WO2011079454A1

WO2011079454A1 - Overlapping resource signaling via code switching

Info

Publication number: WO2011079454A1
Application number: PCT/CN2009/076325
Authority: WO
Inventors: Peng Chen; Tommi Koivisto
Original assignee: Nokia Corporation
Priority date: 2009-12-31
Filing date: 2009-12-31
Publication date: 2011-07-07

Abstract

A user equipment device is provided that includes a processor and a memory. The processor is configured to receive a control signal from a network element, such as an eNB. The control signal includes an indication of whether interference with the apparatus by one or more user equipment devices will occur in one or more scheduled physical resource blocks for transmission. The processor is also configured to determine, based on the indication, whether the interference will occur and to perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

Description

OVERLAPPING RESOURCE SIGNALING VIA CODE SWITCHING

FIELD

[0001] Embodiments generally relate to communications, and in particular to an apparatus, system and method for performing overlapping resource signaling.

BACKGROUND

[0002] In downlink Multiple Input Multiple Output ("MIMO") technology, modifications by the Third Generation Partnership Project ("3GPP") utilizing Dedicated Reference Signals ("DRS") for channel estimation and data modulation for MIMO operation have been adopted in Long Term Evolution ("LTE") release 9. It is anticipated that the same principle will be extended for LTE-Advanced. Multiple User ("MU") MIMO with four or eight transmit antennas at an enhanced Node B ("eNB"), which may be a base station, may assist in achieving spectral efficiency targets (i.e., targets for bandwidth efficiency as a unit of bits/second/Hz). In MU- MIMO, the system attempts to achieve spatial multi-user interference suppression at the transmitter side ("TX"), such as at the eNB.

[0003J U-MIMO makes use of multiple spatial layers, where each spatial layer corresponds to a set of antenna weights at the eNB (i.e., spatial precoding) to reduce interference between the layers and increase power towards the desired user. One spatial layer corresponds to one data stream transmitted using a certain spatial precoding and intended for a target UE device. Generally speaking, for MIMO systems, multiple data streams could be sent to the target UE device at the same time. Spatial precoding for a MU-MIMO system is a set of weights applied to the transmission antennas to achieve higher performance. The difference between layers 1-4 and layers 5-8, where eight layers are used, is in the code length. For layers 1-4, a code length of two is utilized. The code is spread over two adjacent reference signal ("RS") resource elements ("RE"). A resource element is the smallest frequency/time unit in an LTE system. An RE contains one sub-carrier bandwidth in the frequency domain and one symbol in the time domain. For instance, the Walsh Hadamard codes [+1 , +1] and [+1 , -1] may be used to transmit a demodulated reference signal ("DM-RS") for two spatial layers. This results in six instances of the code within a physical resource block ("PRB") and allows four spatial layers to be supported. For layers 5-8, a code length of four is used. In LTE- Advanced, the maximum number of layers supported in LTE-Advanced MU-MIMO is proposed to be four,

SUMMARY

[0004] In an embodiment, a UE device includes a processor and a memory. The processor is configured to receive a control signal from a network element, such as an eNB. The control signal includes an indication of whether interference with the apparatus by one or more user equipment devices will occur in one or more scheduled physical resource blocks for transmission. The processor is also configured to determine, based on the indication, whether the interference will occur and to perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

[0005] In another embodiment, a computer-implemented method includes receiving a control signal from a network element. The control signal includes an indication of whether interference with a use equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission. The method also includes determining, based on the indication, whether the interference will occur and performing blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

[0006] In a further embodiment, an apparatus includes at least one memory including computer-program code and at least one processor. The at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to initiate transmission of a control signal to a user equipment device. The control signal comprises an indication of whether interference with the user equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission. The control signal is configured to permit the user equipment device to determine, based on the indication, whether the interference will occur and perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

[0007] In an additional embodiment, a method includes initiating transmission of a control signal to a user equipment device. The control signal comprises an indication of whether interference with the user equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission. The control signal is configured to permit the user equipment device to determine, based on the indication, whether the interference will occur and perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate. A computer-readable storage medium can be encoded with instructions that, when executed in hardware, perform this method.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order that the embodiments of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. While it should be understood that these drawings illustrate only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0009] Fig. 1 is a block diagram illustrating a computer according to an embodiment of the present invention.

[0010]Fig. 2 is a resource scheduling diagram illustrating scheduling of user equipment over four spatial layers for various PRBs according to an embodiment of the present invention.

[0011] Fig. 3 is a flow diagram illustrating code setting for ports x and y according to an embodiment of the present invention.

