EP3050235A1 - Methods and nodes in a wireless communication system enabling equal error protection with adaptive hierarchical modulation - Google Patents

Abstract

Method (700) in a transmitter (110), a transmitter (110), a method (900) in a recipient (120) and a recipient (120) for multiplexing data streams (130-1, 130-2) by providing dynamic stream-to-label mapping. The method (700) comprises: transmitting (701 ) data on a plurality of data streams (130-1, 130-2); obtaining (702) a channel quality estimation; selecting (703) data streams (130-1, 130-2), based on the obtained (702) channel quality estimation; determining (704) a modulation scheme (400); forming (705) a binary label (420) and mapping bit positions in such label (420) with a selected (703) data stream (130-1, 130-2); determining (706) the binary label (420) by collecting bits (b1, b2, bn) from the data streams (130-1, 130-2); selecting (707) a constellation point (410) in the determined (704) modulation scheme (400), according to the binary label (420); and transmitting (708) data representing the selected (707) constellation point (410) in a time-frequency resource element.

Description

METHODS AND NODES IN A WIRELESS COMMUNICATION SYSTEM ENABLING EQUAL ERROR PROTECTION WITH ADAPTIVE HIERARCHICAL MODULATION

TECHNICAL FIELD

Implementations described herein generally relate to a method in a transmitter, a transmit- ter, a method in a recipient and a recipient. In particular is herein described a mechanism for the concurrent transmission of multiple independent data streams by providing dynamic stream-to-label mapping; thereby efficiently sharing the same physical resources, yet providing a similar error protection level of the transmitted data streams. BACKGROUND

A User Equipment (UE), also known as a recipient, a mobile station, wireless terminal and/ or mobile terminal is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system or a wireless communication network. The communication may be made, e.g., between UEs, between a UE and a wire connected telephone and/ or between a UE and a server via a Radio Access Network (RAN) and possibly one or more core networks. The wireless communication may comprise various communication services such as voice, messaging, packet data, video, broadcast, etc. The UE/ recipient may further be referred to as mobile telephone, cellular telephone, computer tablet or laptop with wireless capability, etc. The UE in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle- mounted mobile devices, enabled to communicate voice and/ or data, via the radio access network, with another entity, such as another UE or a server.

The wireless communication system may comprise a number of Transmission Points (TP), which are configured for communication over the air interface operating on radio frequencies with any UE within range of the respective TP. Thereby, UEs within a certain geographical area within range of any TP in the wireless communication system may commu- nicate via any TP.

Sometimes, the wireless communication system covers a geographical area which may be divided into cell areas, with each cell area being served by a Transmission Point (TP), or a radio network node e.g., a base station, a Radio Base Station (RBS) or Base Transceiver Station (BTS), which in some networks may be referred to as "eNB", "eNodeB", "NodeB" or "B node", depending on the technology and/ or terminology used. Sometimes, the expression "cell" may be used for denoting the TP/ radio network node itself. However, the cell may also in normal terminology be used for the geographical area where radio coverage is provided by the TP/ radio network node at a base station site. One TP/ radio network node, situated on the base station site, may serve one or several cells. The TPs/ radio network nodes may communicate over the air interface operating on radio frequencies with any UE within range of the respective TP/ radio network node. Further, in some embodiments, a plurality of TPs may serve one cell in some wireless communication systems.

In some radio access networks, several TPs/ radio network nodes may be connected, e.g., by landlines or microwave, to a Radio Network Controller (RNC), e.g., in Universal Mobile Telecommunications System (UMTS). The RNC, also sometimes termed Base Station Controller (BSC), e.g., in GSM, may supervise and coordinate various activities of the plu- ral radio network nodes connected thereto. GSM is an abbreviation for Global System for Mobile Communications (originally: Groupe Special Mobile).

In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)/ LTE- Advanced, radio network nodes, which may be referred to as eNodeBs or eNBs, may be connected to a gateway, e.g., a radio access gateway, to one or more core networks.

Future wireless communication systems will have to face the demand for higher aggregate data rates while being capable of providing reliable communication to many simultaneous users and applications. Such high data rates will be achieved by an increasingly efficient use of the channel's physical resources.

A wireless communication system is considered, in which the service area is covered by a network of TPs, or radio network nodes, that interact with the UEs present in that area, performing communication and coordination tasks. Such network is commonly termed RAN, as has been discussed above.

Each UE may interact with one or more TPs and vice versa. In the present context, the unidirectional radio link from TPs to UEs may be called Down-Link (DL), downstream link or forward link and the unidirectional radio link from the UEs to the TPs may be called Up- Link (UL), upstream link or reverse link. In the Frequency-Division Duplexing (FDD) mode, DL and UL channels use different carrier frequencies. In the Time-Division Duplexing (TDD) mode, the DL and UL channels share the same carrier frequency, but are assigned different time slots. The FDD approach is used over well separated frequency bands in order to avoid interference between uplink and downlink transmissions. In TDD, uplink and downlink traffic are transmitted in the same frequency band, but in different time intervals. The uplink and downlink traffic is thus transmitted separated from each other, in the time dimension in a TDD transmission, possibly with a Guard Period (GP) in between uplink and downlink transmissions. In order to avoid interference between uplink and downlink, for radio network nodes and/ or UEs in the same area, uplink and downlink transmissions between radio network nodes and UEs in different cells may be aligned by means of synchronisation to a common time reference and use of the same allocation of resources to uplink and downlink.

In general, the radio channels from a TP to a UE and from a UE to a TP may be character- ised by different propagation conditions which result in different levels of Channel Quality (CQ). In the FDD mode, each UE independently assesses the CQ of its inbound DL channel and reports the so-obtained Channel Quality Information (CQI) to the TPs through the UL channel. A similar mechanism is used to assess and report the CQ of the UL. Such CQI assessment and reporting technique may sometimes be used also in the TDD mode.

Alternatively, in the TDD mode, thanks to the reciprocity property of wireless channels, it can be assumed that the radio channels from a TP to a UE and from a UE to a TP are characterised by the same propagation conditions. Therefore, the UE and the TP can independently assess the CQ on the inbound channel and exploit such information to adapt to channel conditions on the outbound channel.

The exchanged information between the UEs and the TP is organised in streams. Each stream carries a sequence of messages intended for the same UE. Messages are independently encoded and modulated before transmission. A Rate-Matching (RM) block at the output of the channel encoder performs adaptation of the code block generated by the channel encoder to the number of time-frequency resource elements available for transmission. The scheme of Figure 1 shows the process of encoding and modulation of an information message. In order to provide a suitable level of error protection, the encoder, rate matching and modulator parameters are chosen as a function of the CQ experienced on the TP-UE link. The TP entity responsible for performing such choice is the scheduler. For a given UE-TP channel quality, the scheduler chooses the most suitable code type, rate and modulation order needed to guarantee a sufficient level of protection against errors while providing the required data rate. Multiple Access (MA) schemes permit simultaneous access to a shared channel by several users who wish to independently transmit their information streams. MA requires the adoption of suitable coordination techniques in order to avoid interference among users or other degradation that would result in a decreased reliability or degraded performance. Traditional MA approaches like Frequency-Division Multiple Access (FDMA), Time-Division Multiple Access (TDMA), Space-Division Multiple Access (SDMA) and Code-Division Multiple Access (CDMA) rely on different kinds of partitioning of the channel resources in order to avoid interference, i.e. by frequency, time, space and encoding, respectively. The widely used Orthogonal Frequency-Division Multiplexing (OFDM) modulation technique makes available a set of orthogonal (i.e., independent) time-frequency resource elements that can be assigned to different data streams, resulting in the so-called Orthogonal Frequency-Division Multiple Access (OFDMA) scheme. In mathematical terms, it may be stated that user data streams are made orthogonal in the vector space of transmitted signals by means of these techniques.

In wireless communication systems with a high density of users, within a service area, groups of users may be found that experience similar propagation conditions. In these cases, the CQI values fed back to the RAN by all users in a group will coincide. Therefore, the RAN can group users according to their DL CQ. Messages directed to users in the same group will be encoded using the same code type, rate and modulation parameter values. Due to the increasing number of UEs and to the increasing demands of per-user data rates, future wireless cellular systems will have to provide increased aggregate data rates.

MA schemes are used to make available a shared high-capacity channel to several users simultaneously. A major goal of a MA scheme is to achieving the highest possible aggre- gate data rate or spectral efficiency, while offering the same level of error protection to all streams. One problem with orthogonal multiplexing schemes (FDMA, TDMA, orthogonal CDMA) is that they are in general not optimal in terms of spectrum efficiency. The very orthogonality is a design-limitation, which usually is motivated by the low receiver complexity it exhibits. The idea of hierarchical modulations has been explored and it has been applied in coded image and video transmission. In particular, hierarchical QAM modulations have been adopted in the DVB-T standard for terrestrial broadcasting of digitally encoded video streams. The main goal of these schemes was to simultaneously transmit multiple data streams with unequal error protection features, and in an open-loop, broadcasting system. In the DVB-T standard, two streams: a high-priority stream and a low-priority stream, are multiplexed into one modulated signal. In particular, the high-priority stream is represented by the high-reliability bits in the constellation, and the low-priority stream is represented by the low-reliability bits in the constellation. In a similar fashion, the 3GPP2 standard defines a transmission mode based on hierarchical modulation in which a base modulation layer and a so-called enhancement layer are superimposed to form a higher-order constellation. Here, the purpose of the enhancement layer is to provide a service with enhanced quality to users that experience sufficiently good channel conditions, while providing a lower service quality to users that are able to decode only the base layer.

The characteristics of hierarchical modulations are exploited in order to schedule simultaneous transmission for the two best users in a transmission system with opportunistic scheduling. A "Bit assigner" block is devised in order to decide how to divide the total avail- able transmission rate among the selected users. The protection levels resulting from the bit assignment is, in most cases, unequal. Moreover, the "bit assigner" block is time- invariant, i.e., static.

Superimposed modulations may be obtained by linear combination of multiple modulated signals. The binary labelling of the resulting constellation is induced by the linear combination and cannot be improved without changing the modulation scheme.

