signal an MCS value for each UE. Which MCS belongs to which UE may be signaled by the gNB before transmission, or may follow a convention (first UE being the first value in the MCS value list, second UE being the second value in the MCS value list, etc.). If a bitmap is used for user selection, the position of the bit may be used as an indication of which MCS to use. For example, the highest '1' bit (MSB) corresponds to the first MCS, and so on.

Another option to reduce the signaling overhead is to signal a differential MCS, i.e. to signal the difference between the MCS value of the second UE and the MCS value of the first UE. This requires a base MCS value and a small, low resolution deltaMCS signal for each UE. For example, the MCS value in the DCI is 5 bits. Thus, a signal may be selected that has a base MCS value of 20, and then 3 bits to represent deltaMCS, 1 bit to represent symbols, and 2 bits to represent differences (deltas). In this example, the signal values are allowed to range from 17 to 23 (20-3; 20-2; 20-1; 20; 20+ 1; 20+ 2; 20+ 3). Another option is to specify the step size. Consider a step size of 4 and a 3-bit deltaMCS (1-bit symbol, 2-bit value). This allows deltaMCS values of +/-0, 4, 8, 12.

In the above example, the base MCS value may be one of an MCS value and a difference value of one scheduled UE. For example, to signal the MCS values UE 1-18, UE 2-19, and UE 3-20, the base MCS value 18 (in this case, the value of UE1) may be transmitted, along with the differences +1, + 1. In another example, the base MCS may not correspond to one of the MCS values of the UE. For example, in order to signal the MCS value UE1 ═ 18, UE2 ═ 19, and UE3 ═ 23, the basic MCS value 20 is transmitted, along with the difference-2 (═ UE1), -1(═ UE2), and +3(═ UE 3). Both the gNB and the UE know which scheme is being used and use the same scheme. This scheme may be selected to minimize the total amount of signaling data to encode all MCS values.

UE-specific resource allocation

The time-frequency resources may be common resources for all UEs in the group or may be allocated for each UE. In the case where each UE allocates resources, it is preferable to reduce the amount of signaling data. The resource allocation may be expressed in terms of UE or difference.

Currently, DCI format1_1 has two fields for scheduling time and frequency resources. One option is to signal only the UE specific time allocation and to reserve the frequency allocation for all UEs in the group, or to signal only the UE specific frequency allocation and to reserve the time allocation for all UEs in the group.

Another option is to use differential signaling. One reference resource allocation is signaled in full. The other resource allocations are then signaled as delta values compared to the resource allocation that has signaled in its entirety, or as delta values compared to the last entry in the delta value list.

Spatial multiplexing control information on PDSCH

In this aspect, the DCI group schedules spatial multiplexing of a plurality of wireless devices. However, unlike the examples described in fig. 3 through 7, the set of DCI schedules spatial multiplexing of control data on a data channel (PDSCH). This frees up resources on the control channel PDCCH. Referring again to fig. 2, one group of DCI transmitted in CORESET (MU-DCI) schedules MU-MIMO transmissions for a group of wireless devices on PDSCH. A single MU-DCI schedules transmission of N user control data. The MU-DCI schedules the transmission of control data in time-frequency resource blocks 20 on the data channel PDSCH. A DCI group (MU-DCI) may be encoded with a group-specific RNTI to schedule MU-MIMO transmissions on the PDSCH.

One advantage of this scheme is that control overhead is reduced. One DCI on the PDCCH is used to schedule N DCIs of N UEs in parallel. Another advantage is flexible offloading of control resources. For example, DCI scheduling DL/UL transmissions for future time slots may be transmitted anywhere in the time slot, e.g., at the end. It should be noted that CORESET is typically assigned at the beginning of a time slot.

The UEDCI may be any kind of DCI. For example, DCI formats 2_0, 2_1, 2_2, and 2_3 are defined in 3 GPPTS38.2.12. These DCIs may also be encoded with UE-specific RNTIs. For example, DCI format 2_0 is a slot format indication scrambled with SFI-RNTI, which may be configured for each UE (or common to multiple UEs). The slot format indicates which OFDM symbols are for UL/DL or indicates unspecified. Another example is DCI format 2_1, which indicates a preset. It is scrambled with INT-RNTI, which is also UE specific. It indicates that some of the DL resources of the UE have been covered by higher priority transmissions and allows the UE to take necessary actions. Each UEDCI may be used to indicate scheduling of data in PDSCH of a subsequent time slot or time unit.

