WO2012062349A1 - Radio base station, network nodes, and methods for transmitting data in a radio communications system - Google Patents

Abstract

The present invention refers to transmitting data in a radio communications system. In particular, methods and devices are presented for transmitting data in a radio communications system, comprising transmitting, from a radio base station or a network node, the radio base station spanning a cell, to a further network node, cell capability information, wherein the cell capability information comprises - a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed; - a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed; - a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

Description

DESCRIPTION

Radio base station, network nodes, and methods for

transmitting data in a radio communications system

FIELD OF THE INVENTION

The present invention relates to transmitting data in a radio communications system. Particularly, the present invention refers to methods for said transmitting; a radio base station configured to perform said transmitting; and network nodes configured to perform said transmitting.

BACKGROUND OF THE INVENTION

One type of radio communications systems are Code-Division Multiple Access (CDMA) systems. A CDMA system allows several transmitters to send data sequences in form of signals simultaneously over a single communication channel by

modulating those signals onto a single carrier frequency. The signals are separated from each other into radio channels by means of specific codes, called channelization codes. Each user in the CDMA system is assigned a code which is used to transform a user' s narrow bandwidth signals into signals with a wider bandwidth, e.g., by binary multiplying the data sequence with the chosen code, which typically has a much larger bandwidth than the original signal. In other words, the signal is spread in the frequency domain. For this reason, the channelization codes are also called spreading codes. The bits in the spreading code are called chips to differentiate them from the bits in the data sequence, which are called symbols. The receiver then uses the same spreading code to transform the spread-spectrum signal back into the original user's data stream.

The total allocated bandwidth in a CDMA system can be divided into several smaller frequency channels. For example, certain frequency channels could be used exclusively for downlink transmission from the radio base station to the mobile station, while other frequency channels could be reserved for uplink transmission from the mobile station to the radio base station. That is, a station's transmitter and receiver operate at different carrier frequencies. This scheme is called frequency-division duplex (FDD) mode. The

communication in uplink and downlink can also be separated in time, i.e., during downlink transmission there is no uplink transmission and vice versa. This transmission method is called time-division duplex (TDD) .

There exist many mobile communication standards that use CDMA as an underlying channel access method, e.g., IS-95,

CDMA2000, and Wideband-CDMA (W-CDMA) . In W-CDMA, the carriers typically have a bandwidth of 5 MHz. Each carrier can be divided into radio frames, and each frame can further be divided into time slots. A typical frame length is 10 ms, and a typical number of slots per frame is 15. There are different types of channels specified in W-CDMA, e.g., logical channels, transport channel, and physical channels. Logical channels define the type of data that is to be transferred, e.g., data or control information. Transport channels define how and with what characteristics the data is transferred by the physical layer. Transport channels are typically unidirectional whereas logical channel can also be bidirectional. Some types of transport channels can exist in both the uplink and downlink direction, but they are still separate channels. Logical and transport channels can be divided, e.g., into control channels and traffic channels. A control channel can be either common or dedicated. A common channel is a point-to-multipoint channel and common to all users in a radio cell. A dedicated channel is a point-to- point channel used by only one user. Physical channels define the exact physical characteristics of the radio channels. The network may not assign a dedicated channel for every user. Some of the W-CDMA channels can be shared by more than one user in order to allow a more efficient use of the frequency spectrum. If the data traffic is low, or if the data is sent in bursts instead of a stream of nearly constant rate, then shared channels could be used instead of dedicated channels. The shared channel is open to be used by every user, and each user can request a temporary allocation for a short time using a specific resource reservation procedure. The access to the channel is granted by a scheduling function in the network. Thus a shared channel can be used by only one active user at a time, but that user may change frequently. The high speed downlink shared channel (HS-DSCH) is an example of a common transport channel that can be shared by several users.