[0012] Fig. 4 is a flow diagram illustrating overlapping resource signaling via code switching according to an embodiment of the present invention.

[00 3] Fig. 5 illustrates a method according to certain embodiments of the present invention.

DETAILED DESCRIPTION

[0014]When multiple co-scheduled user equipment ("UE") devices, such as cellular telephones, PDAs and computers, are operating in accordance with MU- MI O, interference between the UE devices sometimes occurs. The interference comes from more than one UE device being scheduled for the same PRB. As such, performing receiver ("RX") side interference suppression may be beneficial for achieving better spectral efficiency. This may be achieved by signaling overlapping resources between UE devices. Overlapping" means that more than one UE device is scheduled for the same PRB. More specifically, in some embodiments, an implicit MU-MIMO indication may be provided on a per-physical resource block ("PRB") basis based at least in part on code division multiplexing ("CDM") code offsetting between slots and related blind detection at UE devices. Blind detection is detection performed by a UE device on a PRB to obtain information regarding overlapping PRBs. The UE device initially does not know which PRBs overlap and which do not.

[0015] It has been observed by the inventors that UE devices in MU mode generally have fairly low mobility and a fairly high signal-to-noise or signal-to- interference-plus-noise ratio ("SINR"). Where UE devices have high mobility, it is generally less desirable for the devices to be in MU mode. This is at least because high mobility may lead to frequent handover between beams, and may lead to MU- MIMO gain being unrealistic. For UE devices with low SINR, it is generally less desirable for the devices to be in MU mode since in such a case, MU interference may make it even harder to provide acceptable quality of service ("QoS") for each UE device.

[0G16] ln order to signal overlapping resources in, for example, LTE-Advanced MU-MIMO, in some embodiments, a bit is utilized to indicate whether one or more interfering UE devices exist for allocated resources (i.e. , on one or more PRBs). It is understood that, to signal "overlapping" information on a per-PRB basis, more control channel overhead would be used. [0017] For 1 -4 layers, in some embodiments, each DRS port (i.e., a set of predefined REs within a PRB that are used to send a DRS) is associated with one length-2 cover code. Certain codes, such as a Walsh Hadamard code, may be used such that the cover codes are orthogonal to each other. Walsh codes are mathematically orthogonal codes that may be used to uniquely define individual communication channels. Thus, if two Walsh codes are correlated, the result is intelligible only if the two codes are the same. Accordingly, a Walsh-encoded signal appears as random noise to a UE device unless that terminai uses the same code as the one used to encode the incoming signal. Per the above, a Walsh code in a 2x2 Hadamard matrix appears as follows:

[0018] For resources without overlap, an eNB applies a corresponding length- 2 cover code to its associated DRS port. For resources with overlap, the eNB applies a corresponding length-2 cover code to its associated DRS port. In addition, a phase rotation is applied to the cover code spanning predefined REs within a same subcarrier. The degree of the phase rotation may be predefined or higher layer configured (e.g. , 180 degree phase rotation). "Higher layer configured" means that the degree of the phase rotation operation is signaled from a higher layer, such as RRC signaling. A network element such as an eNB and UE devices have a common understanding about the cover code phase rotation operation on the overlapping resource.

[0019] Fig. 1 is a block diagram of a computer 100 that can implement an embodiment of the present invention. Computer 100 includes a bus 105 or another communication medium for communicating information, and a processor 1 10 coupled to bus 105 for processing information. Processor 1 10 may be any type of general or specific purpose processor, including a central processing unit {"CPU") or application specific integrated circuit ("ASIC"). Computer 100 further includes a memory 1 15 for storing information and instructions to be executed by processor 1 10. Memory 1 15 can include any combination of random access memory ("RAM"), read only memory ("ROM"), flash memory, cache, static storage such as a magnetic or optical disk, or any other type of computer readable media or combination thereof. Additionally, computer 100 includes a communication device 120, such as a network interface card, a transmitter/receiver, and/or an antenna, to provide access to a network. Therefore, a user may interface with computer 100 directly, or remotely through a network or any other method.

[0020] Computer readable media may be any available media that can be accessed by processor 110 and includes both volatile and nonvolatile media, removable and non-removab!e media, and communication media. Communication media may include computer readable instructions, data structures, program modules or other data received from a modulated data signal such as a carrier wave or other transport mechanism or any other information delivery media.

[0021] Processor 110 is further coupled via bus 105 to a display 125, such as a Liquid Crystal Display ("LCD"), for displaying information to a user, such as server status information. A keyboard/keypad 130 and a cursor control device 135, such as a computer mouse, a touch pad, and/or a button or clickable track wheel, are further coupled to bus 105 to enable a user to interface with computer 100.