The technique can be used in any MU-MIMO applicable scenario. MU-MIMO is particularly suitable for low mobility scenarios with moderate to good signal-to-noise ratios (SINRs). In general, PDSCH cannot provide the same reliability as PDCCH, and co-scheduling UE will cause some interference. Control information generally requires higher transmission reliability than data, so reliable decoding of control information on PDSCH requires good radio conditions. Control information usually requires very small data packets (e.g., DCI is foreseen as 140 bits in rel.15).

Techniques are presented to optimize MU-DCI overhead. The UE specific parameters in DCI include: an antenna port; MCS; and (4) resource allocation. Each UE antenna port may signal the scheduled UE in the manner described above as "generic DCI for MU-MIMO scheduling".

Discrete combination of decoding parameters

The possible DCI sizes of each ue DCI transmitted on the PDSCH are limited (i.e., the possible sizes are few). The requirement for high reliability of the transmission also requires a lower MCS. The possible combinations of relevant parameters are preferably collected in a table and the index of the entry in the table is included in the MU-DCI. Fig. 8 shows an example of resource allocation per UE dci in UE1-UE 4. The resource allocations are overlapping in time and (at least part of) frequency. The respective resource allocations of UE1-UE4 are displayed side-by-side for improved clarity. It will be appreciated that MU-MIMO transmission will use the same resource block 20 to transmit DCIUE1-DCIUE4 in parallel.

Referring again to fig. 2, the group MCI (MU-DCI) indicates the position of the block 20 in time and frequency. Within this block of resources, the UE will blindly attempt to decode the PDSCH using the possible combinations in the signals in the table. Table 1 is an example table. Each entry is a combination of three values: MCS, frequency resource allocation in PRBs, and time resource allocation in OFDM symbols. For example, a multiple of 6 PRBs may be selected for frequency allocation. This is the same as the Control Channel Element (CCE) size in PDCCH resource allocation.

Index	{ MCS, frequency allocation in PRB, time allocation in OFDM symbol }
		0	{0,6,3},{0,12,3},{1,18,3},{2,18,3}
1	{0,6,3},{0,12,3},{9,18,3},{9,6,2}
		2	{9,18,2},{12,6,2}
3	{12,6,2},{16,6,2}

Table 1-MCS and resource allocation examples for PDSCH decoding

In the example shown in FIG. 9, there is a partial overlap between the resources allocated to each wireless device UE1-UE 4. DCIUE1 has allocated PRBs of 0-17 (18 PRBs total); DCIUE2 has allocated PRBs of 12-17 (6 PRBs total); DCIUE3 has allocated 6-17 PRBs (12 PRBs total); DCIUE4 has allocated PRBs of 0-5 (6 PRBs total). Each resource is allocated 3 OFDM symbols in time. In the example of fig. 9, DCIUE is multiplexed with the attribute of table index 0. The DCI group (MU-DCI) transmitted to the UE indicates an index of 0. The amount of resources allocated to each DCI may depend on one or more of: payload size, coding (MCS, number of repetitions).

In decoding MU-DCI, one UE receives an index specifying the DCIUE attribute and will then try all possible decoding combinations. Index 0 has two entries, and 18 PRBs: {1,18,3},{2,18,3}. This requires one decoding attempt when MCS is 1 and one decoding attempt when MCS is 2. Since the block 20 is 18 PRBs in length, there is no ambiguity in the starting position (in frequency) of the block 20. To limit the number of blind decoding attempts, the starting position of the frequency resource allocation is preferably limited to a multiple of PRBs (e.g., 6 PRBs), starting with the first RE signal in the MU-DCI. The combination 0,6,3 requires three decoding attempts: the first attempt starts with PRB 0; the second attempt starts with PRB 6; the third attempt starts with PRB 12. The combination 0,12,3 requires two decoding attempts: the first attempt starts from PRB0 and the second from PRB 6. Therefore, there are a total of 7 decoding attempts. Since the TB is small, the UE can easily handle this problem.