Thus there is room for improvements when communicating in a multiple access environment. SUMMARY

It is therefore an object to obviate at least some of the above mentioned disadvantages and to improve the performance in a wireless communication system. This and other objects are achieved by the features of the appended independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, a method is provided in a transmitter in a wireless communica- tion network. The method aims at multiplexing data streams in a multiple access environment. The method comprises transmitting data on a plurality of data streams, to be received by at least one recipient. Further the method comprises obtaining a channel quality estimation. In addition, the method also comprises selecting a number of data streams, based on the obtained channel quality estimation. Also, the method comprises determining a modulation scheme to be utilised for the selected data streams, based on the obtained channel quality estimation. Further, the method also comprises forming a binary label capable of containing the bits of all data streams, and mapping each bit position in such label with a selected data stream. The method also comprises determining the value of the formed binary label by collecting a number of bits from all of the data streams according to the mapping. Furthermore, the method in addition comprises selecting a constellation point in the determined modulation scheme, labelled according to the determined binary label. Additionally, the method furthermore also comprises transmitting data representing the selected constellation point in a time-frequency resource element. In a first possible implementation of the method according to the first aspect, the mapping is made dynamically, such that each bit in the formed binary label is mapped a similar amount of times to each selected data stream within a period comprising a number of symbol intervals comprising at least two symbol intervals. Thereby, a similar error protection level may be achieved on all the selected streams.

In a second possible implementation of the method according to the first aspect, or the first possible implementation of the method according to the first aspect, the mapping is made cyclically in order to achieve similar error protection level on all the selected streams over a period comprising at least two symbol intervals. Thus, by making the mapping cyclically, any arbitrary permutation order of the bit index may be utilised for composing the binary label. In a third possible implementation of the method according to the first aspect, or any previous possible implementation of the method according to the first aspect, the obtained channel quality estimation is related to a channel, indirectly directed to a data stream; and wherein data streams are selected when the difference between the received respective channel quality estimation is smaller than a threshold value.

In a fourth possible implementation of the method according to the first aspect, or any previous possible implementation of the method according to the first aspect, a first data stream and a second data stream are selected. Further, the determined modulation scheme exhibits a plurality of distinct error protection levels for different bits of said binary label, where each distinct error protection level comprises an even number of bits within the formed binary label, where, in every odd symbol interval, for each protection level: a first half of the bits is mapped with the first data stream and a second half of the bits is mapped with the second data stream and in every even symbol interval, the first half of the bits is mapped with the second data stream and the second half of the bits is mapped with the first data stream.

In a fifth possible implementation of the method according to the first aspect, or any previous possible implementation of the method according to the first aspect, wherein K data streams out of a multitude Z≥ Of available data streams are selected. Further, the binary label is formed by collecting m₀ bits from each of said selected data streams and forming the binary label of length m₀ bits. Also, the determined modulation scheme comprises a higher-order extended constellation of 2^m°^K symbols. Furthermore, the binary label is formed such that said data streams have similar error protection level.

In a sixth possible implementation of the method according to the first aspect, or any previous possible implementation of the method according to the first aspect, the transmitter comprises a Transmission Point (TP) and wherein the transmission of data is made in the downlink to be received by at least one recipient, comprising a User Equipment (UE).

In a seventh possible implementation of the method according to the sixth possible implementation of the method according to the first aspect, the transmitter comprises a UE, and wherein the transmission of data is made in the uplink from the same transmission circuit, to be received by at least one recipient comprising a TP.

In an eighth possible implementation of the method according to the first aspect, or any previous possible implementation of the method according to the first aspect, the transmit- ter is configured for operation in TDD mode and the action of obtaining the channel quality estimation comprises receiving a signal from the recipient on the reverse link and estimating the channel quality of the received signal. In a ninth possible implementation of the method according to the first aspect, or any previous possible implementation of the method according to the first aspect, the transmitter is configured for operation in FDD mode or in TDD mode and the action of obtaining the channel quality estimation comprises receiving the channel quality estimation from the recipient.

In a second aspect, a transmitter is provided for data transmission in a wireless communication network, wherein the transmitter is configured for multiplexing data streams in a multiple access environment. The transmitter comprises a transmitting circuit, configured for transmitting data on a plurality of data streams, to be received by at least one recipient and also configured for transmitting data representing a constellation point in a time-frequency resource element. Further, the transmitter also comprises a receiving circuit, configured for obtaining a channel quality estimation. Additionally, the transmitter furthermore comprises a processor, configured for selecting a number of data streams based on the obtained channel quality estimation; and also configured for determining a modulation scheme to be utilised for the selected data streams, based on the obtained channel quality estimation related to the selected data streams. Furthermore the processor is configured for forming a binary label capable of comprising the bits of all data streams, and mapping each bit position in such label with a selected data stream. Additionally the processor is also configured for determining the value of the formed binary label by collecting a number of bits from each of the data streams according to the mapping. Also, the processor furthermore also in addition is configured for selecting a constellation point in the determined modulation scheme, labelled according to the determined binary label.

In a first possible implementation of the second aspect, the processor is further configured for performing the mapping dynamically, such that each bit in the formed binary label is mapped a similar amount of times to each selected data stream within a period comprising at least two symbol intervals.

In a second possible implementation of the second aspect, or the first possible implemen- tation of the second aspect, the processor may be further configured for performing the mapping cyclically, in order to achieve similar error protection level on the selected streams over a period comprising at least two symbol intervals. In a third possible implementation of the second aspect, or any previous possible implementation of the second aspect, the obtained channel quality estimation is related to a channel, indirectly directed to a data stream. The processor is further configured for select- ing data streams when the difference between the received respective channel quality estimation is smaller than a threshold value.

In a fourth possible implementation of the second aspect, or any previous possible implementation of the second aspect, the processor is further configured for selecting a first data stream and a second data stream. The processor is also configured for determining a modulation scheme, which exhibits a plurality of distinct error protection levels for different bits of said binary label, where each distinct error protection level comprises an even number of bits within the binary label, where, in every odd symbol interval, for each respective protection level: a first half of the bits is mapped with the first data stream and a second half of the bits is mapped with the second data stream and in every even symbol interval, the first half of the bits is mapped with the second data stream and the second half of the bits is mapped with the first data stream.

In a fifth possible implementation of the second aspect, or any previous possible implemen- tation of the second aspect, the processor is further configured for selecting data streams out of a multitude Z≥ K of available data streams. Further, the processor is also configured for forming the binary label by collecting m₀ bits from each of said K data streams and forming the binary label of length m₀ K bits. In addition, the processor is also configured for determining a modulation scheme which comprises a higher-order extended constellation of 2^m°^K symbols and wherein the processor is further configured for forming the binary label such that said data streams have similar error protection level.

In a sixth possible implementation of the second aspect, or any previous possible implementation of the second aspect, the transmitter comprises a TP, and wherein the transmis- sion of data is made in the downlink to be received by at least one recipient, which comprises a UE.

In a seventh possible implementation of the second aspect, or any previous possible implementation of the second aspect, the transmitter comprises a UE, and wherein the transmission of data is made in the uplink to be received by at least one recipient, which comprises a TP. In an eighth possible implementation of the second aspect, or any previous possible implementation of the second aspect, the transmitter is configured for operation in TDD mode and also configured for obtaining the channel quality estimation by receiving a signal from the recipient on the reverse link and estimating the channel quality of the received signal.

In a ninth possible implementation of the second aspect, or any previous possible implementation of the second aspect, the transmitter is configured for operation in FDD mode or in TDD mode and further configured for obtaining the channel quality estimation by receiving the channel quality estimation from the recipient.

In a further implementation of the first aspect and/ or the second aspect, a computer program comprising program code is provided, for performing a method according to the first aspect or any previous possible implementation of the first aspect, for multiplexing data streams in a multiple access environment when the computer program is loaded into a processor of the transmitter according to the second aspect, or any previous possible implementation of the second aspect.

In yet a further implementation of the first aspect and/ or the second aspect, a computer program product comprising a computer readable storage medium storing program code thereon for in a wireless communication system for multiplexing data streams in a multiple access environment. The program code comprising instructions for executing a method comprising transmitting data on a plurality of data streams, to be received by at least one recipient. Further the method comprises obtaining a channel quality estimation. Also, the method further comprises selecting a number of data streams, based on the obtained channel quality estimation. In addition, the method furthermore comprises determining a modulation scheme to be utilised for the selected data streams, based on the obtained channel quality estimation. Also, the method comprises forming a binary label capable of containing the bits of all data streams and mapping each bit position in such label with a selected data stream. Furthermore, the method also comprises determining the value of the formed binary label by collecting a number of bits from all of the data streams according to the mapping. The method additionally comprises selecting a constellation point in the determined modulation scheme, labelled according to the determined binary label. In further addition, the method comprises transmitting data representing the selected constellation point in a time-frequency resource element.

According to a third aspect, a method is provided in a recipient in a wireless communication network, for receiving at least one multiplexing data stream in a multiple access envi- ronment. The method comprises receiving data on at least one data stream transmitted by a transmitter. Further the method also comprises determining a modulation scheme to be utilised for the received data stream, based on estimated channel quality or on transmission parameter signalling information received from the transmitter. The method further comprises receiving data representing a constellation point in a time-frequency resource element. Also, the method comprises demapping the received data by determining which bits in a binary label, corresponding to the constellation point that is associated with the data stream. In a first possible implementation of the third aspect, the recipient is operating in TDD mode.

In a second possible implementation of the third aspect, or any previous possible implementations of the third aspect, the recipient is operating either in FDD mode or in TDD mode and the method further comprises: estimating a channel quality related to a channel associated with the received data stream. In addition the method comprises transmitting the estimated channel quality, to be received by the transmitter.

In a third possible implementation of the third aspect, or any previous possible implementa- tions of the third aspect, the recipient comprises a UE and the reception is made in the downlink of data transmitted by the transmitter, which comprises a TP.

In a fourth possible implementation of the third aspect, or any previous implementation of the third aspect, the recipient comprises a TP and the reception is made in the uplink of data transmitted by the transmitter, which comprises a UE.

According to a fourth aspect, a recipient in a wireless communication network is provided, configured for receiving data on at least one data stream, transmitted by a transmitter and also configured for receiving data representing a constellation point in a time-frequency resource element. The recipient also comprises a processor, configured for determining a modulation scheme to be utilised for the received data stream and additionally configured for demapping the received data by determining which bits in a binary label, corresponding to the constellation point, which have been associated with the data stream. In a first possible implementation of the fourth aspect, the recipient is configured for operation in TDD mode. In a second possible implementation of the fourth aspect, or any previous implementation of the fourth aspect, the recipient is configured for operation either in FDD mode or in TDD mode. The processor is further configured for estimating a channel quality related to a channel associated with the received data stream. Further, the recipient also comprises a transmitting circuit, configured for transmitting the estimated channel quality, to be received by the transmitter.

In a third possible implementation of the fourth aspect, or any previous implementation of the fourth aspect, the recipient comprises a UE; the reception is made in the downlink of data transmitted by the transmitter, which comprises a TP.