[0022] In one embodiment, memory 1 5 stores software modules that provide functionality when executed by processor 110. The modules include an operating system 140 that provides operating system functionality for computer 100. The modules further include overlapping resource signaling module 145 that is configured to facilitate overlapping resource signaling via code switching. Computer 100 can be part of a larger system such as a cluster computing system, a distributed computing system, a cloud computing system, a "server farm" or any other system having multiple servers and/or computing devices. Computer 100 will typically include one or more additional functional modules 150 to include additional functionality. In some embodiments, overlapping resource signaling module 145 may be part of operating system 140 or part of one or more other functional modules included in other functional modules 150.

[0023] It should be noted that many of the functional features described in this specification have been presented as modules in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very large scale integration ("VLSI") circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like.

[0024] Modules may also be at least partially implemented in software for execution by various types of processors. An identified unit of executable code in a software module may, for instance, comprise one or more physical or logical blocks of computer instructions which may, for instance, be organized as an object, procedure or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations that, when joined logically together, comprise the module and achieve the stated purpose for the module. Modules may be stored on a computer- readable medium, which may be, for instance, a hard disk drive, a flash device, random access memory ("RAM"), a tape drive , an optical drive, a compact disk having read-only memory ("CD-ROM") or a digital video disk having read-only memory ("DVD-ROM"), or any other such medium used to store data. The medium may be read-only or read/write. The modules may also be stored on multiple media either residing on the same hardware device or distributed across multiple hardware devices.

[0025] Indeed, a unit of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.

[0026] Fig. 2 is a resource scheduling diagram 200 illustrating scheduling of user equipment over four spatial layers for various PRBs according to an embodiment of the present invention. As can be seen, UE devices #1 through #9 are scheduled for ten PRBs 210-219 over four layers 220, 222, 224 and 226. Each layer has a DRS index of 0 through 3, respectively.

[0027] In MU-MIMO, users are co-scheduled on the same time-frequency resources, and the resulting interference is suppressed using spatial precoding. Spatial precoding involves adjusting antenna weights differently for each user. However, this interference suppression is not perfect since it is based on quantized low-overhead uplink feedback about the radio channel state. Accordingly, interference will occur in some cases. The UE device may cancel the interference if aware of it. To do so, the UE device must know on which PRBs is interference and on which there is not.

[0028JA solution according to embodiments of the present invention is based on blind detection. First, one bit indicates whether there is interference on at least one PRB. When the bit indicates that there is interference, different cover codes are used per PRB depending on whether there is interference or not. The UE device detects the cover code used on each allocated PRB separately. From the detected cover code, the UE device is informed about the interference.

[0029]Since allowing the eNB to have full flexibility in allocating resources among UE devices is generally preferable to increase efficiency of bandwidth usage, the resource allocation among co-scheduled UE devices may not be aligned. In some cases, an "MU-hole" exists in the resources allocated for a certain UE device. Since only one bit is typically used to signal whether a UE device is in MU or single user ("SU") mode, this is not sufficient for signaling which PRBs have overlapping resource allocation with respect to a UE device. For example, take the case where UE #1 and UE #4 interfere. Since UE #1 and UE #4 only overlap for PRBs 210-212, it may be beneficial for UE #1 to know precisely which PRBs may have interference problems. The methods discussed herein may be used to signal such overlapping resources to UE devices so that interference suppression may be performed.

[0030] To further illustrate how some embodiments of the present invention operate, the following example may be useful. Suppose that DRS ports x, y, m and n are available to support LTE-Advanced MU-MIMO operation, and that the maximum number of layers supported by MU-MIMO is four, in this example, port x and port y occupy the same REs. Port m and port n occupy the same REs, but different than those of ports x and y. Port x and port m use the same cover code and port y and port n use the same cover code (but orthogonal to that used by port x and port m).

[0031]After making ML⁾ scheduling decisions, the eNB does the following. In the case that one or more interferers do not exist on the allocated resources (i.e., on any PRBs) the eNB sets a corresponding signaling bit and a cover code for an associated DRS port over all of the allocated resources as shown in Table 1 below.

TABLE 1 - DRS PORT COVER CODES WHEN NO INTERFERERS EXIST

[0032]When interferers exist on allocated resources, eNB sets a corresponding signaling bit and a cover code for associated DRS ports over the corresponding resources as shown in Table 2.