Furthermore, a plurality of possible tables may also be provided. The gNB signals the UE to tell it which table to use. The signaling of which table to use may be performed by upper layer signaling, e.g., signaling of a configured UE group. The configured table may be the same for all UEs in the group, or at least for the scheduled UEs in the TTI. The plurality of tables may include a table for repetition and a table for a different number of layers. The use of a table helps to reduce the total amount of signalling data in each DCI, since the DCI can simply carry an index. The index refers to an entry in a table stored at the UE.

One table, or the association of one table with one UE, may be semi-statically updated through upper layer signaling. Alternatively, the MU-DCI may be used to send a message (in the form of a special DCI) to all UEs in the group, thereby updating the group configuration.

The DCI group (MU-DCI) described in the above-mentioned "general DCI for MU-MIMO scheduling" may be used in this regard.

Fig. 10 illustrates an example method performed by a base station. At block 201, a base station transmits to a UE (or UEs) to assign the UEs to a group. As described above, it is possible to pass upper layer signaling. The UE may be provided with a group-specific RNTI or some other way of identifying the DCI group. At block 202, the base station transmits a message group of DCI on a downlink control channel to the group of UEs. The message group of DCI includes a group DCI indicating which UEs in the group are scheduled to receive transmission of the UE-specific DCI on the downlink data channel. At block 203, the base station transmits DCI to each of the scheduled UEs. This may include transmitting first DCI on a downlink data channel to a first UE and transmitting second DCI on a downlink data channel to a second UE. The first DCI and the second DCI are spatially multiplexed. The first data transmission and the second data transmission may occupy the same or at least partially overlapping time-frequency resources. At block 204, the base station transmits to a UE (or UEs) to remove the UE from the group.

Fig. 11 illustrates an example method performed by a wireless device UE. At block 211, the UE receives control information to assign the UE to a group. As described above, it is possible to pass upper layer signaling. The UE may be provided with a group-specific RNTI or some other way of identifying the DCI group. At block 212, the UE receives a message group of DCI on a downlink control channel. The message group of the DCI includes a DCI group. The DCI group indicates which UEs in the group are scheduled to receive a transmission of each UE DCI on a downlink data channel. The UE determines whether it is one of the scheduled UEs. If the UE is one of the scheduled UEs, then at block 213 the UE receives the DCI. At block 214, the UE receives control information to remove the UE from the group.

Setting repetition to improve reliability

The coding in PDCCH is designed to: an acceptable BLER can be achieved even at very low signal-to-noise ratios (SNRs). It is difficult to achieve such performance in PDSCH. Therefore, in order to improve reliability of control information on the PDSCH, it is preferable to use data repetition. One possibility is to repeat the control data multiple times before encoding, thereby creating a larger transport block for more reliable encoding. Another possibility is to encode the transport blocks with different Redundancy Versions (RVs) that are concatenated and sent to the UE. The UE may combine the transmissions before attempting decoding. The RV sequence may be predefined, for example, RV: 0123 is 4 repeats or RV: 012301 is 6 replicates. In both cases, the number of repetitions, or at least the maximum number of repetitions, may be signaled to the UE. The number of repetitions may be included in the decoding table. An example table is shown in table 2.

Table 2-MCS and resource allocation examples for PDSCH decoding with repetition

The PDSCH allows multi-layer transmission. Control data for one user may be mapped to multiple layers. The number of layers may also be included in the table.

One way to reduce the amount of control information is to code all the control information on the PDSCH identically. The DCI for each UE is identically encoded using the same MCS. Each DCIUE has the same resource allocation. This only requires signaling of the antenna port to the UE. The signaling may be done through one bitmap and one antenna port configuration list, with the disadvantage that no UE specific link adaptation is applied, so the worst case MCS applies for all UEs. The size of the TB is the same for all UEs, which means that the payload/size of the DCI is also the same.

DCI technique for spatial multiplexing on PDCCH

Typically, the PDCCH is transmitted on a single antenna port in a pre-configured control resource set (CORESET). Spatial multiplexing is not feasible, for the reasons: the PDCCH carrying the control information should be reliably received by all UEs in the cell.

In this regard, CORESET supports spatial multiplexing of DCI on a control channel PDCCH. Fig. 12 shows radio resources of a communication system. CORESET includes DCI for UE1, DCI for UE2, and DCI for UE 3. One wireless device is configured to receive CORESET.

