Joint Transmission in a Wireless Network

Abstract

A system for receiving joint transmission wireless signals may include a transceiver to receive a plurality of colliding wireless signals. One of the wireless signals may include reference signal data while another of the wireless signals may include user data. The reference signal data may be combined with the user data into a superimposed signal. The reference signal data may be filtered out from the superimposed data, and the user data may be decoded.

Description

BACKGROUND

This relates generally to sending data over wireless networks.

As mobile and wireless networks grow in popularity, radio and wireless communication standards must adapt to meet ever increasing bandwidth requirements and user demand. Such standards include the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) and Long Term Evolution-Advanced (LTE-Advanced) systems.

Using these protocols, various devices may use wireless communication schemes to communicate with a data network. For example, each device may establish a wireless connection to a local base station in order to access a broader data network. Thus, multiple devices may communicate with each other by accessing the data network through multiple base stations.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are described with respect to the following figures:

FIG. 1 is a schematic depiction of an example network configuration in accordance with one or more embodiments;

FIG. 2 is a depiction of a table used by an example network configuration in accordance with one or more embodiments;

FIG. 3 is a schematic depiction of an example user device in accordance with one or more embodiments;

FIG. 4 is a schematic depiction of an example base station in accordance with one or more embodiments; and

FIG. 5 is a flow chart in accordance with one or more embodiments.

DETAILED DESCRIPTION

In wireless communications, one area of particular interest may be cooperative multiple point (CoMP) transmission. Under CoMP multiple base stations may be able to transmit downlink signals to a user device at the same time. The user device may then try to decode all the downlink signals simultaneously in order to improve reception conditions and increase data throughput.

Under 3GPP LTE and LTE-Advanced, one type of CoMP transmission under Scenario 3 may be joint processing. During joint processing, multiple base stations may coordinate with each other to simultaneously transmit to and from user devices. As such, there may be an increased chance of signal collision between the various signals sent by the base stations. For example, reference signals used to estimate channel conditions may collide and/or interfere with signals containing user data. User devices may thus encounter some challenges in decoding and differentiating the various signals.

Some strategies for reducing interference between user data and reference signals may include muting certain portions of the user data signal during transmission. While doing so may reduce interference, muting portions of the user data signal may decrease data throughput to the user device and may cause the user device to underestimate the level of interference during channel estimation.

FIG. 1 represents a system 100 for filtering reference signal data from user data in a wireless network according to one or more embodiments. The system may include a user device 110 in communication with multiple base stations 130a-c. In some implementations, the user device 110 may include a joint processing module 120 capable of receiving multiple signals simultaneously from the base stations 130a-b. For example, each base stations 130a-b may send a reference signal 140a-c and user data 150a-c to the user device 110.

The user device 110 may be any electronic device capable of communication over a wireless network. For example, the user device 110 may include a desktop computer, laptop computer, mobile phone, tablet personal computer, personal digital assistant, digital camera, and/or any other electronic device. Furthermore, while FIG. 1 illustrates only one user device 110, it should be understood that any number of user devices may be in communication with the base stations 130a-c.

In some implementations, the system 100 may operate according to LTE-Advanced specifications. As such, the base stations 130a-c may be referred to as evolved Node Bs (eNBs) while the user device 110 may be referred to as user equipment (UE). Furthermore, the system 100 may be capable of using cooperative multiple point transmission (CoMP) Scenario 3. In particular, the base stations 130a-c may have the ability to perform joint processing to coordinate transmission of various signals simultaneously to the user device 110.

Thus, in one or more embodiments, some of these signals may include reference signals 140a-c and user data 150a-c. For example, the reference signals 140a-c may be cell specific reference signals (CRS) sent to the user device 110 to perform channel estimation. The user device 110 may compare characteristics of the reference signals 140a-c as they are received to their characteristics when they were sent. By analyzing any differences in these characteristics, channel estimation may be calculated.

User data 150a-c may be any data including image data, video data, media data, control data and/or the like. Furthermore, the user data 150a-c may be sent on the physical downlink shared channel (PDSCH) according to the LTE-Advanced specification. In some implementations using joint processing of the base stations 130a-c, the reference signals 140a-c and the user data 150a-c may experience interference with each other. Thus, the joint processing module 120 may receive the interfering signals and filter out one or more of the reference signals 140a-c and/or user data 150a-c.

Thus, the joint processing module 120 may receive the interfering signals and filter out one or more of the reference signals 140a-c and/or user data 150a-c. In some embodiments, the join processing module 120 may be capable of performing successive interference cancellation (SIC). SIC may enable the join processing module 120 to decode two or more signals concurrently. For example, suppose a first signal and a second signal reach the join processing module 120 simultaneously to form a combined signal and that the first signal is the stronger of the two. Using SIC, the join processing module 120 may first decode the first signal, which is stronger, and then subtract the first signal out from the combined signal. As a result, the join processing module 120 may then be able to extract the second, weaker signal from the residue.

In some embodiments, the joint processing module 120 may simultaneously receive a reference signal 140a-c and user data 150a that interfere and/or collide with one another. Under the LTE and LTE-Advanced, such collisions may occur on one or more collided resource elements. A resource element may be the basic unit of physical resource in LTE and may be represented as an indexed pair of a sub-carrier and a modulation (e.g., Orthogonal frequency-division multiplexing (OFDM)) symbol.

Thus, a collided resource element may include a superimposed signal of both the reference signal 140a-c and the user data 150a-c. Because the reference signal 140a-c may be the stronger signal, the joint processing module may first detect the reference signal 140a-c and estimate its channel response. Then, the joint processing module 120 may perform SIC on the superimposed signal to filter out the reference signal 140a-c. That is, the reference signal 140a-c may be reconstructed and subtracted out from the superimposed signal. As a result of the subtraction, the remaining downlink user data 150a-c may be detected and/or decoded.

In some embodiments, a precoded data symbol may be sent over a pair of collided resource elements. Thus, the collided resource elements may be used as a pair during decoding of the data symbol. For example, after canceling the reference signal 140a-c on the pair of collided resource elements, each resource element of the pair may include parts of the precoded data symbol. However, due to the cancelation, some noise may still be present that obscures coherent decoding of the data symbol. Therefore, the remaining signal on each collided resource element may be combined, and decoding of the data symbol may be performed on this combined signal.

In some embodiments, simultaneous transmission of reference signals 140a-c and user data 150a-c from multiple base stations 130a-c over collided resource elements may be viewed as a form of spatial multiplexing between the base stations 130a-b. Furthermore, from the perspective of a single resource element, the spatial multiplexing can be viewed as a mathematical expression. For example, the mathematical expression for using two collided resource elements (from two different joint transmission cells e.g., base stations 130a-b) to transmit one user data 150a-c resource element (e.g., a PDSCH resource element) is given below. These mathematical expressions may be in the context of the LTE and/or LTE-Advanced specifications.

The following expressions may be made with focus on resource element 16 of FIG. 2. First, the transmission of one PDSCH resource element over two collided resource elements can be expressed as equation (1)

$\begin{array}{cc}\{\begin{array}{c}{\stackrel{\_}{y}}_3^{16}=H_1^{16}P_1\stackrel{\_}{s}+H_2^{16}{\stackrel{\_}{e}}_2r_2+{\stackrel{\_}{n}}_1\\ {\stackrel{\_}{y}}_2^{16}=H_2^{16}P_2\stackrel{\_}{s}+H_1^{16}{\stackrel{\_}{e}}_1r_1+{\stackrel{\_}{n}}_2\end{array}& \left(1\right)\end{array}$

where y_i¹⁶ is the received vector when PDSCH of cell i sends reference signalr_i and the remaining joint transmission cell send data (vector or symbol) s; r_i is the reference signal sent by cell i; H_i¹⁶ is the channel matrix of the downlink channel from cell i eNB (base station 130a-c) to the UE (user device 110); P_i is the beamforming matrix for sending the data s from cell i eNB to the UE; ē_i is the antenna selection vector e.g. [1 0 . . . 0]^T for cell i eNB; n_i is the noise vector seen by the UE when cell i sends reference signalr_i. It should be noted that the full beamforming matrix of the joint transmission on the non-collided resource element is

$P=\left[\begin{array}{c}{P}_1\\ P_2\end{array}\right].$

Namely, the full beamforming matrixes of the joint transmission on the collided resource element are

$\left[\begin{array}{c}{P}_1\\ 0\end{array}\right]$ $\mathrm{and}\left[\begin{array}{c}0\\ P_2\end{array}\right]$ $\mathrm{with}$ $P=\left(\left[\begin{array}{c}{P}_1\\ 0\end{array}\right]+\left[\begin{array}{c}0\\ P_2\end{array}\right]\right)$

corresponding to the upper and lower parts of P, respectively. In other words, the UE may observe different parts of the full beamformed channel on each collided resource element.