TABLE 2 - DRS PORT COVER CODES WHEN INTERFERERS EXIST

[0033] Fig. 3 is a flow diagram 300 illustrating code setting for ports x, y, m and n according to an embodiment of the present invention. Frequency is illustrated along the y-axis and time is illustrated along the x-axis. The square sets of four dark blocks represent REs used by the ports. The pairs of REs 310 and 320 are used by ports x and y, and the pairs of REs 330 and 340 are used by ports m and n. This pattern is repeated two more times in the figure. Ports x and y are separated by cover codes, and ports m and n are separated by cover codes. [0034] For resources without overlapping, a DRS scrambling sequence where UE identifier (RNTI) is included for sequence initialization, is applied. For resources overlapping with interferes, a DRS scrambling sequence, where signaled ID (e.g. via Physical Downlink Control Channel ("PDCCH")) is included for signal initialization, is applied. On the UE side, when a UE device determines based on this information that one or more interferers exist for the allocated resources, blind detection is performed on the associated resources to find the phase offset between two length-2 cover codes, and the resource overlapping information is retrieved accordingly. This approach will not impact channel estimation granularity; there are still six instances of the code per PRB, as illustrated in Fig. 3.

[0035]The performance of blind detection may be degraded in a fast-time- variant channel environment or noise-limited environment. However, per the above, a user in such an environment is unlikely to be in MU mode. Blind detection only needs to be performed in MU mode since the above-discussed method provides an indication of whether PRBs are interfered with or not. Hence, SU performance is not impacted by potential blind detection failures, and as mentioned, MU mode is likely to happen when there is a high SINR so blind detection errors should be infrequent.

[0036]When the MU bit indicator is set, the blind detection would be performed at the UE device, for example, by dispreading the signal received at pilot locations with the code with two possible phase offsets (i.e., 0 degrees and 80 degrees), and checking which phase offset candidate offers a larger correlation peak (hence a simple comparison). There are multiple instances of the codes within the PRB - three instances in the example shown in Fig. 3. Accordingly, the UE device may combine the correlation results in numerous ways, such as noncoherent combining, coherent combining and selection combining. In noncoherent combining, squared absolute values of the dispreading outputs within the PRB are summed. This may be a practical solution when a channel is expected to be changed between different instances of the code (e.g. , frequency selective channel). In coherent combining, the pure dispreading output values are summed without squaring or taking absolute values. This is typically only feasible in non-selective channels where the channel can be assumed to be fairly flat over the PRB. In selection combining (a.k.a., majority voting), the candidate with the most frequent occurrence of the largest correlation peak is selected. The received signal is correlated with possible cover codes and the correlation results are compared. The largest correlation result is said to be a "correlation peak". For instance, if candidate 1 produces the largest correlation peak in two cases and candidate 2 produces the largest correlation peak in one case, candidate 1 is selected. This method tends to be suboptimal.

[0037] Fig. 4 is a flow diagram 400 illustrating overlapping resource signaling via code switching according to an embodiment of the present invention. In some embodiments, the overlapping resource signaiing may be performed by computer 100 of Fig. 1 via overlapping resource signaling module. The process starts with a UE device receiving a control signal from an eNB at 410. The control signal includes an indication of whether interference with the UE device by one or more other UE devices will occur in one or more scheduled PRBs for transmission. In some embodiments, the cover code may have a length of 2 and multiple spatial layers (such as four) may be supported for MU-MIMO operation. Based on this information, the UE device then determines whether interference will occur for one or more PRBs at 420.

[0038] If it is not determined that there is interference at 430, the process ends. Otherwise, the UE device retrieves multiple instances of the cover code from a physical resource block at 440. The UE device then combines correlation results at 450 and determines a phase offset candidate that offers a larger correlation peak at 460. For instance, if having a larger correlation peak, a phase offset of 0 degrees as opposed to 180 degrees may be selected. The correlation peaks for the phase offset candidates may be determined using such methods as noncoherent combining, coherent combining and selection combining. Finally, the UE device applies a phase offset based on the determined phase offset candidate at 470.

[0039] Fig, 5 illustrates a method 500 according to certain embodiments of the present invention. As illustrated, the method includes initiating transmission 520 of a control signal to a user equipment device. Before initiating transmission the signal can be generated. Generating the signal can involve including 510 in the control signal an indication of whether interference with the user equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission. The control signal can be configured to permit the user equipment device to determine, based on the indication, whether the interference will occur and perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate. In a specific instance, the control signal can be a one bit indication.

[0040]Additionally, the method of Fig. 5 can include setting a cover code 530 for at least one associated dedicated reference signal port over all allocated resources. This setting of the cover code 530 may involve performing cover code offsetting operation for the overlapped PRBs. Thus, the eNB sends a control signal to indicate that interference exists and applies the cover code and phase rotation for overlapped resources.