The control information is configured by ControlResourceSet in PDCCH-Config and normal CORESET in PDCCH-ConfigCommon. One parameter, antennaPorts, is added to ControlResourceSet. This is an index into a table of possible antenna port configurations. The table itself can be represented by different parameters, such as antennaPortTable in ControlResourceSet. Thus CORESET can support various antenna port configurations like PDSCH.

The UE configures its UE-specific PDCCH configuration by one RRC message PDCCH-Config (refer to TS 38.331). The PDCCH-Config includes several fields for configuring the core set and search space of the UE. It can be configured with 4 CORESET at most. The configuration of CORESET is specified in the field ControlResourceSet. ControlResourceSet includes all parameters needed to configure one CORESET, such as ID, frequency domain resources, duration, etc.

An additional parameter antennaportTable can be added to ControlResourceSet. The antennaPortTable may be the same as the PDSCH, i.e., as shown in fig. 8. It will be appreciated that the table may have different forms.

The UE configured with the CORESET knows that it supports PDCCH for a maximum of 4 antenna ports. This information does not tell the UE which antenna port should be used to attempt to blindly decode DCI. The UE may blindly try each of the 4 antenna ports, but this would greatly increase the number of blind decodings. For example, in the case of 4 antenna ports, the blind decoded coefficient is 4.

UE-specific antenna port parameters may be added in the PDCCH-Config message. This is an index into the antenna port table, similar to the method of receiving DCI on PDSCH described above.

The present application provides a working example: both UE1 and UE2 are configured with a CORESET ID of 0. The CORESET supports spatial multiplexing and is configured with an antennaPortTable (fig. 8). In PDDCH-Config, the UE1 is signaled as antennaPorts3, i.e. it should use antenna port 0. The signaling of UE1 is antennaPorts4, i.e., it should use antenna port 1. Both UEs know that the remaining three antenna ports may be used by other UEs. In this manner, the antenna ports of each UE are semi-statically configured.

The advantage of this approach is that if an antenna port (antennaPorts) is 0, then antenna port 0 is used. There is no change in the UE compared to the conventional PDCCH decoding.

If one CORESET supports more than one antenna port, there is one DMRS per antenna port. These DMRSs are (quasi-) orthogonal. These additional DMRSs are defined, e.g., similar to PDSCH. The UE is configured to blindly attempt DMRS for each antenna port to attempt PDCCH decoding. This increases the complexity of PDCCH decoding.

Although the CORESET may be configured with multiple antenna ports, not all DCI within the CORESET must be transmitted through all antenna ports. There may be DCI for a UE that does not support multiple antenna ports of PDCCH, which DCI is transmitted through a single antenna port. That is, these UEs monitor CORESET by attempting demodulation through the single port DMRS as usual. On the other hand, a UE capable of multi-antenna port PDCCH demodulation will monitor CORESET by attempting to demodulate all candidate DMRSs. A signal of the PDCCH demodulation capability of how many antenna ports one UE supports is sent to the gNB before transmission.

Fig. 14 illustrates an example method performed by a base station. At block 301, a base station receives capabilities of one UE. At block 302, the gNB transmits configuration information to configure the UE to receive CORESET, including antenna port configuration information. At block 303, the gNB transmits a first DCI message to the first UE on a downlink control channel, the first DCI message including first DCI for the first UE. The gNB also transmits a second DCI message to the second UE on the downlink control channel, the second DCI message including second DCI for the second UE. The gNB spatially multiplexes the first DCI message and the second DCI message, i.e., they transmit the same or at least partially overlapping time-frequency resources to the first UE and the second UE.

Fig. 15 shows an example method performed by a wireless device UE. At block 311, the UE sends the antenna port capabilities of the UE to the gNB. At block 312, the UE receives configuration information to configure the UE to receive the CORESET, which includes antenna port configuration information. At block 313, the first UE receives a first DCI message on a downlink control channel using the configuration. The first DCI message includes first DCI for the first UE. The first DCI message is spatially multiplexed with a second DCI message transmitted to a second UE.

This application does not specifically show that any device or apparatus forming part of a network may comprise at least a processor, a memory unit, and a communication interface, wherein the processing unit, the memory unit, and the communication interface are configured to perform any of the methods described herein.