In a fourth possible implementation of the fourth aspect, or any previous implementation of the fourth aspect, the recipient comprises a TP; the reception is made in the uplink of data transmitted by the transmitter, which comprises a UE.

In yet a possible implementation of the third aspect and/ or the fourth aspect, a computer program is provided, comprising program code for performing a method according to the third aspect, or any possible implementation of the third aspect, for receiving at least one multiplexing data stream in a multiple access environment when the computer program is loaded into a processor of a recipient according to the fourth aspect, or any possible implementation of the fourth aspect.

In yet a further possible implementation of the third aspect and/ or the fourth aspect, a computer program product is provided, comprising a computer readable storage medium storing program code thereon for receiving at least one multiplexing data stream in a multiple access environment in a wireless communication system. The program code comprises instructions for executing a method according to the third aspect, or any possible implementation of the third aspect, comprising receiving data on at least one data stream, transmitted by a transmitter. Also the method comprises determining a modulation scheme to be utilised for the received data stream, based on estimated channel quality or on transmission parameter signalling information received from the transmitter. Further, the method additionally comprises receiving data representing a constellation point in a time- frequency resource element. The method also comprises demapping the received data by determining which bits in a binary label, corresponding to the constellation point, associ- ated with the data stream. Thanks to the herein described aspects, it is possible to provide an overloaded multiple access scheme wherein a plurality of independent data streams are combined onto the same time-frequency resource element, simultaneously transmitting multiplexed streams without requirement of signal bandwidth and providing the same or similar protection level for the transmitted data streams. Thereby, the data transmission rate may be increased within the wireless communication system without signal bandwidth expansion and without exposing the data streams for unequal protection levels. Thus an improved performance within a wireless communication system is provided. Other objects, advantages and novel features of the aspects of the invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are described in more detail with reference to attached drawings in which:

Figure 1 is an illustration of message encoding and modulation according to prior art.

Figure 2 is a block diagram illustrating a wireless communication system according to some embodiments.

Figure 3A is a block diagram illustrating a transmitter according to some embodiments. Figure 3B is a block diagram illustrating a recipient according to some embodiments.

Figure 4A illustrates a constellation with binary labelling and an example of stream-to- label mapping.

Figure 4B illustrates information of the binary input channels as a function of signal to noise ratio in a certain constellation, according to an example.

Figure 4C illustrates a constellation with binary labelling and an example of stream-to- label mapping.

Figure 4D illustrates information of the binary input channels as a function of signal to noise ratio in a certain constellation, according to an example.

Figure 4E illustrates a constellation with binary labelling and an example of stream-to- label mapping.

Figure 4F illustrates information of the binary input channels as a function of signal to noise ratio in a certain constellation, according to an example. Figure 4G illustrates information of the binary input channels as a function of signal to noise ratio in a certain constellation, according to an example.

Figure 5A illustrates a constellation with binary labelling and a corresponding signal set partitioning according to a certain bit.

Figure 5B illustrates a constellation with binary labelling and a corresponding signal set partitioning according to a certain.

Figure 5C illustrates a constellation with binary labelling and a corresponding signal set partitioning according to a certain bit.

Figure 5D illustrates a constellation with binary labelling and a corresponding signal set partitioning according to a certain bit.

Figure 6 illustrates a dynamic stream-to-label mapping according to an embodiment.

Figure 7 is a flow chart illustrating a method in a transmitter according to an embodiment.

Figure 8 is a block diagram illustrating a transmitter according to an embodiment. Figure 9 is a flow chart illustrating a method in a recipient according to an embodiment.

Figure 10 is a block diagram illustrating a recipient according to an embodiment.

DETAILED DESCRIPTION

Embodiments of the invention described herein are defined as a transmitter and a method in a transmitter, a recipient and a method in the recipient which may be put into practice in the embodiments described below. These embodiments may, however, be exemplified and realised in many different forms and are not to be limited to the examples set forth herein; rather, these illustrative examples of embodiments are provided so that this disclosure will be thorough and complete.

Still other objects and features may become apparent from the following detailed description, considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the herein disclosed embodiments, for which reference is to be made to the appended claims. Further, the drawings are not necessarily drawn to scale and, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. Figure 2 is a schematic illustration over a wireless communication system 100 comprising a transmitter 110 communicating with a first recipient 120-1 in a first stream 130-1 and with a second recipient 120-2 in a second stream 130-2.

The wireless communication system 100 may at least partly, for example be based on radio access technologies such as, e.g., 3GPP LTE, LTE-Advanced, Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications (originally: Groupe Special Mobile) (GSM)/ Enhanced Data rate for GSM Evolution (GSM/EDGE), Wideband Code Division Multiple Access (WCDMA), Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single- Carrier FDMA (SC-FDMA) networks, Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), High Speed Packet Access (HSPA) Evolved Universal Terrestrial Radio Access (E-UTRA), Universal Terrestrial Radio Access (UTRA), GSM EDGE Radio Access Network (GERAN), 3GPP2 CDMA technologies, e.g., CDMA2000 1 x RTT and High Rate Packet Data (HRPD), just to mention some few options. The expressions "wireless communication network", "wireless communication system" and/ or "cellular telecommunication system" may within the technological context of this disclo- sure sometimes be utilised interchangeably. Further, the wireless communication network 100 may comprise a cellular network or a non-cellular network according to different embodiments.

The wireless communication system 100 may be configured for communication in a Fre- quency Division Duplex (FDD) and/ or Time Division Duplex (TDD) environment, according to different embodiments.

The purpose of the illustration in Figure 2 is to provide a simplified, general overview of the wireless communication system 100 and the involved methods and nodes, such as the transmitter 1 10 and recipients 120 herein described, and the functionalities involved. The method and wireless communication system 100 will subsequently, as a non-limiting example, be described in a 3GPP LTE/ LTE-Advanced environment, but the embodiments of the disclosed method and wireless communication system 100 may be based on another access technology such as, e.g., any of the above already enumerated. Thus, although embodiments of the invention may be described based on, and using the lingo of, 3GPP LTE systems, it is by no means limited to 3GPP LTE, LTE- Advanced etc. The transmitter 1 10 may according to some embodiments be configured for downlink transmission and may be referred to, respectively, as e.g., a Transmission Point (TP), a base station, NodeB, evolved Node Bs (eNB, or eNodeB), base transceiver station, Access Point Base Station, base station router, Radio Base Station (RBS), micro base station, pico base station, femto base station, Home eNodeB, sensor, beacon device, relay node, repeater or any other network node configured for communication with the recipient 120 over a wireless interface, depending, e.g., of the radio access technology and/ or terminology used. The recipient 120 may correspondingly be represented by, e.g. a User Equipment (UE), a wireless communication terminal, a mobile cellular phone, a Personal Digital Assistant (PDA), a wireless platform, a mobile station, a tablet computer, a portable communication device, a laptop, a computer, a wireless terminal acting as a relay, a relay node, a mobile relay, a Customer Premises Equipment (CPE), a Fixed Wireless Access (FWA) nodes or any other kind of device configured to communicate wirelessly with the transmitter 1 10, according to different embodiments and different vocabulary.

However, according to some embodiments, the situation may as well according to some embodiments be the opposite, such that the transmitter 1 10 may be configured for uplink transmission and may be referred to, respectively, as e.g., a User Equipment (UE), a wireless communication terminal, a mobile cellular phone, a Personal Digital Assistant (PDA), a wireless platform, a mobile station, a tablet computer, a portable communication device, a laptop, a computer, a wireless terminal acting as a relay, a relay node, a mobile relay, a Customer Premises Equipment (CPE), a Fixed Wireless Access (FWA) nodes or any other kind of device configured to communicate wirelessly with the recipient 120, according to different embodiments and different vocabulary.

Consequently, according to some such embodiments, the recipient 120 may correspondingly be represented by, e.g. a Transmission Point (TP), a base station, NodeB, evolved Node Bs (eNB, or eNodeB), base transceiver station, Access Point Base Station, base station router, Radio Base Station (RBS), micro base station, pico base station, femto base station, Home eNodeB, sensor, beacon device, relay node, repeater or any other network node configured for communication with the transmitter 1 10 over a wireless interface, depending, e.g., of the radio access technology and/ or terminology used.

It is to be noted that the illustrated network setting of one transmitter 1 10, represented by a transmission point and two recipients 120-1 , 120-2, represented by a respective UE in Fig- ure 2 is to be regarded as a non-limiting example of an embodiment only. The wireless communication system 100 may comprise any other number and/ or combination of transmitters 1 10 and/ or recipients 120. A plurality of recipients 120 and another configuration of transmitters 1 10 may thus be involved in some embodiments.

Thus whenever "one" or "a/ an" recipient 120 and/ or transmitter 1 10, respectively, is referred to in the present context, a plurality of recipients 120 and/ or transmitters 1 10 may be involved, according to some embodiments. The herein disclosed method relates to a non-orthogonal multiple access scheme, which may be referred to as Constellation-Expansion Multiple Access (CEMA), where higher- order modulations may be used to combine multiple independent data streams (coded or un-coded) on a set of time-frequency resources, thus achieving higher aggregate data rates.

It would be beneficial if non-orthogonal schemes would be developed that achieve higher aggregate spectral efficiencies with controlled increase in complexity. Hierarchical modulations and superimposed modulations may perhaps be the promising transmission techniques that form a starting point for developing an improved method.

Embodiments herein disclosed do not exhibit hierarchical characteristics. In fact, according to this method, streams may be grouped based on their CQI values and transmitted with equal protection levels in a given set of time-frequency resources. Therefore, no hierarchy may be established among streams in some embodiments.

Some embodiments herein disclosed, instead, may use a dynamic stream-to-label mapping that may achieve equal or similar error protection for all streams while featuring robustness characteristics to channel and other hardware impairments. However, some embodiments herein disclosed, instead, may use higher-order constellations in a native fashion. The constellation's binary labelling can be arbitrarily chosen to improve the system performance.

Thus it is herein disclosed a multiplexing method in a multiuser downlink scenario with channel-quality feedback. The method may in some embodiments comprise concurrently transmitting Z downlink data streams wherein the method using a single time-frequency resource element, and said method embodiment may comprise the steps of selecting K data streams out of a multitude Z where Z≥ K of available data streams based on the channel-quality feedback information. Further, some method embodiments may comprise collecting m₀ bits from each of said the K data streams and forming a composite binary label of length m₀ K bits. Furthermore, the method embodiments may also comprise se- lecting the constellation point in a higher-order extended constellation of 2^m°^K symbols, labelled by said composite binary label. Further, the method in some embodiments may comprise transmitting said selected constellation point in a time-frequency resource element. According to some embodiments, the K data streams are selected such that K selected data streams are associated with the same, or similar channel-quality streams, and where said forming a composite binary label may be done such that said data streams have similar error protection.

Embodiments disclosed herein may apply to the downlink of wireless communication systems 100. The disclosed CEMA scheme may comprise an overloaded multiple-access scheme in which several independent data streams are combined onto the same time- frequency resource elements. Combining may be made possible by using higher-order modulations. The multiplexed streams may then simultaneously be transmitted on the same time-frequency resources without requiring expansion of the signal bandwidth. Overloading is a paradigm according to which several data streams can be multiplexed onto the same time-frequency resource elements, thus resulting in increased data rates without requiring signal bandwidth expansion, according to some embodiments.

In the transmission of a single data stream 130, according to some embodiments, the coded bits may be transmitted using a modulation whose signals may belong to constella- tion χ₀ which may comprise ₀ complex signals. Its modulation order may be defined as m₀ = log₂ M₀ and it may coincide with the number of bits associated to each modulation symbol. Each symbol in χ₀ may be associated with a binary label (ZJ₁₍ ... , b_mo) e {0,l}^m° - In the following, χ₀ will be referred to as the base constellation and m₀ may be referred to as the base order.

Using higher-order modulations, K streams can be combined and simultaneously transmitted using the same time-frequency resources, thus not requiring longer transmission times or signal bandwidths. In order to accommodate the coded information of all K streams without increasing the number of time-frequency resources, it may be an advantage to dis- pose of a larger constellation whose order may be m = Km₀ in some embodiments. The size of the new constellation may therefore become: \χ\ = 2^m = 2^m°^K (1 ) and it can be thought as the result of the expansion of the base constellation χ₀ into a larger constellation χ , the expanded constellation. The signals of χ may be labelled with binary vectors (ZJ₁₍ ... , b_m) e {0,l}^m. In Figure 3A, a general scheme of a CEMA transmitter 1 10 according to an embodiment is shown. Exploiting the CQI information provided by the scheduler, a stream selection block may select K messages with same or similar CQI from the set of all Z≥ K messages available in input. Each of the K messages may then be independently encoded and rate matching is applied. A dynamic stream-to-label mapping block computes the symbol label of the constellation point as a function of the coded bits. Finally, in the constellation point selection block, the symbol label may be used to select the corresponding symbol from the expanded constellation χ and to generate the corresponding modulated signal.

The constellation symbol selection block of Figure 3A may generate a sequence of com- plex modulation symbols selected from the expanded constellation χ according to the symbol label. The disclosed CEMA scheme does not impose any restriction on the constellation.

Binary labelling of constellation points is usually performed according to the Gray rule, which results in the following property: pairs of binary labels associated to constellation points whose Euclidean distance is minimal differ only in one bit.

In Figure 3B, a scheme of an embodiment of a k-t CEMA receiver 120 is shown. A detector block may compute the (soft or hard) estimates of the coded bits and feed them into the label-to-stream demapping block. This block may compute the estimates of coded bits intended for the k-th receiver 120 and may feed them into the inverse RM and channel decoder block, which finally may compute the estimates of information bits.

Figure 4A illustrates a constellation scheme 400, 16 Phase-Shift Keying (PSK), with con- stellation points 410, associated with a respective binary labelling 420 and an example of stream-to-label mapping. The binary label 420 comprises four bits b1 , b2, b3, b4 in this non-limiting example. In other embodiments, an arbitrary number n of bits may be comprised in the binary label 420, where 0 < n <∞. Further, an arbitrary number K of streams 130-1 , 130-2 may be involved in some embodiments, where 0 < K<∞. The illustrated constellation 400 is an example of static stream-to-label mapping: the two rightmost bits of the binary label 420 are assigned to stream 1 130-1 (normal) and the two leftmost bits of the binary label are assigned to stream 2 130-2 (embossed). Figure 4B illustrates information of the binary input channels resulting from 16 PSK decomposition.

A characteristic which is common to most modulation schemes, e.g. in 16 PSK illustrated in Figure 4A, is that different bits b1 , b2, b3, b4 convey different amounts of information, thus resulting in different levels of protection against errors. This effect will be further explained in detail in connection with the presentation of Figures 5A-5D.

In the 16PSK modulation 400, there are three different levels of protection. This characteristic is shown in Figure 4B, where the quantity of information carried by each of the four binary-input channels resulting from 16 PSK decomposition is plot against a Signal-to- Noise Ratio (SNR or S/N). This quantity will herein be referred to as the protection level of each bit b1 , b2, b3, b4 in the binary label 420.

The herein used measurement a Signal-to-Noise Ratio may be exchanged for any similar ratio related to a comparison between the level of a desired signal to the level of background noise, such as e.g. Signal-to-lnterference-plus-Noise Ratio (SINR), Signal-to-Noise- plus-lnterference Ratio (SNIR), Signal-to-lnterference Ratio (SIR), Signal, Noise and Distortion (SINAD), Signal-to-Quantization-Noise Ratio (SQNR), Carrier-to-Noise Ratio (C/N), Noise to Signal Ratio (NSR), or any similar measurement.

Figure 4C illustrates a 16-APSK constellation 400 with binary labelling specified in the DVB-S2 standard.

Amplitude-Phase Shift Keying (APSK) type constellations 400 are utilised e.g. in the DVB- S2 standard. In these constellations 400, complex symbols (points) are placed on a number of concentric rings. The case of one ring with M equally spaced symbols results in M- PSK modulations, such as 16 PSK or 32 PSK to mention a couple of arbitrary examples.

In the 16APSK constellation 400, there are two different levels of protection, as illustrated in Figure 4D. The shape of APSK modulations 400 as illustrated in Figure 4A and 4C respectively, may result in a low Peak-to-Average Power Ratio (PAPR), a nice characteristic for power- constrained wireless communication systems 100. Such feature may be expected to be relevant for future wireless systems 100 where a large number of low-power access points are deployed.

Figure 4E illustrates an embodiment of a 16 Quadrature Amplitude Modulation (QAM) constellation 400 with Gray labelling and an example of stream-to-label mapping. The case of square /W-QAM constellations 400 may be particularly relevant due to their wide adoption. Square /W-QAM constellations 400 may have size M = 2^m, with m any even positive integer. In general, /W-QAM modulations 400 are sets of complex points defined as χ = {±s, ± JSQ}. Here, j = V-ϊ , and s,, s_Q are any positive odd integers < M. Figure 4E shows a 16-QAM constellation 400 with Gray labelling and a possible stream-to-label map- ping scheme. The two rightmost bits b1 , b2 of the binary label 420 are assigned to Stream

1 130-1 (normal) and the two leftmost bits b3, b4 of the binary label 420 are assigned to Stream 2 130-2 (embossed).

In a square /W-QAM constellation 400 whose order is m = log₂ M, there are m/2 different levels of protection. This characteristic is shown in Figure 4F for 16-QAM and in Figure 4G for 256-QAM, where the quantity of information carried by each of the m binary-input channels resulting from QAM decomposition is plot against SNR. For a fixed SNR value, m/

2 distinct protection levels are available. Figures 5A-5D illustrate how the 4 bit-positions of the label 420 are represented in the constellation 400 of Figure 4E. In this non-limiting example, the constellation 400 comprises a 16 QAM constellation. Intuitively, the information conveyed through the binary channels corresponding to bits in position i = 1,2 will be different from the information conveyed through the bits in position i = 3,4. The Euclidean distances are different and a re- ceiver performance will be different, depending which bit b1 , b2, b3, b4 is evaluated.

Regard the constellation point 410 having the binary label 420 with the value 1011 . In case the transmission is distorted and therefore misinterpreted by the recipient 120 as representing the constellation point 410 of value 1000, both of the two left bits b3, b4 yet has the same value, 1 and 0 respectively. However, the two rightmost bits, originally having the value 1 and 1 respectively, both become misinterpreted as 0 and 0. Thus, some constellation points 410 are grouped such that a minor disturbance during transmission leading to misinterpretation of the constellation point 410 for another neighbouring constellation point 410 does not influence the interpretation of the bits in some positions of the label 420. However, some bits such as b2 =1 in Figure 5C and b1 =1 in Figure 5D are not grouped together in the constellation 400, why a minor disturbance may lead to a misinterpretation on the receiver side of those bits.

Figure 6 illustrates a dynamic stream-to-label mapping block. In order to obtain equal or close-to-equal protection levels for all streams 130 and for all combinations of parameters m₀ and K, suitable labelling approaches may be devised.

The dynamic stream-to-label mapping block in Figure 6 associates the m₀ coded bits of each stream 130 to the m bits of the symbol label 420 according to a mapping that changes from symbol to symbol with a predefined period of Q symbols.

Dynamic stream-to-label mapping can be specified by means of a set of Q>1 permutations U_q, q = 1, ... , Q, of size m. At each symbol interval, a different permutation is applied. After Q symbol intervals, the first permutation may be used again and the sequence may be repeated.

A permutation U_q: i >→ U_{q i} can be defined using a vector of unique integers in [l, m] with the following interpretation: the H input element to the permutation block is moved to position U_{q i} at its output. The whole set of Q permutations may then be specified using a m x Q mapping matrix with its qth column corresponding to permutation Π^.

To avoid ambiguity, it may be specified that the input bits to the stream-to-label mapping are fed into the permutation block as follows, see Figure 6: β_μ = b_i:i with index i = |μ/?η₀1 and index j = 1 + (μ— 1) mod m₀. Here, (β , ... , /?_m) indicates the input vector of the permutation block. Index First symbol

interval

Stream 1 1 1 (weak)

130-1 2 2 (mid)

Stream 2 3 3 (strong)

130-2 4 4 (strong)

Table 1

Table 1 disclose a stream to label mapping for the 16 PSK constellation 400 with two streams 130-1 , 130-2 of Figure 4A. Thus the disclosed non-limiting example may corre- spond to the constellation 400 of Figure 4A. The stream-to-label mapping is not changing from symbol to symbol in this case i.e., it is not dynamic, therefore its period is Q=1. An example of the resulting mapping matrix is shown in Table LThis is example describes a stream-to-label mapping that is not part of the described method, since it is not dynamic. Moreover, it does not provide similar error protection to all streams 130-1 , 130-2. Instead, it is illustrating problems associated with static mapping according to prior art.

From Figure 4B it may be noticed that, for a fixed SNR, the 16 PSK constellation features three distinct protection levels (strong, mid and weak). The two highly protected (strong) bits b3, b4 are both assigned to stream 2 130-2, while the two weaker bits b1 , b2 are as- signed to stream 1 130-1 . This static stream-to-label assignment is clearly unequal in terms of error protection. It may also be observed that it is not possible to obtain equal stream protection by means of static mappings. Instead it may be noticed that a simple dynamic mapping of period Q = 2 achieves equal protection for both streams 130-1 , 130-2. It is shown in Table 2.

Table 2 Table 2 disclose Equal-protection stream to label mapping for the 16PSK constellation 400 with two streams 130-1 , 30-2. For the 16APSK modulation 400 of Figure 4C, whose protection levels are shown in Figure 4D, the situation is rather different: only two distinct protection levels are featured and thus it is possible to perform an equal-protection mapping with period 1 of two information streams 130-1, 130-2. For the two-stream case, similar considerations apply for square M-QA modulations. Figure 4E shows a 16QAM constellation. From Figure 4F it may be noticed that this constellation 400 exhibits two distinct protection levels.

Table 3

Table 3 disclose a Stream-to-label mapping for the 16QAM constellation with two streams 130-1 , 130-2 of Figure 4E.

This mapping clearly results in unequal protection, since all the strong bits are assigned to stream 2 30-2, while stream 1 130-1 gets all the weak bits. However, an alternative equal- protection mapping can be designed, shown in Table 4A and/or Table 4B. Each stream 30-1 , 130-2 may use one strong bit, bit 3 or bit 4, and one weak bit, bit 1 or bit 2 in the illustrated embodiment. Index First symbol

interval

Stream 1 1 1 (weak)

130-1 2 3 (strong)

Stream 2 3 2 (weak)

130-2 4 4 (strong)

Table 4A

Table 4A discloses an equal-protection mapping for the 16-QAM constellation with two streams 130-1 , 130-2 according to an embodiment. This is a non-dynamic embodiment not part of the herein presented method.

Thus it is possible, in some cases, to design static mappings with equal protection. However, when additional channel impairments are taken into account, such as e.g. fading that might act independently on the I and Q components as a result of independent l/Q inter- leaving, and other propagation phenomena like beam depolarization and hardware impairments (nonlinearities, l-Q imbalance, signal offsets in the analogue sections and in the A/D conversion stages, etc.), the information characteristic of the considered modulations become different from the ideal characteristics shown in Figure 4B, Figure 4D, Figure 4F and Figure 4G. As a result, such static mappings likely may become unequal.

For these reasons, the non-dynamic stream-to-label mapping of prior art is exchanged for a general dynamic mapping rule in our method, able to guarantee equal protection independently of the number of streams 130-1 , 130-2 and of the constellation 400 while adding further robustness with respect to the aforementioned impairments.

Table 4B discloses a dynamic equal-protection mapping for the 16-QAM constellation with two streams 130-1 , 130-2 according to an embodiment. Index First symbol Second symbol

interval interval

Stream 1 1 1 {weak 1) 1 (weak 2)

130-1 2 3 (strong 1 ) 3 (strong 2)

Stream 2 3 2 (weak 2) 2 (weak 1 )

130-2 4 4 (strong 2) 4 (strong 1 )

Table 4B

The stream-to-label mappings shown in Table 1 , Table 3 and Table 4A are not dynamic, since they do not change from symbol to symbol, in other words, their period is Q=1. In general, mapping K streams onto an expanded constellation with P protection levels requires using a dynamic labelling, i.e., a labelling which changes from symbol to symbol with period Q>1. Thus the illustrated static stream-to-label mappings shown in Table 1 , Table 3 and Table 4A are disclosed only for illustrating disadvantages of the prior art mapping. Instead, according to embodiments herein, a general dynamic mapping is disclosed that achieves equal protection levels on all streams 130-1 , 130-2 for all values of K and m. The mapping has period Q = K and it is represented in Table 5, according to an embodiment.

Here, each bit b1 , b2 bn of the expanded constellation label is cyclically assigned to the K streams. As a result, each stream enjoys the error protection level provided by each bit for a fraction 1/K of the total transmission time: averaging over a message transmission, all streams are equally protected.

(ndex Symbol interval

1 2 ... Q = K

1 1 m₀ + 1 ... (K - l)m₀+1 ώ

_*- ... ... ...

CO m₀ m₀ 2m₀ Km₀

... ... ...

(iT - l)m₀ + l (tf - l)m₀ + 1 1 (K - 2)m₀ + 1

6

o

...

to ifm₀ Km₀ m₀ ... (ftT - l)m₀

Table 5

Table 5 illustrates a general equal-protection mapping. Equal-protection mapping schemes with period Q shorter than K can be found in some embodiments. The mapping shown in Table 4B for 16-QA is an example that can be generalised as follows: consider the case of two information streams being multiplexed over an expanded constellation of type M-QAM. In this case, it may be observed that, for a given SNR, bit 2t— 1 and bit 2i (i = 1, ... ,m/2 ) exhibit the same error protection level, see Figure 4G for the 256-QAM case. Thus, assigning bits in odd positions to one stream 130- 1 and bits in even positions to the other stream 130-2 results in an equal-protection mapping. This mapping is shown in Table 6, where it is extended to Q = 2 symbols for the aforementioned reasons, yielding a dynamic stream-to-label mapping.

Index Symbol interSymbol interval 1 val 2

1 1 2

Stream 1 2 3 4

130-1 ... ... ...

m₀ m— 1 m

m₀ + 1 2 1

Stream 2 4 3

130-2 ...

2m₀ m m - 1

Table 6

After permutation, the symbol label is computed by converting the binary vector (¾, ... , u_m) into an integer value as follows:

Furthermore, some embodiments disclosed herein may be applicable in all bit-interleaved coded modulation transmission systems, possibly combined with OFDM and MIMO transmission.

Figure 7 is a flow chart illustrating embodiments of a method 700 in a transmitter 1 10 in a wireless communication system 100. The method 700 aims at providing multiplexing data streams 130-1 , 130-2 in a multiple access environment by providing dynamic stream-to- label mapping.

The transmitter 1 10 may comprise a Transmission Point (TP) in some embodiments; transmission of data may be made in the downlink to be received by at least one recipient 120, comprising a User Equipment (UE). However, in some embodiments, the transmitter 110 may comprise a UE, and the transmission of data may be made in the uplink from the same transmission circuit, to be received by at least one recipient 120, comprising a TP.

The wireless communication network 100 may be based on 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) in some embodiments. In some such embodi- merits, the transmitter 1 10 may comprise an evolved node B (eNodeB). Further, the wireless communication system 100 may be based on FDD or TDD in different embodiments.

To appropriately provide multiplexing data streams 130-1 , 130-2, the method 700 may comprise a number of actions 701 -708.

It is however to be noted that any, some or all of the described actions 701-708, may be performed in a somewhat different chronological order than the enumeration indicates, be performed simultaneously or even be performed in a completely reversed order according to different embodiments. Further, it is to be noted that some actions may be performed in a plurality of alternative manners according to different embodiments, and that some such alternative manners may be performed only within some, but not necessarily all embodiments. The method 700 may comprise the following actions: Action 701

Data is transmitted on a plurality of data streams 130-1 , 130-2, to be received by at least one recipient 120. The plurality of data streams 130-1 , 130-2 may comprise e.g. Z data streams 130-1 , 130-2, where 0 < Z <∞. One or more data streams 130-1 , 130-2 may be associated with one or more recipients 120.

Action 702

A channel quality estimation is obtained.

In some embodiments wherein the transmitter 1 10 is operating in Time Division Duplex (TDD) mode, the channel quality may be estimated by receiving a signal from the recipient 120 on the reverse link and estimating the channel quality of the received signal.

In some other embodiments, wherein the transmitter 1 10 is operating in either Frequency Division Duplex (FDD) mode or in Time Division Duplex (TDD) mode, the channel quality estimation may comprise receiving the channel quality estimation from the recipient 120.

The channel quality estimation, or Channel Quality Information (CQI) may be related to a channel involving the transmitter 1 10 and the recipient 120, and may be indirectly directed to a data stream 130-1 , 130-2 in some embodiments. Action 703

A number K of data streams 130-1 , 130-2 is selected, based on the obtained 702 channel quality estimation, where 0 < K≤ Z. In some embodiments, data streams 130-1 , 130-2 may be selected when the difference between the obtained 702 respective channel quality estimation, e.g. CQI is smaller than a threshold value. Such threshold value may be predetermined or configurable.

Action 704

A modulation scheme 400 to be utilised for the selected 703 data streams 130-1 , 130-2 may be determined, based on the obtained 702 channel quality estimation.

Such modulation scheme 400 may comprise e.g. APSK constellations, or QAM constellations in different embodiments.

Action 705

A binary label 420 capable of containing bits b1 , b2, bn of all K data streams 130-1 , 130-2 is formed, and each bit position in such label 420 is mapped with a selected 703 data stream 130-1 , 130-2.

The mapping is made dynamically, such that each bit b1 , b2, bn in the formed binary label 420 is mapped a similar or equal amount of times to each selected 703 data stream 130-1 , 130-2 within a period comprising at least two symbol intervals. In some embodiments, each bit b1 , b2, bn in the formed binary label 420 may be mapped a similar or equal amount of times to each selected 703 K data stream 130-1 , 130-2 within a period comprising a number n of symbol intervals equal to the number K of selected 703 data streams 130-1 , 130-2.

The mapping may be made cyclically in order to achieve similar error protection level on all the selected 703 streams 130-1 , 130-2 over a period comprising at least two symbol intervals, such as e.g. a number n of symbol intervals equal to the number K of selected 703 data streams 130-1 , 130-2 in some embodiments.

Action 706

The value of the formed 705 binary label 420 is determined by collecting a number n of bits b1 , b2, bn from all of the data streams 130-1 , 130-2 according to the made mapping. Thus the number n of bits b1 , b2, ..., bn may be equal to a multiple of the number K of selected 703 data streams 130-1 , 130-2, i.e. n = mO K.

Action 707

A constellation point 410 is selected in the determined 704 modulation scheme 400, labelled according to the determined 706 binary label 420.

Action 708

Data representing the selected 707 constellation point 410 is transmitted in a time- frequency resource element.

