WO2015019185A2

WO2015019185A2 - Conveying scheduling information for aiding interference cancellation in a wireless communication system

Info

Publication number: WO2015019185A2
Application number: PCT/IB2014/002188
Authority: WO
Inventors: Sairamesh Nammi
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2013-08-09
Filing date: 2014-08-11
Publication date: 2015-02-12
Also published as: WO2015019185A3

Abstract

Methods, devices, and computer program products for conveying scheduling information for aiding interference cancellation in a code multiplexed wireless communication system are provided. The method for aiding interference cancellation in a first mobile device is performed by a first node, that causes the interference to the first mobile device communicating with a second node, by communicating with a plurality of mobile devices in a cell in a heterogeneous communication network. The method includes determining whether to use code multiplexing for communicating with the plurality of mobile devices. When code multiplexing is used, then the method further includes computing a geometry for each mobile device of the plurality of mobile devices scheduled for communication with the first node, determining a scheduled mobile device, out of the plurality of mobile devices, having the lowest geometry, and transmitting a first message to the first mobile device, wherein the first message includes scheduling information for the scheduled mobile device determined to have the lowest geometry.

Description

Conveying Scheduling Information for Aiding Interference Cancellation in a

Wireless Communication System

TECHNICAL FIELD

[0001] This disclosure relates generally to heterogeneous communication networks and, more particularly, to methods, devices, and computer program products for conveying scheduling information for aiding interference cancellation in a code multiplexed wireless communication system.

BACKGROUND

[0002] Mobile communication devices such as terminals are also known as, e.g., User Equipments (UEs), mobile terminals, wireless terminals and/or mobile stations. Terminals are enabled to communicate wirelessly in a cellular communications network or wireless communication system, sometimes also referred to as a cellular radio system or cellular network. The communication may be performed, e.g., between two terminals, between a terminal and a regular telephone and/or between a terminal and a server via a Radio Access Network (RAN) and possibly one or more core networks, comprised within the cellular communications network.

[0003] Terminals may further be referred to as mobile telephones, cellular telephones, laptops, or surf plates with wireless communication capability, just to mention some further examples. The terminals 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 RAN, with another entity, such as another terminal or a server.

[0004] The cellular communications network covers a geographical area which is divided into cell areas, wherein each cell area being served by an access node such as a base station, e.g., a Radio Base Station (RBS), which sometimes may be referred to as, e.g., "eNB", "eNodeB", "NodeB", "B node", or Base Transceiver Station (BTS), depending on the technology and terminology used. The base stations may be of different classes such as, e.g., macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. Such nodes may also be referred to as either a macro node or a low power node (LPN), e g depending on transmission power and/or cell size.

[0005] A cell is the geographical area where radio coverage is provided by the base station at a base station site. One base station, situated on the base station site, may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the terminals within range of the base stations. In the context of this disclosure, the expression Downlink (DL) is used for the transmission path from the base station to the mobile station. The expression Uplink (UL) is used for the transmission path in the opposite direction, i.e., from the mobile station to the base station.

[0006] In the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), base stations, which may be referred to as eNodeBs or even eNBs, may be directly connected to one or more core networks. The 3GPP LTE radio access standard has been written in order to support high bitrates and low latency both for uplink and downlink traffic. All data transmission in LTE is controlled by the radio base station. [0007] During the last few years, cellular operators have started to offer mobile broadband based on WCDMA HSPA. Further, fuelled by new devices designed for data applications, the end user performance requirements are steadily increasing. The large uptake of mobile broadband has resulted in heavy traffic volumes that need to be handled by the HSPA networks. Therefore, techniques that allow cellular operators to manage their spectrum resources more efficiently are of large importance.

[0008] Few such techniques whereby it is possible to improve the downlink performance would be to introduce support for 4-branch MIMO, multiflow

communication, multi carrier deployment etc. Since improvements in spectral efficiency per link are approaching theoretical limits, the next generation technology is about improving the spectral efficiency per unit area. In other words, the additional features for HSDPA need to provide a uniform user experience to users anywhere inside a cell by changing the topology of traditional networks. Currently, 3GPP has been working on this aspect of using Heterogeneous networks. See, e.g., RP-121436, Proposed SID: Study on UMTS Heterogeneous Networks, TSG RAN Meeting #57, Chicago, USA , 4th -7th September 2012.

[0009] Homogeneous Networks: A homogeneous network is a network of base stations {e.g., Node B) in a planned layout and a collection of user terminals in which all base stations have similar transmit power levels, antenna patterns, receiver noise floors, and similar backhaul connectivity to the data network. Moreover, all base stations offer unrestricted access to user terminals in the network, and serve roughly the same number of user terminals. Current wireless systems that come under this category are, for example, GSM, WCDMA, HSDPA, LTE, Wimax, etc. [00010] Heterogeneous Networks: In a heterogeneous network 100, in addition to the planned or regular placement of macro base stations 102, several pico/femto/relay base stations (i.e., LPNs) 104 are deployed, as shown in Figure 1 . Note that the power transmitted by these pico/femto/relay base stations 104 is relatively small compared to that of macro base stations 102, which can be up to 40 W as compared to that of 2 W for pico/femto/relay base stations. These Low Power Nodes (LPNs) 104 are deployed to eliminate coverage holes in the homogeneous networks (using macro only). Hence, the capacity in hot-spots is thereby improved. Due to their lower transmit power and smaller physical size, pico/femto/relay base stations can offer flexible site acquisitions. [00011] The Low power nodes (LPNs) in a heterogeneous network can have a. a different cell identifier as that of macro cell (different cells) or

b. the same cell identifier as that of macro cell (soft, shared, or combined cell).

[00012] Figure 2 shows the heterogeneous network 200 where low power nodes (LPNs) 104 create different cells 202 and 204. Simulations show that using low power nodes (LPNs) in a macro cell offers load balancing, thereby increasing gains in system throughout as well as cell edge user throughput.

[00013] One disadvantage of the above method is that each cell LPN creates a different cell, hence a UE needs to do soft handover when moving from one LPN to macro or to another LPN. Hence, higher layer signaling is needed to perform handover. [00014] Figure 3 shows the heterogeneous network 300 where low power nodes 104 are part of the macro cell 302. This is sometimes referred to as a soft cell or shared cell. This set up avoids the frequent soft handovers, hence avoiding higher layer signaling. Note that in this deployment 400 all the nodes 402 are coupled to the central node (in this case Macro Node) 404 via high speed data link 406, as shown in Figure 4.

[00015] Figure 4 shows the typical configuration of a combined cell deployment 400, where the central controller 402 in the combined cell takes responsibility for collecting operational statistics information of network environment measurements. The decision of which nodes should transmit to a specific UE is made by the central controller based on the information provided by the UE or by the central controller on its own. The cooperation among various nodes is instructed by the central controller and implemented in a centralized way.

[00016] Note that even though huge gains in terms of average sector throughput are achieved with the introduction of LPNs, the interference structure becomes more complex in Heterogeneous networks. For example, when a UE is served by a LPN, individual UE link throughout is impacted due to the interference of Macro Node power.

[00017] Figure 5 shows the link performance when the UE which is scheduled by a LPN experiences a strong interference from the macro node which is serving a different UE. Note that the interference due to other nodes is modeled as white noise.

[00018] It can be observed from Figure 5 that there is huge performance degradation with the macro interference. The performance loss is in range of 100% at high geometries.

[00019] What is needed are ways to cancel or reduce such interference.

SUMMARY [00020] It is therefore an object of this disclosure to improve the possibilities for network assisted interference mitigation a mobile devices suffering from interference in wireless communication networks.

[00021] According to some embodiments, methods, devices, and computer program products have been developed that provide for conveying scheduling information for aiding interference cancellation in a code multiplexed wireless

communication system.

[00022] In one aspect, a method, performed by a first node for aiding cancellation of interference in a first mobile device communicating with a second node, where the interference is caused by the first node communicating with a plurality of mobile devices and operating in a cell in a heterogeneous communication network, includes

determining, in the first node, whether to use code multiplexing for communicating with the plurality of mobile devices. When code multiplexing is used,the method includes (1 ) computing, in the first node, a geometry for each mobile device out of the plurality of mobile devices scheduled for communication with the first node, (2) determining, in the first node, a scheduled mobile device, out of the plurality of mobile devices having the lowest geometry, and (3)transmitting, from the first node, a first message to the first mobile device, wherein the first message includes scheduling information for the scheduled mobile device determined to have the lowest geometry.

[00023] In some embodiments, the first node is a macro node and the second node is a low power node.

[00024] In some embodiments, the mobile devices are user equipments (UEs) and the scheduling information includes at least one of (i) UE Identities (IDs) for the UEs scheduled for communication with the first node, (ii) modulation information, (iii) a transport block size, and (iv).

[00025] In some embodiments, the geometry for each mobile device of the plurality of mobile devices scheduled for communication is computed based on one or more of downlink (DL) scheduling, channel quality information (CQI) reporting by each mobile device of the plurality of mobile devices scheduled for communication with the second node, and uplink measurements.

[00026] In some embodiments, the second message is a high speed shared control channel (HS-SCCH) order.