Fig. 16 shows an apparatus that may be used to implement a gbb or UE. The device, which may be embodied as any form of computing and/or electronic device. The processing device 500 includes one or more processors 501, which may be microprocessors, controllers, or any other suitable type of processor, for executing instructions to control the operation of the device. The processor 501 is connected to the other components of the device by one or more buses 506. The processor-executable instructions 503 may be provided using any computer-readable medium, such as the memory 502. The processor-executable instructions 503 may include instructions for implementing the functionality of the described methods. The memory 502 is of any suitable type, such as Read Only Memory (ROM), Random Access Memory (RAM), any type of storage device, such as magnetic or optical storage. Data 504 used by the processor may be stored in the memory 502 or in additional memory. The processing device 500 includes one or more wireless transceivers 508.

Further options will be described below. The signal processing functions of embodiments of the present invention may be implemented using computing systems or architectures that are well known to those skilled in the art. For example, a desktop, laptop or computer, handheld computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device may be used as may be desirable or appropriate for a particular application or environment. A computing system may include one or more processors, which may be implemented using a general-purpose or special-purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

The computing system may also include a main memory, such as a Random Access Memory (RAM) or other dynamic memory, for storing information and instructions to be executed by the processor. The main memory may also be used for storing temporary variables or other intermediate information during execution of instructions by the processor. The computing system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system, which may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a Compact Disk (CD) or Digital Video Drive (DVD), a read or write drive (R or RW), or other removable or fixed media drive. The storage medium may include, for example, a hard disk, floppy disk, such a single, compact disk, CD or DVD, or other fixed or removable medium that is read by and written to by the media drive. The storage media may include a computer-readable storage medium having stored therein particular computer software or data.

In other embodiments, information storage systems may include other similar components for allowing computer programs or other instructions or data to be loaded into the computing system. The components may include, for example, a removable storage unit and interface (e.g., a program cartridge and cartridge interface), a removable memory (e.g., a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to the computing system.

The computing system may also include a communications interface. The communication interface may be used to allow software and data to be transferred between the computer system and external devices. Examples of a communication interface may include a modem, a network interface (e.g., an ethernet or other NIC card), a communication port (e.g., a universal serial bus (USB port), a PCMCIA slot and card, etc. software and data transmitted over a communication interface are transmitted in the form of signals, which may be electronic, electromagnetic, and optical signals or other signals capable of being received by the communication interface medium.

In this application, the terms "computer program product," "computer-readable medium," and the like may generally refer to a tangible medium, such as a memory, a storage device, or a storage unit. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. The instructions, generally referred to as "computer program code" (which may be in the form of a computer program or other groupings), when executed, enable the computing system to perform functions of embodiments of the present application. It should be noted that the code may directly cause the processor to perform specified operations, be compiled for execution, and/or be executed in conjunction with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions).

The non-transitory computer readable medium may comprise at least one of the group of: hard disk, optical storage device, magnetic storage device, read-only memory, programmable read-only memory, erasable programmable read-only memory, EPROM, electrically erasable programmable read-only memory, and flash memory. In embodiments where the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into the computing system using, for example, a removable storage drive. When a processor in the computer system executes a control module (in this example, software instructions or executable computer program code), the processor performs the functions described herein.

Furthermore, the concepts of the present application may be applied to any circuit that performs signal processing functions within a network element. It is further contemplated that, for example, a semiconductor manufacturer may employ the concept in the design of a stand-alone device, such as a microcontroller of a Digital Signal Processor (DSP), or an Application Specific Integrated Circuit (ASIC), and/or any other subsystem element.

It will be appreciated that the above description, for clarity, has described embodiments of the application with reference to a single processing logic. However, the inventive concept may equally be implemented by a plurality of different functional units and processors to provide the signal processing functions. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Aspects of the present application may be implemented in any suitable form including hardware, software, firmware or any combination of these. The present application may optionally be implemented at least partly as computer software running on one or more data processors and/or digital signal processors or configurable modular components such as FPGA devices.

Thus, the elements and components of an embodiment of the application may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present application has been described in connection with some embodiments, the present application is not limited to the specific embodiments described. Rather, the scope of the present application is limited only by the accompanying claims. In addition, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although individual features may be included in different claims, these may possibly be combined. The inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Furthermore, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second", etc., do not preclude a plurality.