After cancelling the reference signal interference, the UE may combine the two partial observations to get the full observation of data s as:

$\begin{array}{cc}{\stackrel{\_}{y}}^{16}=\left({\stackrel{\_}{y}}_1^{16}+{\stackrel{\_}{y}}_2^{16}\right)=[\begin{array}{cc}{H}_1^{16}& H_2^{16}]\left[\begin{array}{c}{P}_1\\ P_2\end{array}\right]\stackrel{\_}{s}+\stackrel{\_}{n}\end{array}& \left(2\right)\end{array}$

It should be noted that H^k=[H₁^k H₂^k] is the full channel matrix for joint transmission on the k-th resource element and

$P=\left[\begin{array}{c}{P}_1\\ P_2\end{array}\right]$

is the beamforming matrix for the non-collided resource element. Finally, the UE may use the reference signal to coherently decode the PDSCH using the observations from both collided and non-collided resource elements. Other resource elements such as resource elements 13, 14 and 15 in FIG. 2 can be processed in a similar manner.

In some embodiments under the LTE and/or LTE-Advanced specifications, it may be desirable for the user device to operate at a relatively high Signal to Interference and Noise Ration (SINR). Thus, a relatively high modulation and coding scheme (MCS) may typically be selected for PDSCH transmission (i.e., transmission of user data 150a-c) from a base station 130a-c to a user device 110. However, the higher the MCS that is selected for PDSCH transmission from a particular base station, the more susceptible the PDSCH transmission may be to interference with reference signals from other base stations. Furthermore, even after performing interference cancelation as described above, interference with residual reference signals may still occur. In other words, PDSCH transmission using relatively high MCS may still be susceptible to interference from residual reference signals under a joint transmission scheme.

Thus, in one or more embodiments, a lower MCS order may be used for PDSCH transmission, relative to the initial MCS order fed back by a user device, on resource elements that collide with reference signals 140a-c (e.g., resource elements 14, 16, 18, and 20 in FIG. 2). For the other resource elements that do not experience any collision during PDSCH transmission, the initial MCS order fed back by the user device 110 may still be used. For example, suppose a user device 110 feeds back a MCS order corresponding to 64QAM. In this scenario, the PDSCH transmitting base station 130a-c may elect to use 16QAM/QPSK in resource elements that have collisions with reference signal data 140a-c and maintain 64QAM in the other resource elements. Thus, a relatively high throughput for PDSCH transmission may be maintained with relatively low interference from reference signal data during joint transmission.

In other embodiments, a relatively high MCS order may be used during any PDSCH transmission. However, the user device 110 may elect to demodulate the relatively high order MCS as a lower order MCS. For example, the user device 110 may set the log likelihood ration (LLR) of some bits to zero.

FIG. 3 represents a system depiction of the user device 130 of FIG. 1. The user device may include a receiver 310 for receiving data and a transmitter 320 for transmitting data. In one or more embodiments, the receiver 310 and the transmitter 320 may be combined to form a transceiver capable of both receiving and transmitting data. For example, the receiver 310 may receive the reference signal 120a-b from the base station 105 while the transmitter 320 may transmit the CSI signal 125 back to the base station 105.

Additionally, the user device 110 may also include a memory 330 for storing instructions and a processor 340 for executing those instructions. In one or more embodiments, Join Processing Module 120 (not shown) may include the processor 340 and memory 330 or may be otherwise in communication with the processor 340 and the memory 330. In other embodiments, the Join Processing Module 120 may be a program stored in the memory 330, and thereby provide instructions for the processor 340 to execute. As such, the processor 340 may carry out instructions from the Join Processing Module 120 to perform interference canceling as described above with reference to FIG. 1.