[00027] In some embodiments, a first node aids cancellation of interference in a first mobile device communicating with a second node, where the first node is configured to communicate with a plurality of mobile devices and being operable in a cell in a heterogeneous communication network. The first node includes a processor, a memory coupled to the processor, a network interface coupled to the processor, a transceiver coupled to the network interface, and an antenna coupled to the transceiver configured to transmit and receive messages. The processor is configured to determine whether to use code multiplexing for communicating with the plurality of mobile devices.When code multiplexing is used, the processor is configured to (1 ) compute a geometry for each mobile device out of the plurality of mobile devices scheduled for communication with the first node, (2) determine a scheduled mobile device, out of the plurality of mobile devices, having the lowest geometry, and (3)transmit a first message to the first mobile device, wherein the first message includes scheduling information for the scheduled mobile device determined to have the lowest geometry. [00028] In the methods, devices, and computer program products described herein, scheduling information is conveyed with minimum power consumption, which can aid the other cell UE in canceling the interference while, at the same time, not deteriorating its own cell performance. The methods, devices, and computer program products described herein are applicable for both co-channel and combined cell deployments.

BRIEF DESCRIPTION OF THE DRAWINGS

[00029] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present disclosure and, together with the description, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the embodiments disclosed herein. In the drawings, like reference numbers indicate identical or functionally similar elements.

[00030] FIG. 1 is a schematic diagram illustrating a wireless communication system with a heterogeneous network deployment showing low power nodes (LPNs) deployed in a macro cell area of a macro base station.

[00031] FIG. 2 is a schematic diagram illustrating a wireless communication system with a heterogeneous network deployment showing low power nodes (LPNs) in a co-channel heterogeneous network.

[00032] FIG. 3 is a schematic diagram illustrating a wireless communication system with a heterogeneous network deployment showing low power nodes (LPNs) as part of the macro cell. [00033] FIG. 4 is a schematic diagram illustrating a wireless communication system with a combined cell network deployment.

[00034] FIG. 5 is a graph illustrating simulated link level throughput in a cell range expansion area where the user equipment (UE) performance is impacted due to dominant macro base station interference.

[00035] FIG. 6 is a graph illustrating simulated link throughput using network assistance.

[00036] FIG. 7 is a block diagram of an interference cancellation receiver.

[00037] FIG. 8 is a message sequence diagram showing messages exchanged between a node and a victim user equipment (UE) during a data call setup.

[00038] FIG. 9 is a schematic diagram illustrating a wireless communication system with a heterogeneous network deployment showing interference caused by a macro node on the user equipment (UE) connected to the low power node (LPN).

[00039] FIG. 10 is a schematic diagram illustrating a wireless communication system with a heterogeneous network deployment showing a simulation scenario using network assistance.

[00040] FIG. 1 1 is a flow chart illustrating a process in accordance with exemplary embodiments.

[00041] FIG. 12 is a flow chart illustrating a process in accordance with exemplary embodiments.

[00042] FIG. 13 is a flow chart illustrating a process in accordance with exemplary embodiments. [00043] FIG. 14 is a block diagram of an access node in accordance with exemplary embodiments.

[00044] FIG. 15 is a block diagram of a wireless device in accordance with exemplary embodiments.

[00045] FIG. 16 is a block diagram of a control node in accordance with exemplary embodiments.

DETAILED DESCRIPTION

[00046] Network Assisted Interference Cancellation

[00047] To enable network assisted interference mitigation at a victim UE, the network (can be macro, LPN, or both) may send assistance information about the users which are scheduled during specific TTIs in interfering cells, i.e., causing interference to the victim UE.

[00048] Figure 6 shows the link performance when the network signals the scheduling information of the interferes Figure 6 shows that significant performance gains can be achieved if the UE knows the information about the interfering signals. In the simulation, the interference signal was re-constructed at the UE receiver and the interference is removed from after the detector output.

[00049] Figure 6 also shows that, with network {e.g., Macro, LPN, or both) assistance, the interference can almost be mitigated with a serial interference

cancelation receiver. Such a receiver is commonly referred to as an advanced receiver, enhanced receiver, interference mitigation receiver, interference cancellation receiver etc. For example, the network can signal the scheduling information of the interfering link using HS-SCCH orders, etc. Dedicated HS-SCCH orders which convey information about either the scheduling information or the UE id (e.g., H-RNTI) of the UE which is scheduled are sent.

[00050] In HSDPA, a macro or low power node (LPN) can schedule multiple UEs in a single TTI using code multiplexing, i.e., 15 data codes are shared between multiple UEs. In these cases, the Node B (either macro or LPN) sends multiple HS-SCCH orders for conveying the scheduling information. Note that each HS-SCCH order consumes a certain amount of power. For example, -10 dB power is allocated for each HS-SCCH order. Hence, with multiple HS-SCCH orders, the power allocated for signaling increases. Since the total power in any node is constant, the power allocated for data transmission in its own cell decreases. This implies that its own cell throughput is reduced.

[00051] The power allocated for signaling can be reduced by sending a common HS-SCCH order for conveying scheduling parameters for aiding interference

cancellation at a UE. Exemplary wireless communication methods, networks, nodes, and devices providing for a network in which a common-HS-SCCH order for HSDPA can be sent to a group of UEs in the network are described in WO2013/176606.

[00052] Exemplary wireless communication methods, networks, nodes, and devices providing for conveying scheduling information using a common HS-SCCH order with network assistance include, but are not limited to group of UES it can be sent to a dedicated UE. A common HS-SCCH order for conveying the scheduling

parameters for aiding the interference cancellation at a UE are sent.

[00053] FIG. 7 is a block diagram of an interference cancellation receiver 700, which will be benefitted by network assistance. The interference cancellation receiver 700 may include a decision box 702 , which is used to decide whether interference cancellation is needed or not needed. The victim UE (e.g., UE experiencing

interference) may determine how to use the network assisted information. The exemplary methods, devices, and computer program products described herein do not limit the UE's interference capability.

[00054] An example of interference cancellation, according to some embodiments, is disclosed. Assume that there are Np interfering nodes (macro or LPN) deployed. The received signal during a slot can be written as follows:

Where Ho the channel between the connected node and the UE , H, is the channel between the j^th node and the UE. Note that the channel is represented by a Toeplitz matrix. The vector xp denotes the common pilot chip sequence, xco denotes the control channel chip sequence from the macro node, and x^o denotes the data chip sequence from the macro node. The pilot symbols, control channel symbols and the data symbols are different from each node. Hence ¾^■ denotes the pilot channel chip sequence from node j, xcj denotes the control channel chip sequence from node j, and ¾ denotes the data chip sequence from node j. The variables P_Po , Pco , and Pdo , respectively, are the transmitted power levels for the common pilot, control channels (overhead channels), data channel (HS-PDSCH) from the desired node, and P_Pj , P_cj , and i¾ , respectively, are the transmitted power levels for the common pilot, control channels (overhead channels), and data channel (HS-PDSCH) from the j^th node. [00055] The variable Lo is the path gain from the desired node to the UE and Lj is the path gain from the j^th node to the UE, and n is the additive white Gaussian noise which includes both the thermal noise and other-cell interference.

[00056] It can be observed that the desired signal's pilot, control channel and data channel are impacted by the interference. At least three types of interferences cancellation are possible.

a. Pilot cancellation;

b. Control channel (overhead channel) cancellation; and

c. Data traffic channel cancellation.

[00057] Common HS-SCCH orders for Aiding Inference Cancellation

[00058] The use of common HS-SCCH orders for conveying scheduling information to all UEs allowing a single HS-SCCH order to address multiple UEs provides means for sending control commands to many UEs without sending as many HS-SCCH orders.

[00059] A new type of common H-RNTI is defined to be used together with HS- SCCH orders. By using the same H-RNTI for many UEs, a common HS-SCCH order can be defined. In some embodiments, this new UE H-RNTI is provided to a group of UEs.

[00060] The HS-SCCH order is scrambled with the cell-specific downlink scrambling code in the same way as in existing 3GPP specifications and understood by one of ordinary skill in the art. This means that HS-SCCH orders from a particular cell will only affect UEs that are monitoring HS-SCCH channels (i.e., HS-SCCH

channelization codes) in that cell. In existing 3GPP specifications, the UEs monitor a number of HS-SCCH channels in the serving HS-DSCH cell and in any activated secondary serving HS-DSCH cells and up to one HS-SCCH channel in a non-serving cell (for triggering of enhanced serving cell change).

[00061] In case of UE-specific HS-SCCH orders, the order is acknowledged by the UE with an ACK codeword in the HARQ-ACK field on the HS-DPCCH channel. The UE never sends a NACK in response to an HS-SCCH order. If the UE does not

acknowledge (ACK) the order, the NodeB can choose to retransmit the order, possibly with a higher transmit power, until an ACK is received from the UE (or until a maximum number of retransmissions has been reached).

[00062] In the case of common HS-SCCH orders for interference cancellation, the UE may not need to send an ACK/NAK. This is because the information needs to be sent dynamically since there is a delay involved with sending ACK/NAK before the order is applied.

[00063] Common HS-SCCH orders will work without any ACK/NAK feedback from UE. The Common HS-SCCH order may contain scheduling information or a UE ID. If scheduling information is sent, the HS-SCCH order may include indication bits that represent an order for informing the scheduling information from that node. This includes modulation, and TB size information, and also spreading codes used for scheduling. The indication bits may carry precoding and rank information if the interfere is scheduled with MIMO transmission. When the HS-SCCH order includes a UE ID, the node conveys the UE id's which are scheduled; so that the victim UE can decode its HS-SCCH and can get the scheduling information. [00064] Once the other UE signal is reconstructed ,the resultant signal will be subtracted from received signal, thereby reducing the interference caused by this UE signal.

[00065] FIG. 8 is a message sequence diagram showing messages exchanged between a node, Node-B (serving) 104, and a victim user equipment (UE) 106 during a data call setup. The information sent in the messaging shown in FIG. 8, includes sending the information such as the scheduled id during the TTI, and the transmission mode (non MIMO mode, MIMO mode, MIMO mode with single stream restriction), MIMO mode with four transmit antennas.

[00066] According to some embodiments, a procedure performed by the UE includes the victim UE detecting the HS-SCCH and decoding the HS-SCCH order, and extracting the UE id sent by the network and also the transmission mode. Once the transmission mode is known, the victim UE will decode the corresponding HS-SCCH of the interfering UE. Once the victim UE gets the scheduling information from that HS- SCCH, it will start to decode the signal from the received signal. In this case, interference cancellation can be applied.

[00067] Methods for Conveying Scheduling Information For Aiding

Interference Cancellation with Code Multiplexing

[00068] FIG. 9 is a schematic diagram illustrating a wireless communication system 900 with a heterogeneous network deployment showing interference caused by a macro node 102 on the user equipment (UE), UE2 908, connected to the low power node (LPN) 104. With reference to FIG. 9, a macro node 102 and a LPN 104 in a heterogeneous network 900 are shown. The macro node 102 is serving two UEs, UE1 906 and UE3 910, using code multiplexing, i.e., when scheduling the codes 1 -15 are shared between UE1 906 and UE3 910. In some embodiments, sharing means that codes 1 -M are used to schedule UE1 906 and codes M+1 -15 are used to schedule UE3 910. The M value lies between 2-14.

[00069] As shown in FIG. 9, UE2 908 is served by LPN 104. The performance of UE2 908 is impacted due to the strong interference from macro node 102.

[00070] With network assistance, the macro node 102 can transmit scheduling information/ UE identity using common HS-SCCH order or a new signal to the victim UE, which is UE2 (908). Since the macro node 102 is serving two UEs, UE1 (906) and UE3 (910), a determination must be made regarding which scheduling information/UE id should be transmitted.

[00071] As described below, the macro node 102 (or the aggressor node) will convey the information of the UE which has the lowest geometry (or long term SINR or path loss), for example UE3 910. Referring now to FIG. 10, FIG. 10 is a schematic diagram illustrating a wireless communication system with a heterogeneous network deployment showing a simulation scenario using network assistance. FIG. 10 shows a LPN 1004 serving a UE in positions L1 -L6, while the macro node 1002 is serving a UE at positions L7-L12. With reference to the network assistance simulation scenario shown in FIG. 10, it was discovered that the network assistance is useful when the macro node 1002 is serving far away UEs or the low geometry UEs (L12, L1 1 , and L9). When the macro node 1002 is serving nearby UEs or high geometry UEs (L7, L8 and L10), the victim UE which is connected to the LPN 1004 cannot decode the signal from the macro node 1002. As an example, the SINR or path loss may be used to determine the low geometry UEs.

[00072] As described in detail below, to aid in cancelling or reducing such interference, with code multiplexing, the aggressor node can send the scheduling information/id of the UE which has the lowest geometry to the victim UE, UE2 908.

[00073] A flow chart for an embodiment of an algorithm used in an exemplary method according to certain embodiments is shown in FIG. 1 1 . The node B scheduler decides whether code multiplexing has to be performed or not. This determination may depend on, for example, available power, available data load of the cell, etc. For example, if the available data for a first user is low (i.e., first user needs only 5 codes), then the remaining codes (i.e., 10) may be given to another user.

[00074] If the Node B decides not to have code multiplexing, i.e., only one UE is scheduled, then the scheduling information is conveyed, for example, by sending a common HS-SCCH order or a broadcasting signal or a dedicated signal etc.

[00075] If the node B decides to schedule multiple UEs in a single TTI, the node B first needs to identify the geometries of those UEs. There are many methods that may be used to find the geometry of the UEs. Three exemplary techniques that can be used are provided.

[00076] Method 1 : Based on Downlink scheduling

[00077] In some embodiments, at the ith TTI, the node B assigns a modulation scheme (with number of bits equal to Mi ) and the transport block size (such that code rate is equal to Ri). The geometry for a given UE can be computed as:

i = l [00078] Method 2: Based on CQI reporting bv UE

[00079] This method is similar to method 1 , but the averaging is done over the reported CQI by the UE.

N

[00080] GF = ∑ Bin2Dec(CQIi) /N

i = \

[00081 ] where Bin2Dec(CQIi) is the binary to decimal equivalent of 1^th CQI .

[00082] Method 3: Based on Uplink measurements

[00083] In some embodiments, from the uplink measurements, (i.e., UE traffic channels/control channels), the geometry of the UE can be determined based on received signal strength since the received signal strength is a function of the path loss.

[00084] Once the geometry is computed for the scheduled UEs, the node B chooses the UE which has the lowest geometry and will transmit the scheduling information for that UE using, for example, one or more of the methods that include either transmitting a broadcast channel, or dedicated channel or an HS-SCCH order.

[00085] Referring now to FIGS. 12 and 13, flow charts 1200 and 1300,

respectively, illustrate exemplary embodiments of methods performed by a first node for aiding cancellation of interference in a first mobile device communicating with a second node caused by the first node communicating with a plurality of mobile devices and operating in a cell in a heterogeneous communication network. In the flow charts of FIGS. 12 and 13, the steps are being performed by, for example, the macro node 102, thus being the first node, for aiding cancellation of interference in mobile device (908) communicating with a second node (e.g., low power node104). [00086] Referring now to FIG. 12, in the first step 1202, the first node (e.g., macro node 102) determines whether to use code multiplexing for communicating with the plurality of mobile devices (e.g., UE1 906, UE3 910). In step 1204, the first node (e.g., macro node 102) identifies if code multiplexing is used, and then, in step 1206, computes a geometry for each mobile device out of the plurality of mobile devices scheduled for communication with the first node (e.g., UE1 906, UE3 910). In step 1208, the first node (e.g., macro node 102) determines a scheduled mobile device, out of the plurality of mobile devices scheduled for communication with the first node (e.g., UE1 906, UE3 910), having the lowest geometry and then, in step 1210, transmits a first message to the first mobile device (e.g., UE2 908), wherein the first message includes scheduling information for the scheduled mobile device determined to have the lowest geometry (e.g., UE1 906). As described above, the first message may be transmitted using either transmitting a broadcast channel, or dedicated channel or an HS-SCCH order.

[00087] In some embodiments, the scheduling information includes at least one of (i) UE identities for the UEs scheduled for communication with the first node (102), (ii) modulation information, (iii) a transport block size, and (iv) a number of codes.

Furthermore, in some embodiments, the geometry for each mobile device of the plurality of mobile devices scheduled for communication is computed based on one or more of downlink, DL, scheduling, channel quality information, CQI, reporting by each mobile device of the plurality of mobile devices scheduled for communication with the first node, and uplink measurements. Furthermore, in some embodiments, the first message is a high speed shared control channel, HS-SCCH, order. Additionally, in some embodiments, the code multiplexing is based on one of an available power and an available data load of the cell.

[00088] Referring now to FIG. 13, in the first step 1302, the first node (e.g., macro node 102) determines whether to use code multiplexing for communicating with the plurality of mobile devices (e.g., UE1 906, UE3 910). In step 1304, the first node (e.g., macro node 102) identifies if code multiplexing is not used, and then, in step 1306, transmits a second message to the first mobile device (e.g., UE2 908), wherein the second message includes scheduling information for a second mobile device (e.g., UE1 906) scheduled for communication with the first node (e.g., macro node 102). As described above, the second message may be transmitted using, for example, either a transmitting broadcast channel, or dedicated channel or an HS-SCCH order.

[00089] Exemplary methods describing the steps performed in the first mobile device (e.g., UE2 908), which is the victim UE, to cancel or reduce interference using the received scheduling information includes the victim UE detecting the HS-SCCH and decoding the HS-SCCH order, and extracting the UE id sent by the network and also the transmission mode, where once the transmission mode is known, the victim UE will decode the corresponding HS-SCCH of the interfering UE. Furthermore, once the victim UE gets the scheduling information from that HS-SCCH, it will start to decode the signal from the received signal. In this case, interference cancellation can be applied.

[00090] As described above, in certain embodiments, scheduling information that is transmitted by the first node (e.g., macro node 102) may include UE IDs for the UEs scheduled for communication with the first node (e.g., macro node 102). [00091] As described above, in certain embodiments, the geometry for each mobile device out of the plurality of mobile devices scheduled for communication with the first node may be computed based on one or more of downlink (DL) scheduling, channel quality information (CQI) reporting by each mobile device of the plurality of mobile devices scheduled for communication with the first node, and uplink

measurements.

[00092] As described above, in certain embodiments, the first message

transmitted by the first node {e.g., macro node 102) may be a high speed shared control channel (HS-SCCH) order.

[00093] FIG. 14 illustrates a block diagram of an exemplary access node, also denoted first node, such as node 102 in FIG 1 , or second node herein, such as node 104 shown in FIG. 1 . As shown in FIG. 14, the access node 1404 may include: a data processing system 1402, which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), field- programmable gate arrays (FPGAs), and the like; a network interface 1410; a

transceiver 1404, and a data storage system 1406, which may include one or more nonvolatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). According to some embodiments, the data processing system 1402 may comprise a control unit used for selection of transmission parameters.

[00094] In embodiments where data processing system 1402 includes a

microprocessor, computer readable program code (CRPC) 1408 may be stored in a computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), and the like. In some embodiments, computer readable program code is configured such that when executed by a processor, the code causes the data processing system 1402 to perform steps described above (e.g., steps described above with reference to the flow charts shown in FIGS. 1 1 -13). In other embodiments, the access node 102, 104 is configured to perform steps described herein without the need for code. That is, for example, data processing system 1402 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of the access node 102, 104 described above may be implemented by data processing system 1402 executing computer instructions, by data processing system 1402 operating independent of any computer instructions, or by any suitable combination of hardware and/or software.

[00095] FIG. 15 illustrates a block diagram of an exemplary wireless device, such as device 106 shown in FIG. 1 and mobile devices 906, 908, 910 shown in FIG. 9. As shown in FIG. 15, the mobile device 106, 906, 908, 910 may include: a data processing system 1502, which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like; a transceiver 1504, and a data storage system 1506, which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). According to some

embodiments, the data processing system 1502 may comprise a control unit used for selection of transmission parameters. [00096] In embodiments where data processing system 1502 includes a microprocessor, computer readable program code (CRPC) 1508 may be stored in a computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), and the like. In some embodiments, computer readable program code is configured such that when executed by a processor, the code causes the data processing system 1502 to perform steps described above. In other embodiments, the mobile device 106, 906, 908, 910 is configured to perform steps described herein without the need for code. That is, for example, data processing system 1502 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of the mobile device 106, 906, 908, 910 described above may be implemented by data processing system 1502 executing computer instructions, by data processing system 1502 operating independent of any computer instructions, or by any suitable combination of hardware and/or software.

[00097] FIG. 16 illustrates a block diagram of an exemplary control node, such as central controller 404 shown in FIG. 4. As shown in FIG. 16, the control node 404 may include: a data processing system 1602, which may include one or more

microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like; a network interface 1606, and a data storage system 1604, which may include one or more nonvolatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). According to some embodiments, the data processing system 1602 may comprise a control unit used for selection of transmission parameters.

[00098] In embodiments where data processing system 1602 includes a microprocessor, computer readable program code (CRPC) 1608 may be stored in a computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), and the like. In some embodiments, computer readable program code is configured such that when executed by a processor, the code causes the data processing system 1602 to perform steps described above. In other embodiments, the control node 404 is configured to perform steps described herein without the need for code. That is, for example, data processing system 1602 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of the control node described above may be implemented by data processing system 1602 executing computer instructions, by data processing system 1602 operating independent of any computer instructions, or by any suitable

combination of hardware and/or software.

[00099] The methods, devices, and computer program products for conveying scheduling information for aiding interference cancellation in a code multiplexed wireless communication system described herein provide, among other things, for significant gains by using network assistance even when the aggressor UE is serving more than one UE. The methods, devices, and computer program products described herein further avoid the need to send multiple HS-SCCH orders, thereby saving power which can be utilized for improving cell performance. In addition, the methods, devices, and computer program products described herein provide a power efficient and code efficient solution for conveying information about the aggressor UE.

Abbreviations

3GPP 3rd Generation Partnership Project

ACK Acknowledgement

CC Chase combining

CQI Channel Quality Information

CRC Cyclic redundancy check

D-CPICH Demodulation (dedicated) Common Pilot Channel

DL Downlink

E-TFCI Enhanced TFCI

GSM Global System for Mobile Communications

HARQ Hybrid automatic repeat request

HSDPA High Speed Downlink Packet Access

HS-DPCCH High Speed dedicated physical common control channel

HSPA High Speed Packet Access

HS-PDSCH High speed Physical data shared channel

HS-SCCH High Speed Shared Control Channel

IR Incremental Redundancy

LPN Low Power Node

LTE Long Term Evolution

MIMO Multiple-Input Multiple-Out-put MMSE Minimum Mean Square Error

NAK Non-acknowledgement

PCI Precoding control index

P-CPICH Primary Common Pilot Channel

RAM Random Access Memory

ROM Read Only Memory

SIMO Single input multiple output

TFCI Transmit Format Combination Indicator

TTI Transmit Time Interval

Tx Transmitter

UE User Equipment

USB Universal Serial Bus

WCDMA Wideband Code Division Multiple Access

WiMax Worldwide Interoperability for Microwave Access

H-RNTI High Speed Radio Network Temporary Identifier

RND Radio Network Controller

TB Transport Block

ID Identifier

W Watt

[000100] In the above-description of various embodiments of present inventive concepts, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of present inventive concepts. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which present inventive concepts belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense expressly so defined herein.

[000101] When an element is referred to as being "connected", "coupled",

"responsive", or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected", "directly coupled", "directly responsive", or variants thereof to another element, there are no intervening elements present. Like numbers refer to like elements throughout.

Furthermore, "coupled", "connected", "responsive", or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term "and/or" includes any and all combinations of one or more of the associated listed items.

[000102] It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another element/operation. Thus, a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of present inventive concepts. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification.

[000103] As used herein, the terms "comprise", "comprising", "comprises", "include", "including", "includes", "have", "has", "having", or variants thereof are open-ended, and include one or more stated features, integers, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, integers, elements, steps, components, functions or groups thereof. Furthermore, as used herein, the common abbreviation "e.g.", which derives from the Latin phrase "exempli gratia," may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation "i.e.", which derives from the Latin phrase "id est," may be used to specify a particular item from a more general recitation.

[000104] Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or non-transitory computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s).

[000105] These computer program instructions may also be stored in a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as "circuitry," "a module" or variants thereof.

[000106] It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

[000107] Many variations and modifications can be made to the embodiments without substantially departing from the principles of the present inventive concepts. All such variations and modifications are intended to be included herein within the scope of present inventive concepts. Accordingly, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments, which fall within the spirit and scope of present inventive concepts. Thus, to the maximum extent allowed by law, the scope of present inventive concepts are to be determined by the broadest permissible interpretation of the present disclosure including the following examples of embodiments and their equivalents, and shall not be restricted or limited by the foregoing detailed description.

Claims

1 . A method, performed by a first node (102) for aiding cancellation of interference in a first mobile device (908) communicating with a second node (104), the interference caused by the first node (102) communicating with a plurality of mobile devices (906, 910) and operating in a cell (302) in a heterogeneous communication network, the method comprising:

determining (1202, 1302), in the first node (102), whether to use code

multiplexing for communicating with the plurality of mobile devices (906, 910);

when code multiplexing is used, then:

computing (1306), in the first node (102), a geometry for each mobile device out of the plurality of mobile devices (906, 910) scheduled for

communication with the first node (102);

determining (1308), in the first node (102), a scheduled mobile device, out of the plurality of mobile devices (906, 910), having the lowest geometry; and transmitting (1310), from the first node (102), a first message to the first mobile device (908), wherein the first message includes scheduling information for the scheduled mobile device determined to have the lowest geometry.

2. The method according to claim 1 , wherein when code multiplexing is not used, then:

transmitting (1206), from the first node (102), a second message to the first mobile device (908), wherein the second message includes scheduling information for a second mobile device scheduled for communication with the first node (102).

3. The method according to any one of claims 1 or 2, wherein the second node (104) is a low power node and the first node (102) is a macro node.

4. The method according to any one of claims 1 to 3, wherein the mobile devices are user equipments, UEs, and the scheduling information includes at least one of (i) UE identities for the UEs scheduled for communication with the first node (102), (ii) modulation information, (iii) a transport block size, and (iv) a number of codes.

5. The method according to any one of claims 1 to 4, wherein the geometry for each mobile device of the plurality of mobile devices (906, 910) scheduled for communication is computed based on one or more of downlink, DL, scheduling, channel quality information, CQI, reporting by each mobile device of the plurality of mobile devices (906, 910) scheduled for communication with the first node (102), and uplink measurements.

6. The method according to any one of claims 1 to 5, wherein the first message is a high speed shared control channel, HS-SCCH, order.

7. The method according to any one of claims 1 to 6, wherein the

determination of whether to use code multiplexing is based on one of an available power and an available data load of the cell.

8. A first node (102) for aiding cancellation of interference in a first mobile device (908) communicating with a second node (104), the first node (102) configured to communicate with a plurality of mobile devices (906, 910) and being operable in a cell (302) in a heterogeneous communication network , the first node (102) comprising: a processor (1402);

a memory (1406) coupled to the processor (1402);

a network interface (1410) coupled to the processor (1402);

a transceiver (1404) coupled to the network interface (1410); and

an antenna coupled to the transceiver (1404) configured to transmit and receive messages;

wherein the processor (1402) is configured to:

determine whether to use code multiplexing for communicating with the plurality of mobile devices (906, 910);

when code multiplexing is used:

compute a geometry for each mobile device out of the plurality of mobile devices (906, 910) scheduled for communication with the first node

(102);

determine a scheduled mobile device, out of the plurality of mobile devices (906, 910), having the lowest geometry; and

transmit a first message to the first mobile device (908), wherein the first message includes scheduling information for the scheduled mobile device determined to have the lowest geometry.

9. The first node (102) according to claim 8, wherein when code multiplexing is not used, the processor (1402) is configured to:

transmit a second message to the first mobile device (908), wherein the second message includes scheduling information for a second mobile device scheduled for communication with the first node (102).

10. The first node (102) according to any one of claims 8 or 9, wherein the second node (104) is a low power node and the first node (102) is a macro node.

1 1 . The first node (102) according to any one of claims 8 to 10, wherein the mobile devices are user equipments, UEs, and the scheduling information includes at least one of (i) UE identities for the UEs scheduled for communication with the first node (102), (ii) modulation information, (iii) a transport block size, and (iv) a number of codes.

12. The first node (102) according to any one of claims 8 to 1 1 , wherein the geometry for each mobile device of the plurality of mobile devices (906, 910) scheduled for communication is computed based on one or more of downlink, DL, scheduling, channel quality information, CQI, reporting by each mobile device of the plurality of mobile devices (906, 910) scheduled for communication with the first node (102), and uplink measurements.

13. The first node (102) according to any one of claims 8 to 12, wherein the first message is a high speed shared control channel, HS-SCCH, order.

14. The first node (102) according to any one of claims 8 to 13, wherein the determination of whether to use code multiplexing is based on one of an available power and an available data load of the cell.