The mobile stations should not transmit using fixed power levels, because the signals received from mobile stations farer away from the radio base station would then be weaker than signals received from close by mobile stations, and may thus not be heard by the radio base station because the uplink signals interfering with each other. The mobile stations far away from the radio base station should transmit with considerably higher power than mobiles close to the base station. In the downlink direction the signals transmitted by one radio base station are orthogonal. Signals that are mutually orthogonal do not interfere with each other.

However, in practice full orthogonality cannot be achieved because signal reflections may change the signal such that it is no longer orthogonal. Also, signals sent from other radio base stations are not orthogonal and therefore may cause interference. Therefore, it might be necessary to also control the power in the downlink direction.

The communications protocol between the radio base stations and the mobile stations, also referred to as the air- interface, has a layered structure in W-CDMA. The lowest layer in this interface is the physical layer. Layer 2 typically comprises the medium access control (MAC) , the radio link control (RLC) , the broadcast multicast control (BMC) , and the packet data convergence protocol (PDCP) sub layers. Layer 3 includes the radio resource control (RRC) , amongst others.

The chip rate in W-CDMA is typically 3.84 Mchip/s, but there are also other chip rates specified. A radio frame is divided into time slots, which results in a certain number N of chips per slot. Hence one time slot could transfer N symbols.

However, this chip rate is the total data rate available, whereas the rate with which symbols can be transferred to one user depends on the code used to spread the data. The chip rate divided by the code length, also called spreading factor, gives the symbol rate. The symbol rate, however, does not correspond to the user data rate. Since the air-interface is prone to errors due to the attenuation of the modulated signal during its propagation through the air and through obstacles, as well as due to interference from other signals, the sender adds redundant data, also called error correcting coding or channel coding, to the transmitted bit stream. The channel code allows the receiver to detect and correct a limited number of transmission errors.

The MAC sub layer generates a sequence of data, called transport block, in periodic intervals that correspond to the radio frame length or to a multiple of it. The physical layer fills the radio frames with the data received from the MAC layer plus some additional information for error detection. It may also be possible to send several transport blocks via the same transport channel within one radio frame in

parallel. A set of simultaneous transport blocks is called transport block set. The transmission time interval (TTI) is defined as the inter-arrival time of transport block sets, which is a multiple of the radio frame duration. The number of bits in the transport channel, i.e., the size and the number of transport blocks, and hence the data rate, can vary with every TTI. However, the radio frames must always be completely filled. This may be accomplished by either

repeating or omitting bits. This is sometimes called rate matching . In order to allow the communication with other mobile and non-mobile stations outside the coverage of the radio base station, the radio base station is typically connected to a communications network in such a way, that user data and control data can be exchanged with the network. Typically, several radio base stations exchange data with a radio network controller (RNC) over an interface that is called Iub in W-CDMA.

Typically, adjacent RNCs can also exchange control

information and data with each other over an interface called Iur. This may be particularly useful when a mobile station moves from one radio cell to another radio cell maintaining a radio connection in both cells, and both cells are not under the control of the same RNC. In this case, one of the

concerned RNCs, called the serving RNC (SRNC) , combines the data received from the Node B controlled by another RNC, called drift RNC (DRNC) , via that other RNCs Iur interface with the data received from the Node B that is under its own control .

The original W-CDMA standard was further enhanced with the aim to allow for higher data transfer speeds. High Speed Downlink Packet Access (HSDPA) is a combination of several techniques that all contribute to enhanced capabilities of the downlink channel. The high speed downlink shared channel (HS-DSCH) is shared between users by means of channel quality dependent scheduling. The users continually transmit

indications of the downlink signal quality. Using this information from all mobile stations, the radio base station decides which user will be sent data on the next radio frame and how much data should be sent for each user. More data can be sent to users which report high downlink signal quality.