According to some embodiments, a first data stream 130-1 and a second data stream 130- 2 may be selected 703. The determined 704 modulation scheme 400 may exhibit a plurality of distinct error protection levels for different bits b1 , b2, bn of said binary label 420, where each distinct error protection level may comprise an even number of bits b1 , b2, bn within the formed 705 binary label 420. Further, in every odd symbol interval, for each protection level: a first half of the bits b1 , b(n-1 ) may be mapped with the first data stream 130-1 and a second half of the bits b2, bn may be mapped with the second data stream 130-2 and in every even symbol interval, the first half of the bits b1 , b(n-1 ) may be mapped with the second data stream 130-2 and the second half of the bits b2, bn may be mapped with the first data stream 130-1 .

However, in some embodiments, data streams 130-1 , 130-2 out of a multitude Z≥ K of available data streams 130-1 , 130-2 may be selected 703. The binary label 420 may be formed 705 by collecting m₀ bits b1 , b2, b(m0) from each of said selected 703 K data streams 130-1 , 130-2. Thereafter, the binary label 420 of length m₀ bits b1 , b2, b(m₀K) may be formed. The determined 704 modulation scheme 400 may comprise a higher-order extended constellation of 2^m°^K symbols. Further, the binary label 420 may be formed 705 such that said data streams 130-1 , 130-2 have similar, or equal, error protec- tion level in some embodiments.

Figure 8 illustrates an embodiment of a transmitter 1 10 comprised in a wireless communication system 100. The transmitter 1 10 is configured for performing at least some of the previously described method actions 701-708, for multiplexing data streams 130-1 , 130-2 in a multiple access environment by providing dynamic stream-to-label mapping. The wireless communication network 100 may be based on 3rd Generation Partnership Project Long Term Evolution (3GPP LTE). The transmitter 1 10 may in some embodiments comprise e.g. a Transmission Point (TP), or a radio network node such as e.g. an evolved NodeB (eNodeB). Further, the wireless communication system 100 may be based on FDD or TDD in different embodiments. The recipient 120 may comprise a User Equipment (UE) in some embodiments wherein the transmission of data is made in the downlink.

However, the situation may in some embodiments be the opposite, such that the transmitter 1 10 comprises a UE and wherein the transmission of data is made in the uplink to be received by at least one recipient 120, which may comprise a TP or a radio network node such as e.g. an eNodeB.

Thus the transmitter 1 10 is configured for performing the method 700 according to at least some of the actions 701 -708. For enhanced clarity, any internal electronics or other com- ponents of the transmitter 1 10, not completely indispensable for understanding the herein described embodiments has been omitted from Figure 8.

The transmitter 1 10 comprises a transmitting circuit 830, configured for transmitting data on a plurality of data streams 130-1 , 130-2, to be received by at least one recipient 120 and also configured for transmitting data representing a constellation point 410 in a time- frequency resource elements.

In some embodiments, the transmitter 1 10 may comprise a receiving circuit 810, configured for obtaining a channel quality estimation such as e.g. a CQI e.g. from at least one recipient 120.

Such receiving circuit 810 in the transmitter 1 10 may be configured for receiving any wireless signals from the recipient 120 or any other arbitrary entity configured for wireless communication over a wireless interface according to some embodiments.

The received channel quality estimation from the at least one recipient 120 may be related to a channel, thereby indirectly directed to the data stream 130-1 , 130-2 in some embodiments. Additionally, the transmitter 1 10 also comprises a processor 820, configured for selecting a number of data streams 130-1 , 130-2 based on the obtained channel quality estimation. For example, data streams 130-1 , 130-2 associated with a received channel quality estima- tion exceeding a first threshold value, but not a second threshold value, where the second threshold value is higher than the first threshold value may be selected. Also, furthermore the processor 820 is also configured for determining a modulation scheme 400 to be utilised for the selected data streams 130-1 , 130-2, based on the received channel quality estimation related to the selected data streams 130-1 , 130-2. Furthermore the processor 820 is additionally configured for forming a binary label 420 capable of comprising n bits b1 , b2, b3, bn of all data streams 130-1 , 130-2, and mapping each bit position in such label 420 with a selected data stream 130-1 , 130-2. The processor 820 is also additionally configured for determining the value of the formed binary label 420 by collecting a number of n bits b1 , b2, bn from all the data streams 130-1 , 130-2 according to the mapping. Also, the processor 820 is furthermore in addition configured for selecting a constellation point 410 in the determined modulation scheme 400, labelled according to the determined binary label 420. The processor 820 may is further configured for performing the mapping dynamically, such that each bit b1 , b2, bn in the formed binary label 420 may be mapped a similar amount of times to each selected data stream 130-1 , 130-2 within a period comprising at least two symbol intervals. In some embodiments, the number of symbol intervals may be equal to the number Of selected data streams 130-1 , 130-2.

In some embodiments, the processor 820 may be further configured for performing the mapping cyclically, in order to achieve similar error protection level on the K selected data streams 130-1 , 130-2 over a period comprising at least two symbol intervals. In some embodiments, the number n of symbol intervals may be equal to the number K of selected data streams 130-1 , 130-2, such that n = K. In some such embodiments, the input index of the bits b1 , b2, bn may be permutated in each symbol interval in any arbitrary order, which then may be repeated.

The processor 820 may be further configured for selecting data streams 130-1 , 130-2 e.g. when the difference between the received respective channel quality estimation is smaller than a threshold value. Such threshold value may be predetermined or configurable in different embodiments.

The processor 820 may also be further configured for selecting a first data stream 130-1 and a second data stream 130-2. Also, the processor 820 may be configured for determining a modulation scheme 400, which exhibits a plurality of distinct error protection levels for different bits b1 , b2, bn of said binary label 420, where each distinct error protection level comprises an even number of bits b1 , b2, bn within the binary label 420, where, in every odd symbol interval, for each respective protection level: a first half of the bits b1 , b(n-1 ) may be mapped with the first data stream 130-1 and a second half of the bits b2, bn may be mapped with the second data stream 130-2 and in every even symbol interval, the first half of the bits b1 , b(n-1 ) may be mapped with the second data stream 130-2 and the second half of the bits b2, bn may be mapped with the first data stream 130-1 .

Such processor 820 may comprise one or more instances of a processing circuit, i.e. a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression "processor" may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones enumerated above. The processor 820 may in some embodiments be configured for selecting data streams 130-1 , 130-2 out of a multitude Z≥ K ot available data streams 130-1 , 130-2. Further, the processor 820 may be configured for forming the binary label 420 by collecting n = m₀K bits b1 , b2, b3, bn from said data streams 130-1 , 130-2 and forming the binary label 420 of length m₀ bits b1 , b2, bn. Furthermore, the processor 820 may be configured for determining a modulation scheme 400 which comprises a higher-order extended constellation of 2^m°^K symbols. In addition, the processor 820 may be configured for forming the binary label 420 such that said data streams 130-1 , 130-2 have similar or equal error protection level. In addition according to some embodiments, the transmitter 1 10 may in some embodiments also comprise at least one memory 825 in the transmitter 1 10. The optional memory 825 may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory 825 may comprise integrated circuits comprising silicon-based transistors. Further, the memory 825 may be volatile or non-volatile.

The actions 701-708 to be performed in the transmitter 1 10 may be implemented through the one or more processors 820 in the transmitter 1 10 together with a computer program comprising program code for performing the method 700 according to the described ac- tions 701-708, for multiplexing data streams 130-1 , 130-2 in a multiple access environment when the computer program is loaded into the processor 820 of the transmitter 1 10. The actions 701-708 to be performed in the transmitter 1 10 may further be implemented through the one or more processors 820 in the transmitter 1 10 together with a computer program product comprising a computer readable storage medium storing program code thereon for in a wireless communication system 100 for multiplexing data streams 130-1 , 130-2 in a multiple access environment, wherein the program code comprising instructions for executing the method 700 comprises transmitting 701 data on a plurality of data streams 130-1 , 130-2 to be received by at least one recipient 120; obtaining 702 a channel quality estimation; selecting 703 a number of K data streams 130-1 , 130-2, based on the obtained 702 channel quality estimation; determining 704 a modulation scheme 400 to be utilised for the K selected 703 data streams 130-1 , 130-2, based on the obtained 702 channel quality estimation; forming 705 a binary label 420 capable of containing bits b1 , b2, bn of all data streams 130-1 , 130-2, and mapping each bit position in such label 420 with a selected 703 data stream 130-1 , 130-2; determining 706 the value of the formed 705 binary label 420 by collecting a number of n bits b1 , b2, bn from each of the data streams 130-1 , 130-2 according to the mapping; selecting 707 a constellation point 410 in the determined 704 modulation scheme 400, labelled according to the determined 706 binary label 420; and transmitting 708 data representing the selected 707 constellation point 410 in at least one time-frequency resource element, according to some embodiments. The computer program product mentioned above may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the actions 701-708 according to some embodiments when being loaded into the processor 820. The data carrier may be, e.g., a hard disk, a CD ROM disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non transitory manner. The computer program product may furthermore be provided as computer program code on a server and downloaded to the transmitter 1 10, e.g., over an Internet or an intranet connection.

Figure 9 is a flow chart illustrating embodiments of a method 900 in a recipient 120 in a wireless communication system 100. The method 900 aims at receiving at least one multiplexing data stream 130-1 , 130-2 in a multiple access environment by providing feedback in form of estimated channel quality to the transmitter 1 10.

The wireless communication network 100 may be based on 3GPP LTE in some embodi- ments. The recipient 120 may comprise a UE in some embodiments, wherein reception is made in the downlink of data transmitted by the transmitter 1 10, which then may comprise a TP or a radio network node such as e.g. an eNodeB. Further, the wireless communication system 100 may be based on FDD or TDD in different embodiments.

However, the situation may in some embodiments be the opposite, such that the recipient 5 120 may comprise a TP or a radio network node such as e.g. an eNodeB and wherein the transmission of data is made in the uplink by the transmitter 1 10 which may comprise a UE.

To appropriately receive the at least one multiplexing data stream 130-1 , 130-2, the0 method 900 may comprise a number of actions 901 -906.

It is however to be noted that any, some or all of the described actions 901-906, may be performed in a somewhat different chronological order than the enumeration indicates, be performed simultaneously or even be performed in a completely reversed order according5 to different embodiments. Further, it is to be noted that some actions may be performed in a plurality of alternative manners according to different embodiments, and that some such alternative manners may be performed only within some, but not necessarily all embodiments. The method 900 may comprise the following actions: 0 Action 901

Data is received on at least one data stream 130-1 , 130-2, transmitted by a transmitter 1 10. The data may be received on a time-frequency resource element.

Action 902

5 This action may be performed within some, but not all embodiments.

A channel quality related to a channel associated with the received 901 data stream 130-1 , 130-2 may be estimated. The channel estimation may comprise a CQI in some embodiments of a channel associated with the received 901 data stream 130-1 , 130-2.

0

Action 903

This action may be performed within some, but not all embodiments.

The estimated 902 channel quality is transmitted, to be received by the transmitter 1 10.5 The channel quality may be associated with the received 901 data stream 130-1 , 130-2 and/ or the recipient 120, in order for the transmitter 1 10 to be able to detect which received channel quality estimation belongs to which data stream 130-1 , 130-2. Action 904

A modulation scheme 400 is determined to be utilised for the received 901 data stream 130-1 , 130-2, based on the estimated channel quality or on transmission parameter signal- ling information received from the transmitter 1 10.

Action 905

Data representing a constellation point 410 in a time-frequency resource element is received. The data may be received in form of time-frequency resource elements.

Action 906

The received 905 data is demapped by determining which bits b1 , b2, bn in a binary label 420, corresponding to the constellation point 410, that are associated with the received 901 data stream 130-1 , 130-2.

Figure 10 illustrates an embodiment of recipient 120 comprised in a wireless communication system 100. The recipient 120 is configured for performing at least some of the previously described method actions 901-906, for receiving at least one multiplexing data stream 130-1 , 130-2 in a multiple access environment by e.g. providing feedback in form of estimated channel quality to the transmitter 1 10, in some embodiments.

The wireless communication network 100 may be based on 3GPP LTE in some embodiments. The recipient 120 may comprise a UE in some embodiments, wherein reception is made in the downlink of data transmitted by the transmitter 1 10, which then may comprise a TP or a radio network node such as e.g. an eNodeB. Further, the wireless communication system 100 may be based on FDD or TDD in different embodiments.

However, the situation may in some embodiments be the opposite, such that the recipient 120 may comprise a TP or a radio network node such as e.g. an eNodeB and wherein the transmission of data is made in the uplink by the transmitter 1 10 which may comprise a UE.

Thus the recipient 120 is configured for performing the method 900 according to at least some of the actions 901 -906. For enhanced clarity, any internal electronics or other com- ponents of the recipient 120, not completely indispensable for understanding the herein described embodiments has been omitted from Figure 10. The recipient 120 comprises a receiving circuit 1010, configured for receiving data on at least one data stream 130-1 , 130-2, transmitted by a transmitter 1 10, and furthermore also configured for receiving data representing a constellation point 410 in a time-frequency resource element.

The recipient 120 also comprises a processor 1020, configured for determining a modulation scheme 400 to be utilised for the received data stream 130-1 , 130-2. Additionally, the processor 1020 is also configured for demapping the received data by determining which bits b1 , b2, bn in a binary label 420, corresponding to the constellation point 410, which have been associated with the data stream 130-1 , 130-2.

In some embodiments, the processor is configured for estimating a channel quality related to a channel associated with the received data stream 130-1 , 130-2. Such processor 1020 may comprise one or more instances of a processing circuit, i.e., a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression "processor" may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones enumerated above.

Further, the recipient 120 also comprises a transmitting circuit 1030, configured for transmitting the estimated channel quality, to be received by the transmitter 1 10. In some alternative embodiments, the recipient 120 and/ or the processor 1020 may comprise an estimating unit, configured for estimating a channel quality related to a channel associated with the received data stream 130-1 , 130-2. Further, the recipient 120 and/ or the processor 1020 may also comprise a determining unit, configured for determining a modulation scheme 400 to be utilised for the received data stream 130-1 , 130-2, based on the estimated channel quality or on transmission parameter signalling information received from the transmitter 1 10. In addition, the recipient 120 and/ or the processor 1020 may further comprise a demapping unit, configured for demapping the received data by determining which bits b1 , b2, bn in a binary label 420, corresponding to the constellation point 410 that are associated with the data stream 130-1 , 130-2.

In addition, the recipient 120 in some embodiments also may comprise at least one memory 1025 in the recipient 120. The optional memory 1025 may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory 1025 may comprise integrated circuits comprising silicon-based transistors. Further, the memory 1025 may be volatile or non-volatile.

5

The actions 901-906 to be performed in the recipient 120 may be implemented through the one or more processors 1020 in the recipient 120 together with computer program product for performing the functions of the actions 901 -906.

10 Thus a computer program comprising program code for performing the method 900 according to any of actions 901-906, for receiving at least one multiplexing data stream 130- 1 , 130-2 in a multiple access environment when the computer program is loaded into the processor 1020 of the recipient 120.

15 The computer program product may comprise a computer readable storage medium storing program code thereon for receiving at least one multiplexing data stream 130-1 , 130-2 in a multiple access environment in a wireless communication system 100, wherein the program code comprising instructions for executing a method 900 comprises determining 904 a modulation scheme 400 to be utilised for the received data stream 130-1 , 130-2,

20 based on estimated channel quality or on transmission parameter signalling information received from the transmitter 1 10; receiving 905 data representing a constellation point 410 in a time-frequency resource element; demapping 906 the received 905 data by determining which bits b1 , b2, bn in a binary label 420, corresponding to the constellation point 410, that are associated with the data stream 130-1 , 130-2 according to some embodi-

25 ments.

The computer program product mentioned above may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the actions 901 -906 according to some embodiments when being loaded into the processor

30 1020. The data carrier may be, e.g., a hard disk, a CD ROM disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non transitory manner. The computer program product may furthermore be provided as computer program code on a server and downloaded to the recipient 120, e.g., over an Internet or an intranet connec-

35 tion. The terminology used in the description of the embodiments as illustrated in the accompanying drawings is not intended to be limiting of the described methods 700, 900; transmitter 1 10 and/ or recipient 120. Various changes, substitutions and/ or alterations may be made, without departing from the invention as defined by the appended claims.

As used herein, the term "and/ or" comprises any and all combinations of one or more of the associated listed items. In addition, the singular forms "a", "an" and "the" are to be interpreted as "at least one", thus also possibly comprising a plurality of entities of the same kind, unless expressly stated otherwise. It will be further understood that the terms "in- eludes", "comprises", "including" and/ or "comprising", specifies the presence of stated features, actions, integers, steps, operations, elements, and/ or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, components, and/ or groups thereof. A single unit such as e.g. a processor may fulfil the functions of several items recited in the claims. The mere fact that cer- tain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/ distributed on a suitable medium, such as an optical storage medium or a solid- state medium supplied together with or as part of other hardware, but may also be distributed in other forms such as via Internet or other wired or wireless communication system.

Claims

1 . A method (700) in a transmitter (1 10) in a wireless communication network (100), for multiplexing data streams (130-1 , 130-2) in a multiple access environment, the method (700) comprising:

transmitting (701 ) data on a plurality of data streams (130-1 , 130-2), to be received by at least one recipient (120);

obtaining (702) a channel quality estimation;

selecting (703) a number Of data streams (130-1 , 130-2), based on the obtained

(702) channel quality estimation;

determining (704) a modulation scheme (400) to be utilised for the selected (703) data streams (130-1 , 130-2), based on the obtained (702) channel quality estimation; forming (705) a binary label (420) capable of containing bits (b1 , b2, bn) of all

K data streams (130-1 , 130-2), and mapping each bit position in such label (420) with a selected (703) data stream (130-1 , 130-2);

determining (706) the value of the formed (705) binary label (420) by collecting a number n of bits (b1 , b2, bn) from all of the data streams (130-1 , 130-2) according to the mapping;

selecting (707) a constellation point (410) in the determined (704) modulation scheme (400), labelled according to the determined (706) binary label (420); and

transmitting (708) data representing the selected (707) constellation point (410) in a time-frequency resource element.

2. The method (700) according to claim 1 , wherein the mapping is made dynamically, such that each bit (b1 , b2, bn) in the formed (705) binary label (420) is mapped a simi- lar amount of times to each selected (703) data stream (130-1 , 130-2) within a period comprising at least two symbol intervals.

3. The method (700) according to any of claim 1 or claim 2, wherein the mapping is made cyclically in order to achieve similar error protection level on all the selected (703) streams (130-1 , 130-2) over a period comprising at least two symbol intervals.

4. The method (700) according to any of claims 1-3, wherein the obtained (702) channel quality estimation is related to a channel, indirectly directed to a data stream (130- 1 , 130-2); and wherein data streams (130-1 , 130-2) are selected (703) when the difference between the obtained (702) respective channel quality estimation is smaller than a threshold value.

5. The method (700) according to any of claims 1-4, wherein a first data stream (130- 1 ) and a second data stream (130-2) are selected (703) and wherein the determined (704) modulation scheme (400) exhibits a plurality of distinct error protection levels for different bits (b1 , b2, bn) of said binary label (420), where each distinct error protection level comprises an even number of bits (b1 , b2, bn) within the formed (705) binary label (420), where, in every odd symbol interval, for each protection level: a first half of the bits (b1 , b(n-1 )) is mapped with the first data stream (130-1 ) and a second half of the bits (b2, bn) is mapped with the second data stream (130-2) and in every even symbol interval, the first half of the bits (b1 , b(n-1 )) is mapped with the second data stream (130- 2) and the second half of the bits (b2, bn) is mapped with the first data stream (130-1 ).

6. The method (700) according to any of claims 1-5, wherein data streams (130-1 , 130-2) out of a multitude Z≥ of available data streams (130-1 , 130-2) are selected (703); and wherein the binary label (420) is formed (705) by collecting m₀ bits (b1 , b2, bm₀) from each of said selected (703) data streams (130-1 , 130-2) and forming (705) the binary label (420) of length m₀ bits (b1 , b2, bm₀); and wherein the determined (704) modulation scheme (400) comprises a higher-order extended constellation of 2^m°^K symbols; and wherein the binary label (420) is formed (705) such that said K data streams (130-1 , 130-2) have similar error protection level.

7. The method (700) according to any of claims 1 -6, wherein the transmitter (1 10) comprises a Transmission Point, TP, and wherein the transmission (701 , 708) of data is made in the downlink to be received by at least one recipient (120), comprising a User Equipment, UE.

8. The method (700) according to any of claims 1 -5, wherein the transmitter (1 10) comprises a User Equipment, UE, and wherein the transmission (701 , 708) of data is made in the uplink from the same transmission circuit (830), to be received by at least one recipient (120) comprising a Transmission Point, TP.

9. The method (700) according to any of claims 1-8, wherein the transmitter (1 10) is operating in Time Division Duplex, TDD, mode and the action of obtaining (702) the channel quality estimation comprises receiving a signal from the recipient (120) on the reverse link and estimating the channel quality of the received signal.