While FIG. 3 illustrates only one of each component, it should be understood that multiple instances of these components are also contemplated within the present disclosure. For example, the user device 110 may also include more than one processor and more than one memory. Furthermore, the user device 110 may also include multiple storage devices.

Similarly, FIG. 4 represents a system depiction of an example base station 130a-c that may be used to perform joint transmission with other base stations 130a-c to the user device 110. Thus, the base station 130a-c may include similar components to those illustrated in the user device 110 of FIG. 3. Specifically, the base station 130a-c may also include a receiver 410, and transmitter 420, a processor 440, and memory 430. Additionally, the base station 105 may also include a router 450 to route communication between various user devices. In one or more embodiments, the memory 430 may store the table 200 illustrated in FIG. 2.

Furthermore, the base station 130a-c may also include a Joint Transmission Logic (not shown) in communication with the processor 440 and memory 460. In one or more embodiments, Joint Transmission Logic 108 may include the processor 440 and memory 430. In other embodiments, the Joint Transmission Logic 130 may be a program stored in the memory 430, and thereby provide instructions for the processor 440 to execute. As such, the processor 440 may carry out instructions from the Joint Transmission Logic 108 to determine joint transmission signaling as described above with reference to FIG. 1. For example, the joint transmission logic 108 may determine that for a particular PDSCH transmission, a different MCS is to be used than the initial MCS fed back from the user device 120.

FIG. 5 represents a flow diagram depicting a method 500 for performing joint transmission in a wireless network according to one or more embodiments. The method may begin in step 510 when a user device wirelessly receives a plurality of colliding wireless signals, from a base station. One of the colliding wireless signals may include reference signal data while the other wireless signal may include user data.

Then, in step 520, the reference signal data and the user data may be combined into a superimposed signal. In step 530, the user device may filter out the reference signal data from the superimposed signal. As previously discussed, this process may involve Successive Interference Canceling by the user device.

Finally, in step 540, the user device may decode the user data from the superimposed signal. Thus, the user device may be capable of receiving simultaneous joint transmissions from multiple base stations even through significant amount of signal collision and interference. Furthermore, such joint transmission may be received without having to mute certain colliding user data resource elements that would otherwise decrease user data throughput to user device.

Instructions of software described above (including the steps described in FIG. 5) may be loaded for execution on a processor (such as the processor illustrated in FIG. 3 and/or FIG. 4) A processor can include a microprocessor, microcontroller, processor module or subsystem, programmable integrated circuit, programmable gate array, or another control or computing device. As used here, a “processor” can refer to a single component or to plural components (e.g., one CPU or multiple CPUs).

Data and instructions are stored in respective storage devices, which are implemented as one or more computer-readable or machine-readable storage media. The storage media include different forms of memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy and removable disks; other magnetic media including tape; optical media such as compact disks (CDs) or digital video disks (DVDs); or other types of storage devices. Note that the instructions discussed above can be provided on one computer-readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine-readable storage medium or media is (are) considered to be part of an article (or article of manufacture). An article or article of manufacture can refer to any manufactured single component or multiple components. The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site from which machine-readable instructions can be downloaded over a network for execution.

In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some or all of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.

References throughout this specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation encompassed within the present invention. Thus, appearances of the phrase “one embodiment” or “in an embodiment” are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be instituted in other suitable forms other than the particular embodiment illustrated and all such forms may be encompassed within the claims of the present application.

The following clauses and/or examples pertain to further embodiments:

One embodiment may include a method including: receiving, at a user equipment (UE) operating within a 3^rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network via a Cooperative Multiple Point Transmission (CoMP) Scenario 3, a plurality of colliding wireless signals, wherein one of the wireless signals comprises reference signal data and another of the wireless signals comprises user data sent over a Physical Downlink Shared Channel (PDSCH); combining the reference signal data with the first user data into a superimposed signal; filtering out the reference signal data from the superimposed signal; and decoding the user data from the superimposed signal.

The method may also include that the colliding wireless signals are received from evolved node Bs (eNBs) simultaneously transmitting to the UE. The method may also include that the colliding wireless signals are sent as a joint transmission from the eNBs.