Although the present application has been described in connection with some embodiments, the present application is not limited to the specific embodiments described. Rather, the scope of the present application is limited only by the accompanying claims. In addition, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Claims (38)

1. A method of wireless transmission between a base station and a group of User Equipments (UEs), the method performed at the base station, comprising:

transmitting a set of Downlink Control Information (DCI) messages on a Downlink Control channel to the set of user equipments, the set of messages including a set of Downlink Control Information indicating at least a first user equipment and a second user equipment in the set of user equipments scheduled to receive data transmissions on a Downlink data channel;

transmitting a first data transmission to the first user equipment on the downlink data channel in accordance with the downlink control information set;

transmitting a second data transmission to the second user equipment on the downlink data channel according to the downlink control information group, wherein the first and second data transmissions are spatially multiplexed.

2. The method of claim 1, wherein the set of downlink control information comprises a bitmap; the bitmap indicates which user equipments in the group of user equipments are scheduled to receive data transmissions on the downlink data channel.

3. The method of claim 2, comprising: transmitting information to one of the group of user devices to indicate an association between the user device and a digit position in the bitmap.

4. The method of claim 3, comprising: transmitting the information to indicate an association when the user equipment is configured to the group of user equipment.

5. The method according to any of the preceding claims, wherein the set of downlink control information comprises a Radio Network Temporary Identifier (RNTI) scheduled to each user equipment receiving data transmission on the downlink data channel.

6. The method of any preceding claim, comprising: transmitting an indication of a Modulation and Coding Scheme (MCS) of the scheduled user equipment.

7. The method of claim 6, wherein transmitting the indication of the modulation and coding scheme comprises transmitting a basic MCS value and transmitting a difference value for at least one other of the scheduled user equipments.

8. The method of claim 6, wherein the indication of the transmission modulation and coding scheme comprises one of:

transmitting a basic MCS value for one of the scheduled user equipments and a difference value for each of the other scheduled user equipments;

transmitting a basic MCS value and a difference value for each of the scheduled user equipments.

9. The method of any preceding claim, comprising transmitting an indication of at least one of the following resource allocations: allocating time resources; frequency resource allocation for each scheduled user equipment.

10. The method of any preceding claim, comprising: transmitting the base value and the difference value for each scheduled user equipment to transmit at least one of the following resource allocations: allocating time resources; frequency resource allocation for each of the scheduled user equipments.

11. The method of any preceding claim, comprising transmitting an indication of antenna ports for at least one scheduled user equipment.

12. A method as claimed in any preceding claim, comprising assigning one user equipment to the group of user equipments.

13. The method of claim 12, comprising sending to the user equipment one or more of: a Radio Network Temporary Identifier (RNTI) specific to the downlink control information group; a group identification of the downlink control information group; resource allocation specific to the downlink control information group.

14. The method according to any of the preceding claims, wherein the message of downlink control information: encoding by a Radio Network Temporary Identifier (RNTI) specific to the set of downlink control information; or by a group identity specific to the downlink control information group; or in a resource allocation specific to the set of downlink control information.

15. The method of any preceding claim, wherein each of the spatially multiplexed transmissions uses the same set of overlapping time-frequency resources.

16. The method according to any of the preceding claims, wherein the downlink control information group indicates a third user equipment in the user equipment group; the third user equipment is scheduled to receive a data transmission on the downlink data channel; the method further comprises sending a data transmission to the third user equipment on the downlink data channel in accordance with the downlink control information group; wherein data transmissions sent to the third user equipment are not spatially multiplexed with data transmissions sent to other invoked user equipment.

17. A method of radio transmission between a base station and a User Equipment (UE), the method performed at the UE comprising:

receiving a message group of Downlink Control Information (DCI) on a Downlink Control channel; the message group comprises a downlink control information group indicating at least a first user equipment and a second user equipment in a group of user equipments scheduled to receive data transmissions on a downlink data channel;

determining from the downlink control information set whether the user equipment is scheduled to receive a data transmission, if the user equipment is scheduled to receive a data transmission, receiving a first data transmission at the user equipment on the downlink data channel according to the downlink control information set; wherein the first data transmission and a second data transmission of another scheduled user equipment are spatially multiplexed.

18. A method of wireless transmission between a base station and a group of User Equipments (UEs), the method performed at the base station, comprising:

transmitting a message group of Downlink Control Information (DCI) to the user equipment group on a Downlink Control channel; the message group comprises a downlink control information group indicating at least a first user equipment and a second user equipment in the user equipment group scheduled to receive data transmissions on a downlink data channel;

transmitting a message of first downlink control information to the first user equipment on the downlink data channel; and

sending a message of second downlink control information to the second user equipment on the downlink data channel; wherein the message of the first downlink control information and the message of the second downlink control information are spatially multiplexed.