[0041] While the term "computer" has been used in the description of some embodiments of the present invention, the invention may be applied to many types of network computing devices. For purposes of this invention, the term "computer" includes rack computing systems, cloud computing systems, distributed computing systems, personal computers, laptops, cell phones, persona! digital assistants, tablet computing devices, mainframes, any networked devices that perform computing operations, and any equivalents thereof.

[0042] One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced in a different order, and/or with hardware elements in configurations that are different than those that are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to, and readily appreciated by, those of ordinary skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.

[0043] It should be noted that reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.

[0044] Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

Claims

WHAT IS CLAIMED IS:

1. An apparatus, comprising:

a processor; and

a memory, wherein the processor is configured to

receive a control signal from a network element, wherein the control signal comprises an indication of whether interference with the apparatus by one or more user equipment devices will occur in one or more scheduled physical resource blocks for transmission,

determine, based on the indication, whether the interference will occur, and

perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

2. The apparatus of claim 1, wherein the apparatus is further configured to:

retrieve multiple instances of the cover code from a physical resource block; and

combine correlation results to determine the phase offset candidate that offers a larger correlation peak.

3. The apparatus of claim 2, wherein the processor is configured to determine the phase offset candidate using noncoherent combining, coherent combining or selection combining.

4. A computer-implemented method, comprising:

receiving a control signal from a network element, wherein the control signal comprises an indication of whether interference with a use equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission;

determining, based on the indication, whether the interference will occur; and performing blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

5. The method of claim 4, further comprising:

retrieving multiple instances of the cover code from a physical resource block; and

combining correlation results to determine the phase offset candidate that offers a larger correlation peak.

6. The method of claim 5, further comprising:

determining the phase offset candidate using noncoherent combining, coherent combining or selection combining.

7. A computer program embodied on a computer-readable medium, the program configured to control a processor to:

receive a control signal from a network element, wherein the control signal comprises an indication of whether interference with a user equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission,

determine, based on the indication, whether the interference will occur, and perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

8. An apparatus, comprising:

at least one memory including computer-program code; and

at least one processor,

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to

initiate transmission of a control signal to a user equipment device, wherein the control signal comprises an indication of whether interference with the user equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission,

wherein the control signal is configured to permit the user equipment device to determine, based on the indication, whether the interference will occur and perform blind detection of overlapped resources based at least in part on a cover code for a dedicated reference signal port to determine a phase offset candidate.

9. The apparatus of claim 8, wherein the control signal comprises a one bit indication.

10. The apparatus of claim 8 or 9, wherein the at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to set a cover code for at least one associated dedicated reference signal port over all allocated resources.

11 . The apparatus of any of claims 8-10, wherein the cover code has a length of two and multiple spatial layers are supported for multiple user, multiple input multiple output ("MU- IMO") operation.

12. The apparatus of any of claims 8-11 , wherein four ports, x, y, m and n, are available, ports x any y occupy the same resource elements, ports m and n occupy the same resource elements that differ from those occupied by ports x and y, ports x and m use the same cover code and ports y and n use the same cover code, but the cover code used by ports y and n is orthogonal to the cover code used by ports x and m.

13. The apparatus of any of claims 8-12, wherein two possible phase offset candidates exist, one with a 0 degree phase offset and the other with a 180 degree phase offset.

14. A method, comprising:

initiating transmission of a control signal to a user equipment device, wherein the control signal comprises an indication of whether interference with the user equipment device by one or more other user equipment devices will occur in one or more scheduled physical resource blocks for transmission,

15. The method of claim 14, wherein the control signal comprises a one bit indication.

16. The method of claim 14 or 15, further comprising:

setting a cover code for at least one associated dedicated reference signal port over all allocated resources.

17. The apparatus of any of claims 14-16, wherein the cover code has a length of two and multiple spatial layers are supported for multiple user, multiple input multiple output ("MU-MIMO") operation.

18. The apparatus of any of claims 14-17, wherein four ports, x, y, m and n, are available, ports x any y occupy the same resource elements, ports m and n occupy the same resource elements that differ from those occupied by ports x and y, ports x and m use the same cover code and ports y and n use the same cover code, but the cover code used by ports y and n is orthogonal to the cover code used by ports x and m.

19. The apparatus of any of claims 14-18, wherein two possible phase offset candidates exist, one with a 0 degree phase offset and the other with a 180 degree phase offset

20. A computer-readable storage medium encoded with instructions that, when executed in hardware, perform a process, the process comprising: