Patent Description:
Mobile communication networks typically comprise a plurality of cells, wherein each cell is divided into a plurality of S sectors. Each cell is further served by a base station (BS), which is equipped with a plurality of M directional antennas, where groups of M/S antennas point in the direction of each of the sectors of the cell. A common mobile communication network has a hexagonal cell model, wherein each cell is divided into three sectors, i.e. wherein S = <NUM>. BSs can communicate with each other over dedicated backhaul links that connect them among each other. In the uplink, this allows the BSs to exchange information about their receive signals. Exchanging such information can improve a decoding performance of decoding messages included in the receive signals, because communications in neighboring BSs interfere with each other. Access to the receive signals of multiple BSs allows increasing diversity (i.e. two looks at the same input) and thus eliminating interference.

In a quantize-and-share decoding method, some BSs quantize the receive signals, particularly messages received from terminals, in their sectors, and send the quantization information to their neighboring BSs. Decoding of the messages is performed at specific BSs of cells that are called "master cells". Specifically, each master cell collects quantization information from some of the adjacent cell sectors, and jointly decodes the messages signals in its own cell and the messages in these sectors. The decoded signals are then sent back over the backhaul links to the BSs that are interested in these messages.

A straightforward approach to incorporate such cooperative decoding between BSs is to identify master cells according to a tightest packing in the cell-layout of the network, which ensures that each master BS is surrounded by one ring of ordinary cells pertaining exclusively to this master cell. A master cell and the surrounding cells will then form a cluster. For decoding, each BS in a surrounding ring sends a quantized version of all receive signals in its plurality of sectors to the master cell, which then jointly decodes all the messages transmitted in the master cell and in the cells in the surrounding rings. The decoded messages are then sent back to their intended BSs.

In practice, however, a cooperative decoding between BSs is implemented based on an "opportunistic <NUM>-sector decoding" rule. Specifically, to decode the messages sent at a given mobile user, one chooses three sectors opportunistically and the message is decoded based on the received signals in these three sectors. Signals pertaining to messages sent in other sectors are treated as noise. The three sectors are chosen among the set of sectors formed by the sector of the mobile user sending the message and all its adjacent sectors, with the goal to minimize the probability of a decoding error. Each decoded message is sent back to its intended BS.

A disadvantage of both the straightforward approach and the opportunistic <NUM>-sector decoding approach implemented in practice is that a decoding performance is not optimized.

<CIT> discloses a wireless network system including a plurality of base stations each configured to manage active links to mobile stations within a range; and a controller configured to control the base stations to provide at least two of the active links from two different base stations simultaneously to a given mobile station in integral manner for joint processing.

<CIT> discloses methods proposed to address interference problems in wireless networks, with two promising methods being: Network Multi-Input-Multi-Output decoding and Multi-Cell Successive Interference Cancellation.

<CIT> discloses a method and system for identifying cell clusters within a coordinated multiple point wireless transmission network, wherein the network includes a total number of cells served by corresponding base stations and a base station controller divides the network of cells into clusters in order to reduce scheduling complexity while optimizing throughout and performance.

Embodiments representing specific realisations of the invention are defined in the dependent claims.

In view of the above-mentioned disadvantage, the present invention aims to improve the conventional approaches for joint decoding. The present invention has the object to provide a way to further improve the decoding performance. To this end, the present invention intends to minimize the interference caused by transmissions from outside the master cell. In particular, an intention of the invention is thus to cluster sectors that yield the best decoding performance under a cooperative decoding algorithm.

In the following, parts of the description and drawings referring to embodiments not covered by the claims, are not part of the invention, but are illustrative examples necessary for understanding the invention.

In particular the present invention proposes a new cooperative (joint) decoding algorithm at the BSs of a sectorized cellular system, in particular a system with a hexagonal cell layout. The main idea of the invention is to partition the entire network into disjoint, wind-spinner-shaped clusters of sectors, where the center cells of these clusters act as master cells. Within each wind-spinner cluster, all receive signals of sectors not pertaining to the master cell may be quantized, and are sent to the master cell which jointly decodes all messages in the sectors of this wind-spinner cluster. Interference from sectors outside the wind-spinner clusters is treated as noise. The invention has the further advantage that communication of messages over backhaul is reduced, or for an unchanged level the performance of decoding is improved.

A first aspect of the invention provides a decoding module for a primary base station in a network comprising a plurality of base stations, each base station serving a cell and each cell being partitioned into a plurality of sectors, the primary base station serving a first cell and the decoding module being configured to receive information from each of a plurality of secondary base stations each serving a respective second cell adjacent to the first cell, wherein the information is representative of at least one message originating from at least one terminal located in the respective second cell of a secondary base station in one specific sector adjacent to the first cell, and jointly decode the information sent from the secondary base stations and at least one message originating from at least one terminal located in the first cell.

Due to the selection of the specific sectors of the second cells and the sectors of the first cell, from which messages are jointly decoded by the decoding module, the interference can be reduced, and the decoding performance can thus be optimized significantly.

The information, which the decoding module is configured to jointly decode, originates from terminals located in a cluster of sectors. "Cluster" as used herein with reference to the invention may have a specific meaning, such as the cluster includes the sectors of the first cell and the specific sectors of the second cells adjacent to the first cell.

The formed cluster of sectors leads to a significant increase in decoding performance of the messages at the decoding module.

The specific sectors of the second cells in the cluster form disjoint pairs of adjacent sectors.

In other words, two specific sectors of second cells may be adjacent to each other and form a pair. However, different pairs are disjoint from another, i.e. not adjacent. That means that there are not more than two adjacent sectors of the second cells. This leads to a wind-spinner shape of the cluster in a hexagonal cell layout. The wind-spinner cluster consists of the sectors of the first cell and the different pairs of sectors of the second cells, the latter sectors forming leaf-like structures connected to the hexagonal first cell.

Although described herein as a "wind-spinner" shape, various shapes are within the scope of the invention. Wind-spinners may also be known as windmill shape, pinfoil shape or whirligig shape. Described generally such shapes may comprise leaves originating from a central point and as a three dimensional structure would catch the wind and spin, hence "wind-spinner". In some preferred embodiments, the leaves extend generally outwardly from a central area, which may coincide with a center of rotation, such that preferably the wind-spinner shape possesses rotational symmetry of order n, where n may be <NUM>. The leaves or foils or blades of the wind-spinner shape may be mutually separated from each other in a rotational sense. Each leaf or foil or blade may be comprised of a sector of the first cell, and two mutually adjacent sectors of different second cells, in total comprising three sectors.

The wind-spinner shape and the cells, and their sectors are shown as regular shapes in the enclosed Figures, although it will be understood that this is merely a preferred network model. Other non-regular shaped network models and real life networks with other shapes or combinations of shapes are within the scope of the invention.

In a further implementation form of the first aspect, the decoding module is configured to send, e.g. over a backhaul connection, information representing a decoded message back to the secondary base station that sent the information representing the message to the decoding module.

A second aspect of the present invention provides a primary base station incorporating the decoding module according to the first aspect or any of its implementation forms, wherein the primary base station is configured to receive the information from the secondary base stations over backhaul links.

The primary base station is accordingly configured to carry out the joint decoding of the messages, and achieves an optimized performance due to the reduced interference.

Another aspect of the present invention provides a network comprising a plurality of base stations, each base station serving a cell and each cell being partitioned into a plurality of sectors, wherein the plurality of base stations comprise a primary base station for serving a first cell and a plurality of secondary base stations each for serving a respective second cell adjacent to the first cell, each secondary base station is configured to send, to the primary base station, information representing at least one message originating from at least one terminal located in the respective second cell of the secondary base station in one specific sector adjacent to the first cell, and the primary base station is configured to jointly decode the information sent from the secondary base station and at least one message originating from at least one terminal located in the first cell.

The specific sectors of the second cells and the sectors of the first cell form a cluster of sectors. In a hexagonal cell layout this cluster has a wind-spinner shape. The selection of the sectors for the cluster leads to an improved decoding performance at the primary base station. By configuring the network this way, opportunistic choosing of sectors is also avoided.

In an implementation form of the fifth aspect, each cell is configured as a hexagonal cell and is partitioned, for example evenly, into three sectors, and the plurality of secondary base stations are six secondary base station serving six second cells adjacent to the first cell.

In a further implementation form of the fifth aspect, the cells of the network are arranged in a first direction, and a plurality of primary base stations are arranged in the first direction with a plurality of, in particular two, secondary base stations arranged between each two primary base stations.

In a further implementation form of the fifth aspect, the cells of the network are further arranged in a second direction, and a plurality of primary base stations are arranged in the second direction with at least one base station arranged between each two primary base stations.

The above implementation forms enable a partitioning of the network cell layout into clusters that lead to an improved decoding performance. In a hexagonal cell layout, wind-spinner shaped clusters can be distributed adjacently throughout the network cell layout.

Yet another aspect of the present invention provides a decoding method for a primary base station in a network comprising a plurality of base stations, each base station serving a cell and each cell being partitioned into a plurality of sectors, the primary base station serving a first cell and the method comprising receiving information from each of a plurality of secondary base stations each serving a respective second cell adjacent to the first cell, wherein the information is representative of at least one message originating from at least one terminal located in the respective second cell of a secondary base station in one specific sector adjacent to the first cell, and jointly decoding the information sent from the secondary base stations and at least one message originating from at least one terminal located in the first cell.

The information, which is jointly decoded, originates from terminals located in a cluster of sectors, and the cluster includes the sectors of the first cell and the specific sectors of the second cells adjacent to the first cell.

The method comprises sending information representing a decoded message back to the secondary base station that sent the information representing the message to the decoding module.

The method of the sixth aspect and its implementation forms achieves the same advantages and effects as the decoding module of the first aspect and its respective implementation forms.

A possible implementation of the present invention provides a computer program product comprising a program code for carrying out, when implemented on a processor, a method according to the sixth or the seventh aspect. The present invention may be performed on specially adapted or configured circuits or processors.

The computer program product accordingly enables achieving the same advantages and effects as described above for the methods of the sixth aspect or the seventh aspect, respectively. A computer program product according to the invention may also contain a program code for controlling a decoding module according to the first aspect, or a sending module according to the third aspect.

<FIG> shows a network <NUM> according to an embodiment of the present invention comprising a plurality of base stations (striped). In particular, <FIG> shows a primary base station <NUM> according to an embodiment of the present invention and four secondary base stations <NUM> according to embodiments of the present invention. Each base station serves a cell. The primary base station <NUM> serves a first cell <NUM>, and each of the secondary base stations <NUM> serves a second cell <NUM>. Each cell is partitioned into a plurality of sectors <NUM>, and each cell has accordingly a certain model shape. In <FIG> the cell model layout is arbitrary - and just for general and non-limiting illustrational purposes each cell is shown to be divided into four sectors <NUM> and having a square shape. Notably, however, a preferred cell model for the network <NUM> is a hexagonal cell model, in which each cell is hexagonal and is divided in three sectors <NUM> (as shown in the following <FIG>, <FIG> <FIG> and <FIG>).

The primary base station <NUM> includes a decoding module <NUM> according to an embodiment of the present invention. The decoding module <NUM> is configured to receive information <NUM> from each of a plurality of secondary base stations <NUM> serving a respective second cell <NUM> adjacent to the first cell <NUM>. The information <NUM> received from each secondary base station <NUM> is representative of at least one message <NUM> originating from at least one terminal <NUM> (terminals are indicated by black triangles) located in the respective second cell <NUM> of the secondary base station <NUM> in one (i.e. only one) specific sector <NUM> adjacent to the first cell <NUM>. The information <NUM> may comprise one or more of the messages <NUM>, or may be derived from at least one message <NUM>, e.g. by quantization. The decoding module <NUM> is further configured to jointly decode the information <NUM> sent from the secondary base stations <NUM> together with at least one message <NUM> originating from at least one terminal <NUM> located in the first cell <NUM>.

Each secondary base station <NUM> includes a sending module <NUM> according to an embodiment of the present invention. The sending module <NUM> is configured to send, to the primary base station <NUM> serving the first cell <NUM>, the information <NUM> representative of the at least one message <NUM> originating from the at least one terminal <NUM> located in the second cell <NUM> in one (i.e. only one) specific sector <NUM> adjacent to the first cell <NUM>.

In other words, considering the whole network <NUM>, each secondary base station <NUM> is configured to send, to the primary base station <NUM>, the information <NUM> related to a single determined sector <NUM> of its second cell <NUM>, and the primary base station <NUM> is configured to jointly decode this information <NUM> together with at least one message <NUM> originating from a terminal <NUM> located in its first cell <NUM>. The decoding performance of the primary base station <NUM> decoding the messages <NUM> and/or the information <NUM> indicative of the messages <NUM> is significantly improved compared to conventional joint decoding approaches.

<FIG> shows a network <NUM> according to a preferred embodiment of the present invention, which builds on the network <NUM> shown in <FIG>. Same elements in <FIG> and <FIG> are labelled with the same reference signs and function likewise. In particular, <FIG> shows a hexagonal cellular network model, i.e. with hexagonal cells and with three sectors <NUM> per cell. Boundaries of the hexagonal cells are depicted in <FIG> with thicker lines, and boundaries of sectors <NUM> inside a cell are depicted with thinner lines. Interference links between sectors <NUM> are also depicted by dashed lines. Further, the following is exemplarily assumed for the network <NUM> of <FIG>:.

In <FIG>, the BS antennas <NUM> pointing to a given sector <NUM> are depicted with a small circle.

In <FIG> particularly different cluster <NUM> of sectors <NUM> are shown. In the hexagonal cell model shown in <FIG>, wherein each cell is divided into three sectors <NUM>, these clusters <NUM> take the form of "wind-spinners". Different such clusters <NUM> in <FIG> are depicted in different shades of gray or white, and master cells (i.e. first cells <NUM> that are served by a primary base station <NUM>) are at the center of the clusters <NUM>, where the first cell <NUM> is indicated with a lighter color. Within each cluster <NUM>, all messages <NUM> originating from sectors <NUM> not pertaining to the first cell <NUM> are quantized (by a sending module <NUM> of a secondary base station <NUM>), and are sent to the first cell <NUM>, in which the decoding module <NUM> of the primary base station <NUM> jointly decodes all messages <NUM> in the sectors <NUM> of this cluster <NUM>. Notably, interference from sectors <NUM> outside the clusters <NUM> is treated as noise.

The "wind-spinner" shape of the clusters <NUM> in the hexagonal cell layout of the network <NUM> shown in <FIG> is due to the following selection of sectors <NUM> for the cluster <NUM>. Firstly, from each second cell <NUM>, only one specific sector <NUM> belongs to a given cluster <NUM>. Secondly, if a second cell <NUM> has two or more sectors <NUM> adjacent to the first cell <NUM>, the specific sector <NUM> is one having a predetermined position relative to the other sectors <NUM> of the second cell <NUM> adjacent to the first cell <NUM>. Thirdly, a cluster <NUM> includes the sectors <NUM> of the first cell <NUM> and the specific sectors <NUM> of all second cells <NUM> adjacent to the first cell <NUM>. Fourthly, the specific sectors <NUM> of the second cells <NUM> in the cluster <NUM> form disjoint pairs of adjacent sectors <NUM>.

<FIG> shows a network <NUM> according to an embodiment of the present invention, which builds on the network <NUM> shown in <FIG>. Same elements in <FIG> and <FIG> are labeled with the same reference signs and function likewise.

Like in <FIG>, also <FIG> illustrates the main ingredients of the invention in a cellular system, where cells have hexagonal shapes and are partitioned into three non-interfering sectors <NUM>. The set of cells is partitioned into two kinds of sets: a set of first cells <NUM> (master cells) and a set of second cells <NUM> (ordinary cells). <FIG> depicts the first cells <NUM> in dark grey and second cells <NUM> in white. Any cell that is not a first cell <NUM> is a secondary cell <NUM>.

In the vertical direction as indicated in <FIG> (here referred to as "S-N" direction") every third cell of the hexagonal cell model is a first cell <NUM>, and the first cells <NUM> are chosen such that no two first cells <NUM> are adjacent to each other. Specifically, the cell of the network <NUM> are arranged in a first (S-N) direction, and a plurality of first cells <NUM> are arranged in the first direction with a plurality of, in particular two, second cells <NUM> arranged between each two first cells <NUM>. Further, the cells of the network <NUM> are further arranged in a second direction (here a horizontal direction referred to as "E-W" direction), and a plurality of first cells <NUM> are arranged in the second direction with at least one first cell <NUM> and/or second <NUM> arranged between each two first cells <NUM>.

A main ingredient of the invention is the definition of the clusters <NUM>, and the choice of letting one specific primary base station <NUM> decode all messages <NUM> originating from a cluster <NUM>. In particular, a cluster <NUM> is formed around each of the first cells <NUM> according to the following steps:.

This yields a cluster <NUM> in the form of a wind-spinner as shown as in <FIG>, where the first cell <NUM> is indicated with a white snake-like line. The sectors <NUM> of the cluster <NUM> of the different second cells <NUM> adjacent to the first cell <NUM> form "leaves" arranged around the first cell <NUM>. It can be seen that the sectors <NUM> of the second cells <NUM> come in adjacent pairs. In total three disjoint pairs form the sectors <NUM> of the second cells <NUM>.

<FIG> shows a flow diagram of steps performed at a primary base station <NUM> of a first cell <NUM> or performed at a secondary base station <NUM> of a second cell <NUM>.

In particular, if the base station of a cell is a primary base station <NUM> serving a first cell <NUM>, it collects the information <NUM> preferably in the form of quantized messages <NUM> pertaining to the other sectors <NUM> of the same cluster <NUM>. Based on the collected quantized messages <NUM> and on messages <NUM> received in the sectors <NUM> of its own first cell <NUM>, it jointly decodes all the messages <NUM> of sectors <NUM> pertaining to the same cluster <NUM>. Then, it sends the decoded messages <NUM> originating from second cells <NUM> back to the secondary base station <NUM>, preferably over backhaul links.

If the base station of a cell is a secondary base station <NUM> serving a second cell <NUM>, it sends preferably quantization information as the information <NUM> indicative of messages <NUM> received for its specific sector <NUM> to the primary base station <NUM> of the first cell <NUM> of the respective cluster <NUM>. Then, it waits for its neighboring primary base stations <NUM> to decode the messages <NUM>.

In the following, an exemplary embodiment according to the present invention is described in detail with respect to <FIG> specifically shows a network <NUM> according to an embodiment of the present invention. Terminals <NUM> in the network <NUM> transmit their messages <NUM> using traditional multi-antenna point-to-point codes subject to an input power constraint. No channel state-information is required at the terminals <NUM>. The decoding algorithm run at each of the various BSs <NUM>, <NUM> of the network <NUM> depends on the position of the respective BS in the network <NUM>.

In <FIG> a cell coordinate system (rows, columns) is used and the sector labels (a), (b), (c) are introduced. Cells, whose centers are in the rows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. are first cells <NUM>. Cells, whose centers are in the rows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. are second cells <NUM>. Steps performed at the different BSs are now described, first for secondary base stations <NUM> serving second cells <NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas <NUM> of its sector (a) <NUM>, and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j-<NUM> and column <NUM>-<NUM>. A Gaussian vector quantizer or a scalar quantizer is used for these quantization steps and for all following quantization steps.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas <NUM> of its sector (b) <NUM>, and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j-<NUM> and column l+<NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas <NUM> of its sector (c) <NUM>, and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j+<NUM> and column l.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas <NUM> of its sector (a) <NUM>, and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j+<NUM> and column <NUM>-<NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas <NUM> of its sector (b) <NUM>, and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j-<NUM> and column l.

The secondary base station <NUM> of the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas <NUM> of its sector (c) <NUM>, and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j+<NUM> and column l+<NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas of its sector (a), and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j-<NUM> and column l-<NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas of its sector (b), and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j-<NUM> and column l+<NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas of its sector (c), and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j+<NUM> and column l.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas of its sector (a), and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j+<NUM> and column <NUM>-<NUM>.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas of its sector (b), and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j-<NUM> and column l.

The secondary base station <NUM> in the second cell <NUM> of row j and column l quantizes the outputs received at the M/<NUM> antennas of its sector (c), and sends the quantization information over a backhaul link to the primary base station <NUM> of the first cell <NUM> in row j+<NUM> and column l+<NUM>.

The secondary base stations <NUM> of the second cells <NUM> that lie in the rows <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc. then wait until their neighboring primary base stations <NUM> have decoded their intended messages <NUM>, and inform them about the results over the backhaul links.

Next are described the decoding operations at the primary base station <NUM> of the first cells <NUM>.

The primary base station <NUM> in the first cell <NUM> of row j and column l performs the following steps: it uses the <NUM> pieces of quantization information received from its <NUM> neighboring secondary base stations <NUM> over the backhaul link to reconstruct quantized versions of the messages <NUM> received at the M/<NUM> antennas <NUM> of the sector (a) <NUM> of the two second cells <NUM> in rows j-<NUM> and j+<NUM> and column l+<NUM>, the sector (b) <NUM> of the second cell <NUM> in row j+<NUM> and column l-<NUM> and the second cell <NUM> in row j+<NUM> and column l, and the sector (c) <NUM> of the second cell <NUM> in row j-<NUM> and column l-<NUM> and the second cell <NUM> in row j-<NUM> and column l.

The primary base station <NUM> then uses these reconstructed quantized signals and the outputs at the <NUM> antennas <NUM> of its own first cell <NUM>, to jointly decode the messages <NUM> sent in the sectors (a), (b), (c) of its own first cell <NUM> and the messages <NUM> sent in the <NUM> sectors <NUM> of the second cells <NUM> described above. Then, it sends the messages <NUM> decoded for the sectors of adjacent second cells <NUM> over the backhaul links back to the secondary base stations <NUM> of these adjacent second cells <NUM>.

<FIG> shows a decoding method <NUM> according to an embodiment of the present invention. The method <NUM> may be carried out by a decoding module of a base station (e.g. the decoding module <NUM> shown in <FIG>) or by a primary base station <NUM>. The method <NUM> includes, for a primary base station <NUM> in a network <NUM> comprising a plurality of base stations, each base station serving a cell and each cell being partitioned into a plurality of sectors, the primary base station serving a first cell: receiving <NUM> information <NUM> from each of a plurality of secondary base stations <NUM> each serving a respective second cell <NUM> adjacent to the first cell <NUM>, wherein the information <NUM> is representative of at least one message <NUM> originating from at least one terminal <NUM> located in the respective second cell <NUM> of a secondary base station <NUM> in one specific sector <NUM> adjacent to the first cell <NUM>, and jointly decoding <NUM> the information <NUM> sent from the secondary base stations <NUM> and at least one message <NUM> originating from at least one terminal <NUM> located in the first cell <NUM>.

<FIG> shows a sending method according to an embodiment of the present invention. The method may be carried out by a sending module of a base station (e.g. the sending module <NUM> shown in <FIG>) or by a secondary base station <NUM>. The method <NUM> includes, for a secondary base station <NUM>) in a network <NUM> including a plurality of base stations, each base station serving a cell and each cell being partitioned into a plurality of sectors, the secondary base station serving a second cell: sending <NUM> to a primary base station <NUM> serving a first cell <NUM>, information <NUM> representative of at least one message <NUM> originating from at least one terminal <NUM> located in the second cell <NUM> in one specific sector <NUM> adjacent to the first cell <NUM>.

In the following, a numerical comparison on a Rayleigh Fading Channel is presented with respect to <FIG>. In particular, the rates achieved with the new wind-spinner clustering approach described above are numerically compared to the rates achieved by the "opportunistic <NUM>-best sectors" approach currently used in practice (referred to as benchmark scheme). Improvements are important at moderate and high SNR, because the wind-spinner clustering approach of the present invention allows reducing the inter-cluster interference (which is treated as noise) that stems from terminals <NUM> in sectors <NUM> pertaining to different clusters <NUM>. The simulation in <FIG> is based on the following assumptions:.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word "comprising" does not exclude other elements or steps and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claim 1:
Decoding module (<NUM>) for a primary base station (<NUM>) in a network (<NUM>) comprising a plurality of base stations (<NUM>, <NUM>), each base station (<NUM>, <NUM>) serving a cell (<NUM>, <NUM>) and each cell (<NUM>, <NUM>) being partitioned into a plurality of sectors (<NUM>), the primary base station (<NUM>) serving a first cell (<NUM>) and the decoding module (<NUM>) being configured to
receive information (<NUM>) from each of a plurality of secondary base stations (<NUM>) each serving a respective second cell (<NUM>) adjacent to the first cell (<NUM>),
wherein the information (<NUM>) is representative of at least one message (<NUM>) originating from at least one terminal (<NUM>) located in the respective second cell (<NUM>) of a secondary base station (<NUM>) in one specific sector (<NUM>) adjacent to the first cell (<NUM>), and
jointly decode the information (<NUM>) sent from the secondary base stations (<NUM>) and at least one message (<NUM>) originating from at least one terminal (<NUM>) located in the first cell (<NUM>), wherein
the information (<NUM>), which the decoding module (<NUM>) is configured to jointly decode, originates from terminals (<NUM>) located in a cluster (<NUM>) of sectors (<NUM>), and
the cluster (<NUM>) includes the sectors (<NUM>) of the first cell (<NUM>) and the specific sectors (<NUM>) of the respective second cells (<NUM>) adjacent to the first cell (<NUM>), characterised in that
if a respective second cell (<NUM>) has two or more sectors (<NUM>) adjacent to the first cell (<NUM>), the one specific sector (<NUM>) adjacent to the first cell (<NUM>) has a predetermined position relative to the other sectors (<NUM>) of the respective second cell (<NUM>) adjacent to the first cell (<NUM>), and wherein
the specific sectors (<NUM>) of the respective second cells (<NUM>) in the cluster (<NUM>) form disjoint pairs of adjacent sectors (<NUM>).