10. The method (700) according to any of claims 1-9, wherein the transmitter (1 10) is operating in Frequency Division Duplex, FDD, mode or in TDD mode and the action of ob- taining (702) the channel quality estimation comprises receiving the channel quality estimation from the recipient (120).

1 1. A transmitter (1 10) in a wireless communication network (100), configured for mul- 5 tiplexing data streams (130-1 , 130-2) in a multiple access environment, the transmitter (1 10) comprising:

a transmitting circuit (830), configured for transmitting data on a plurality of data streams (130-1 , 130-2), to be received by at least one recipient (120) and also configured for transmitting data representing a constellation point (410) in a time-frequency resource 10 element;

a receiving circuit (810), configured for obtaining a channel quality estimation; and a processor (820), configured for selecting a number K of data streams (130-1 , 130-2) based on the obtained channel quality estimation; and also configured for determining a modulation scheme (400) to be utilised for the selected data streams (130-1 , 130-2),

15 based on the obtained channel quality estimation related to the K selected data streams (130-1 , 130-2); and furthermore configured for forming a binary label (420) capable of comprising bits (b1 , b2, bn) of all data streams (130-1 , 130-2), and mapping each bit position in such label (420) with a selected data stream (130-1 , 130-2); and additionally configured for determining the value of the formed binary label (420) by collecting a num-

20 ber n of bits (b1 , b2, bn) from all of the data streams (130-1 , 130-2) according to the mapping; and furthermore also in addition configured for selecting a constellation point (410) in the determined modulation scheme (400), labelled according to the determined binary label (420).

25 12. The transmitter (1 10) according to claim 1 1 , wherein the processor (820) is further configured for performing the mapping dynamically, such that each bit (b1 , b2, bn) in the formed binary label (420) is mapped a similar amount of times to each selected data stream (130-1 , 130-2) within a period comprising at least two symbol intervals.

30 13. The transmitter (1 10) according to any of claim 1 1 or claim 12, wherein the processor (820) is further configured for performing the mapping cyclically, in order to achieve similar error protection level on the K selected streams (130-1 , 130-2) over a period comprising at least two symbol intervals.

35 14. The transmitter (1 10) according to any of claims 1 1-13, wherein the obtained channel quality estimation is related to a channel, indirectly directed to a data stream (130- 1 , 130-2) and wherein the processor (820) is further configured for selecting K data streams (130-1 , 130-2) when the difference between the received respective channel quality estimation is smaller than a threshold value.

15. The transmitter (1 10) according to any of claims 1 1 -14, wherein the processor (820) is further configured for selecting a first data stream (130-1 ) and a second data stream (130-2), and wherein the processor (820) also is configured for determining a modulation scheme (400), which exhibits a plurality of distinct error protection levels for different bits (b1 , b2, bn) of said binary label (420), where each distinct error protection level comprises an even number of bits (b1 , b2, bn) within the binary label (420), where, in every odd symbol interval, for each respective protection level: a first half of the bits (b1 , b(n-1 )) is mapped with the first data stream (130-1 ) and a second half of the bits (b2, bn) is mapped with the second data stream (130-2) and in every even symbol interval, the first half of the bits (b1 , b(n-1 )) is mapped with the second data stream (130-2) and the second half of the bits (b2, bn) is mapped with the first data stream (130-1 ).

16. The transmitter (1 10) according to any of claims 1 1-15, wherein the processor (820) is further configured for selecting data streams (130-1 , 130-2) out of a multitude Z ≥ K of available data streams (130-1 , 130-2); and wherein the processor (820) also is configured for forming the binary label (420) by collecting m₀ bits (b1 , b2, bm₀) from each of said data streams (130-1 , 130-2) and forming the binary label (420) of length m₀ K bits (b1 , b2, bm₀); and wherein the processor (820) is configured for determining a modulation scheme (400) which comprises a higher-order extended constellation of 2^m°^K symbols and wherein the processor (820) is further configured for forming the binary label (420) such that said data streams (130-1 , 130-2) have similar error protection level.

17. The transmitter (1 10) according to any of claims 1 1 -16, wherein the transmitter (1 10) comprises a Transmission Point, TP, and wherein the transmission of data is made in the downlink to be received by at least one recipient (120), which comprises a User Equipment, UE.

18. The transmitter (1 10) according to any of claims 1 1 -17, wherein the transmitter (1 10) comprises a User Equipment, UE, and wherein the transmission of data is made in the uplink to be received by at least one recipient (120), which comprises a Transmission Point, TP.

19. The transmitter (1 10) according to any of claims 1 1 -18, wherein the transmitter (1 10) is operating in TDD mode and configured for receiving a signal from the recipient (120) on the reverse link and estimating the channel quality of the received signal.

20. The transmitter (1 10) according to any of claims 1 1 -19, wherein the transmitter (1 10) is operating either in FDD mode or in TDD mode and configured for receiving the channel quality estimation from the recipient (120).

21. A computer program comprising program code for performing a method (700) ac- cording to any of claims 1-10, for multiplexing data streams (130-1 , 130-2) in a multiple access environment when the computer program is loaded into a processor (820) of the transmitter (1 10) according to any of claims 1 1 -19.

22. A computer program product comprising a computer readable storage medium storing program code thereon for in a wireless communication system (100) for multiplexing data streams (130-1 , 130-2) in a multiple access environment, wherein the program code comprising instructions for executing a method (700) comprising:

transmitting (701 ) data on a plurality of data streams (130-1 , 130-2), to be received by at least one recipient (120);

obtaining (702) a channel quality estimation;

selecting (703) a number Of data streams (130-1 , 130-2), based on the obtained (702) channel quality estimation;

determining (704) a modulation scheme (400) to be utilised for the selected (703) data streams (130-1 , 130-2), based on the obtained (702) channel quality estimation; forming (705) a binary label (420) capable of containing bits (b1 , b2, bn) of all

K data streams (130-1 , 130-2), and mapping each bit position in such label (420) with a selected (703) data stream (130-1 , 130-2);

determining (706) the value of the formed (705) binary label (420) by collecting a number n of bits (b1 , b2, b3, bn) from all of the data streams (130-1 , 130-2) according to the mapping;

selecting (707) a constellation point (410) in the determined (704) modulation scheme (400), labelled according to the determined (706) binary label (420); and

transmitting (708) data representing the selected (707) constellation point (410) in a time-frequency resource element.

23. A method (900) in a recipient (120) in a wireless communication network (100), for receiving at least one multiplexing data stream (130-1 , 130-2) in a multiple access environment, the method (900) comprising:

receiving (901 ) data on at least one data stream (130-1 , 130-2), transmitted by a 5 transmitter (1 10);

determining (904) a modulation scheme (400) to be utilised for the received (901 ) data stream (130-1 , 130-2), based on an estimated channel quality or on transmission parameter signalling information received from the transmitter (1 10);

receiving (905) data representing a constellation point (410) in a time-frequency 10 resource element;

demapping (906) the received (905) data by determining which bits (b1 , b2, bn) in a binary label (420), corresponding to the constellation point (410), that are associated with the data stream (130-1 , 130-2).

15 24. The method (900) according to claim 23, wherein the recipient (120) is operating in TDD mode.

25. The method (900) according to any of claim 23 or claim 24, wherein the recipient (120) is operating either in FDD mode or in TDD mode and wherein the method (900) fur-

20 ther comprises:

estimating (902) a channel quality related to a channel associated with the received (901 ) data stream (130-1 , 130-2);

transmitting (903) the estimated (902) channel quality, to be received by the transmitter (1 10).

25

26. The method (900) according to any of claims 23-25, wherein the recipient (120) comprises a UE; the reception (901 ) is made in the downlink of data transmitted by the transmitter (1 10), which comprises a TP.

30 27. The method (900) according to any of claims 23-25, wherein the recipient (120) comprises a TP; the reception (901 ) is made in the uplink of data transmitted by the transmitter (1 10), which comprises a UE.

28. A recipient (120) in a wireless communication network (100), configured for receiv- 35 ing at least one multiplexing data stream (130-1 , 130-2) in a multiple access environment, the recipient (120) comprising: a receiving circuit (1010), configured for receiving data representing a constellation point (410) in a time-frequency resource element; and wherein the receiving circuit (1010) is furthermore also configured for receiving data on at least one data stream (130-1 , 130-2), transmitted by a transmitter (1 10);

5 a processor (1020), configured for determining a modulation scheme (400) to be utilised for the received data stream (130-1 , 130-2) and additionally configured for demap- ping the received data by determining which bits (b1 , b2, bn) in a binary label (420), corresponding to the constellation point (410), which have been associated with the data stream (130-1 , 130-2).

10

29. The recipient (120) according to claim 28, wherein the recipient (120) is configured for operation in TDD mode.

30. The recipient (120) according to any of claim 28 or claim 29, wherein the recipient 15 (120) is configured for operation in either FDD mode or in TDD mode, and wherein the processor (1020) is further configured for estimating a channel quality related to a channel associated with the received data stream (130-1 , 130-2); and wherein the recipient (120) further comprises a transmitting circuit (1030), configured for transmitting the estimated channel quality, to be received by the transmitter (1 10).

20

31. The recipient (120) according to any of claims 28-30, wherein the recipient (120) comprises a UE; the reception is made in the downlink of data transmitted by the transmitter (1 10), which comprises a TP.

25 32. The recipient (120) according to any of claims 28-30, wherein the recipient (120) comprises a TP; the reception is made in the uplink of data transmitted by the transmitter (1 10), which comprises a UE.

33. A computer program comprising program code for performing a method (900) ac- 30 cording to any of claims 23-27, for receiving at least one multiplexing data stream (130-1 ,

130-2) in a multiple access environment when the computer program is loaded into a processor (1020) of a recipient (120) according to any of claims 28-32.

34. A computer program product comprising a computer readable storage medium 35 storing program code thereon for receiving at least one multiplexing data stream (130-1 ,

130-2) in a multiple access environment in a wireless communication system (100), wherein the program code comprising instructions for executing a method (900) comprising:

receiving (901 ) data on at least one data stream (130-1 , 130-2), transmitted by a transmitter (1 10);

determining (904) a modulation scheme (400) to be utilised for the received (901 ) data stream (130-1 , 130-2), based on an estimated channel quality or on transmission parameter signalling information received from the transmitter (1 10);

receiving (905) data representing a constellation point (410) in a time-frequency resource element;

demapping (906) the received (905) data by determining which bits (b1 , b2, bn) in a binary label (420), corresponding to the constellation point (410), that are associated with the data stream (130-1 , 130-2).