19. The method of claim 18, wherein the set of downlink control information comprises a bitmap; the bitmap indicates which user equipments in the group of user equipments are scheduled to receive user equipment specific messages on the downlink data channel.

20. The method of claim 19, comprising transmitting information to one of the group of user devices to indicate an association between the user device and a digit position in the bitmap.

21. The method of claim 20, comprising transmitting the information to indicate association when the user equipment is assigned to the group of user equipment.

22. The method according to any of claims 18 to 21, wherein the downlink control information group comprises an index to a parameter table for receiving a message of the downlink control information specific to a user equipment.

23. The method of claim 22 wherein the parameter table indicates one or more of the following: modulation and Coding Scheme (MCS); allocating time resources; and allocating frequency resources.

24. The method of claim 23, comprising transmitting the parameter table to the ue through Radio Resource Control (RRC) signaling via upper layer signaling.

25. The method according to any of claims 18 to 24, wherein the user equipment specific parameter indicating a frequency resource allocation is a size of the frequency resource allocation; the downlink control information group further includes an indication of a frequency resource allocation for a group scheduling message.

26. The method according to any of claims 18 to 25, wherein the message of user equipment specific downlink control information comprises a plurality of repetitions of user equipment specific downlink control information.

27. The method of claim 26, comprising transmitting an indication of a number of repetitions of the downlink control information specific to a user equipment to at least one of the user equipments.

28. The method according to any of claims 18 to 27, characterized in that a plurality of repetitions of user equipment specific downlink control information are encoded with at least two different redundancy versions.

29. The method of claim 28, wherein an indication of the sequence of redundancy versions is transmitted to the scheduled user equipment.

30. A method of radio transmission between a base station and a User Equipment (UE), the method performed at the UE comprising:

receiving a message group of Downlink Control Information (DCI) on a Downlink Control channel; the message group comprises a downlink control information group indicating at least a first user equipment and a second user equipment in a user equipment group scheduled to receive data transmissions on a downlink data channel;

determining from the downlink control information group whether the user equipment is scheduled to receive a message of downlink control information, if the user equipment is scheduled to receive a message of downlink control information, receiving a message of first downlink control information at the user equipment according to the downlink control information group on the downlink data channel; wherein the message of the first downlink control information and the message of the second downlink control information transmitted to another scheduled user equipment are spatially multiplexed.

31. A method of wireless transmission between a base station, a first User Equipment (UE), and a second UE, the method performed at the base station comprising:

transmitting a first Downlink Control Information (DCI) message to the first user equipment on a Downlink Control channel, the DCI message including first Downlink Control Information of the first user equipment; and

transmitting a message of second downlink control information to the second user equipment on the downlink control channel, the message of second downlink control information including second downlink control information of the second user equipment; wherein the message of the first downlink control information and the message of the second downlink control information are spatially multiplexed.

32. The method of claim 31, wherein the first downlink control information is for scheduling data transmission to a first user equipment; the method comprises the following steps: and transmitting first data to the first user equipment on the downlink data channel according to the first downlink control information.

33. The method according to claim 31 or 32, comprising transmitting a control channel definition comprising an antenna port setting table to allow the first user equipment to receive the first downlink control information.

34. The method of claim 33, comprising transmitting antenna port settings, the settings being an index into the antenna port settings table.

35. The method according to any of claims 31 to 34, comprising receiving antenna port capabilities from said first user equipment and receiving antenna port capabilities from said second user equipment.

36. A method of wireless transmission between a base station and a first User Equipment (UE), the method performed at the first UE, comprising:

receiving setting information to set user equipment to receive control information of a downlink control channel through antenna port setting; and

receiving a first Downlink Control Information (DCI) message on the Downlink Control channel using an antenna port; the message of the first downlink control information comprises first downlink control information of the first user equipment; wherein the message of the first downlink control information and the message of the second downlink control information transmitted to the second user equipment are spatially multiplexed.

37. The method of claim 36, wherein the setting information comprises an antenna port setting table and an antenna port setting, and wherein the antenna port setting is an index of the antenna port setting table.

38. An apparatus for performing the method of any of the preceding claims.

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