Furthermore, the method may also include that filtering out the reference signal data from the superimposed signal includes: detecting the reference signal data from the superimposed signal; estimating at least one channel response from the reference signal data; and subtracting the reference signal data from the superimposed wireless signal. The method may also include that after subtracting the reference signal data from the superimposed signal, the remaining part of the superimposed signal is the user data. The method may also include that the plurality of colliding wireless signals are sent over colliding resource elements.

Additionally, the method may include that the reference signal data is received on a first resource element, and the user data is received on a second resource element. The method may also include that the colliding reference signals are cell-specific reference signals. The method may also include that none of the user data is muted.

Another embodiment may also be at least one machine readable medium including a plurality of instructions that in response to being executed by a computer device, cause the computer device to carry out the above-described method.

A further embodiment may be a user equipment (UE)including: a transceiver; and a joint processing module having a memory and a processor, wherein the UE operates within a 3^rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network, and wherein the memory is to store instructions, and the processor is to execute the instructions to: receive, at the transceiver via a Cooperative Multiple Point Transmission (CoMP) Scenario 3, a first wireless signal on a first resource element colliding with a second wireless signal on a second resource element, wherein the first wireless signal comprises reference signal data and the second wireless signal comprises user data sent over a Physical Downlink Shared Channel (PDSCH); combine the reference signal data with the user data into a superimposed signal; filter out the reference signal data from the superimposed signal; and decode the user data from the superimposed signal.

The UE may also include a display. The UE may also include that the colliding wireless signals are received from multiple base stations simultaneously transmitting to the system. The UE may also include that the instructions to filter out the reference signal data from the superimposed signal further include instructions to: detect the reference signal data from the superimposed signal; estimate at least one channel response from the reference signal data; and subtract the reference signal data from the superimposed wireless signal.

Furthermore, the UE may include that after subtracting the reference signal data from the superimposed signal, the remaining part of the superimposed signal is the user data. The UE may also include that the plurality of colliding wireless signals are cell-specific reference signals.

Another embodiment may be an evolved node B (eNB), including: a transceiver; and a joint transmission logic having a memory and a processor, wherein the eNB operates within a 3^rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network, wherein the memory is to store instructions, and the processor is to execute the instructions to: receive, via the transceiver, an initial modulation and coding scheme from a user equipment (UE); and transmit user data, using a lower modulation and coding scheme than the initial modulation and coding scheme, over a first resource element that collides with reference signal data over a second resource element.

The eNB may also include that the memory further comprises instructions to transmit, using the initial modulation and coding scheme, user data over a third resource element that does not collide with reference signal data. The eNB may also include that the reference signal data originates from a second eNB transmitting to the UE simultaneously with the eNB via the Cooperative Multiple Point Transmission (CoMP) Scenario 3.

Claims

1. A method, comprising: receiving, at a user equipment (UE) operating within a 3rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network via a Cooperative Multiple Point Transmission (CoMP) Scenario 3, a plurality of colliding wireless signals, wherein one of the wireless signals comprises reference signal data and another of the wireless signals comprises user data sent over a Physical Downlink Shared Channel (PDSCH);combining the reference signal data with the user data into a superimposed signal;filtering out the reference signal data from the superimposed signal; anddecoding the user data from the superimposed signal.

2. The method of claim 1, wherein the colliding wireless signals are received from multiple evolved node Bs (eNBs) simultaneously transmitting to the UE.

3. The method of claim 2, wherein the colliding wireless signals are sent as a joint transmission from the multiple eNBs.

4. The method of claim 1, wherein filtering out the reference signal data from the superimposed signal comprises: detecting the reference signal data from the superimposed signal;estimating at least one channel response from the reference signal data; andsubtracting the reference signal data from the superimposed wireless signal.

5. The method of claim 4, wherein after subtracting the reference signal data from the superimposed signal, the remaining part of the superimposed signal is the user data.

6. The method of claim 1, wherein the plurality of colliding wireless signals are sent over colliding resource elements.

7. The method of claim 6, wherein the reference signal data is received on a first resource element, and the user data is received on a second resource element.

8. The method of claim 6, wherein the colliding reference signals are cell-specific reference signals.

9. The method of claim 1, wherein none of the user data is muted.

10. At least one non-transitory machine readable medium comprising a plurality of instructions that in response to being executed by a computer device, cause the computer device to carry out a method comprising: receiving, at a user equipment (UE) operating within a 3rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network via a Cooperative Multiple Point Transmission (CoMP) Scenario 3, a plurality of colliding wireless signals, wherein one of the wireless signals comprises reference signal data and another of the wireless signals comprises user data sent over a Physical Downlink Shared Channel (PDSCH);combining the reference signal data with the user data into a superimposed signal;filtering out the reference signal data from the superimposed signal; anddecoding the user data from the superimposed signal.

11. A user equipment (UE), comprising: a transceiver; anda joint processing module having a memory and a processor, wherein the UE operates within a 3rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network, and wherein the memory is to store instructions, and the processor is to execute the instructions to:receive, at the transceiver via a Cooperative Multiple Point Transmission (CoMP) Scenario 3, a first wireless signal on a first resource element colliding with a second wireless signal on a second resource element, wherein the first wireless signal comprises reference signal data and the second wireless signal comprises user data sent over a Physical Downlink Shared Channel (PDSCH);combine the reference signal data with the user data into a superimposed signal;filter out the reference signal data from the superimposed signal; anddecode the user data from the superimposed signal.

12. The UE of claim 11, wherein a precoded data symbol is to be sent over the first resource element and the second resource element.

13. The UE of claim 12, wherein filtering out the reference signal data results in a first remaining signal on the first resource element and a second remaining signal on a second resource element.

14. The UE of claim 13, wherein the instructions to decode the user data from the superimposed signal further comprise instructions to: combine the first remaining signal with the second remaining signal.

15. The UE of claim 11, wherein the instructions to filter out the reference signal data from the superimposed signal further comprise instructions to: detect the reference signal data from the superimposed signal;estimate at least one channel response from the reference signal data; and subtract the reference signal data from the superimposed wireless signal.

16. The UE of claim 14, wherein after subtracting the reference signal data from the superimposed signal, the remaining part of the superimposed signal is the user data.

17. The UE of claim 11, wherein the plurality of colliding wireless signals are cell-specific reference signals.

18. An evolved node B (eNB), comprising: a transceiver; anda joint transmission logic having a memory and a processor, wherein the eNB operates within a 3rd Generation Partnership Project (3GPP), Long Term Evolution-Advanced (LTE-Advanced) network, wherein the memory is to store instructions, and the processor is to execute the instructions to:receive, via the transceiver, an initial modulation and coding scheme from a user equipment (UE); andtransmit user data over a Physical Downlink Shared Channel (PDSCH), using a lower modulation and coding scheme than the initial modulation and coding scheme, over a first resource element that collides with reference signal data over a second resource element, wherein the user data is transmitted via a Cooperative Multiple Point Transmission (CoMP) Scenario 3.

19. The eNB of claim 18, wherein the memory further comprises instructions to: transmit, using the initial modulation and coding scheme, user data over a third resource element that does not collide with reference signal data.

20. The eNB of claim 18, wherein the reference signal data originates from a second eNB transmitting to the UE simultaneously with the eNB via the Cooperative Multiple Point Transmission (CoMP) Scenario 3.

21. The medium of claim 10, wherein the colliding wireless signals are received from multiple evolved node Bs (eNBs) simultaneously transmitting to the UE.

22. The medium of claim 11, wherein the colliding wireless signals are sent as a joint transmission from the multiple eNBs.

23. The medium of claim 10, wherein filtering out the reference signal data from the superimposed signal comprises: detecting the reference signal data from the superimposed signal;estimating at least one channel response from the reference signal data; andsubtracting the reference signal data from the superimposed wireless signal.

24. The medium of claim 13, wherein after subtracting the reference signal data from the superimposed signal, the remaining part of the superimposed signal is the user data.

25. The medium of claim 10, wherein the plurality of colliding wireless signals are sent over colliding resource elements.

26. The medium of claim 15, wherein the reference signal data is received on a first resource element, and the user data is received on a second resource element.

27. The medium of claim 15, wherein the colliding reference signals are cell-specific reference signals.

28. The medium of claim 10, wherein none of the user data is muted.