Traditionally, in wireless communication, a good radio environment is one with no obstacles between the radio transmitter and the radio receiver. Without reflections and diffractions in the signal path the received signal-to- interference ratio is usually higher than in multipath environments, where the various component signals interfere with each other. However, in urban areas with high rising buildings such a line-of-sight situation is seldom the case and multipath conditions are normality. Fortunately, more advanced wireless systems can even benefit from multipath. If the receiver antenna is able to receive each component signal separately, then they can be combined by the receiving station into one stronger signal, because the received component signals fade independently. These well-known RAKE receivers receive signals that are all copies of each other. On the other hand, multipath can also be used to carry different data signals on each path. In an ideal multipath environment with N transmit antennas and N receive antennas, it is theoretically possible to increase the channel

throughput N fold. This requires very sophisticated signal processing units at the receiver end in order to separate individual component signals. Also, the signal-to- interference ratio must be high enough in order to discern the individual component signals. In situations where the signal-to-interference ratio is not high enough, e.g., at the cell edge, the multiple receive antennas can be used for receive diversity with a single stream of data, as described above.

Current HSDPA specifications support the transmission of two streams from two transmit antennas at the radio base station to two receive antennas at the mobile station, and uses a closed loop feedback from the mobile station to the radio base station to adjust the transmit antenna weighting. Each stream is subject to the same physical layer processing in terms of coding, spreading and modulation as in the

corresponding single stream HSDPA case. Linear pre-coding is used before the modulated signals are mapped to the transmit antennas. To support the transmission of two data streams, the high speed downlink shared channel (HS-DSCH) is modified such that it can transmit two transport blocks per transmission time interval (TTI) instead of only one. Each transport block represents one data stream, and is

individually coded. The processing on the physical layer is identical to the single stream case. The same set of

channelization codes are used for the two streams, in order to avoid wasting channelization code resources.

Under bad radio channel conditions it might be more favorable to fall back to single stream transmission in order to get the benefits from transmit diversity. The adaptation between single stream and dual stream may be based on the feedback from the mobile station. There may also be mobile stations that do not support dual stream MIMO at all, e.g., because of a missing second receive antenna. Single stream MIMO requires that the radio base station supports the scheduling of single transport blocks on HS-DSCH. Single stream MIMO in HSDPA is similar to closed-loop transmit diversity mode-1 in UMTS. It can also be seen as a simple form of beamforming. HSDPA allows a peak data rate of 21 Mbit/s on a single 5 MHz carrier. By aggregating two adjacent carriers, the peak data rate can be doubled. This form of HSDPA transmission is called dual-carrier HSDPA (DC-HSDPA) , or sometimes also dual- cell HSDPA, because the two carrier frequencies represent two overlapping cells. One cell is called primary serving cell, the other one is called secondary serving cell. Either cell can be configured to function as the primary serving cell for a particular DC-HSDPA user, who can be scheduled in the primary serving cell as well as in the secondary serving cell over two parallel high speed downlink shared transport channels (HS-DSCH) . All channels not related to HSDPA reside in the primary serving cell. As with MIMO, the two transport channels used for DC-HSDPA perform hybrid automatic repeat request (HARQ) retransmissions as well as coding and

modulation independently. Unlike MIMO, however, a different number of channelization codes can be used to transmit the two transport blocks. DC-HSDPA can be seen as an alternative to MIMO without the cost and complexity of multi-antennas deployment. However, DC-HSDPA and MIMO can also be combined to achieve even higher data rates. This possibility was recently included in 3GPP specifications. The principle idea of DC-HSDPA can be extended to several adjacent carriers. The achievable data rates scale with the number of aggregated 5 MHz carriers, i.e., assuming N

carriers, the N fold increase of system bandwidth results in an N fold higher peak data rate. Typically, most countries have three or four operators at the 2100 MHz band, which has a range of 60 MHz. Therefore, 15 or 20 MHz are available per operator, so in practice three or four adjacent 5 MHz carriers would be available for aggregation. With carrier aggregation not only the peak data rate

increases, but also the overall system capacity improves because of the possibility to balance the traffic load between the different carriers. Therefore, three- and four- carrier HSDPA is currently introduced into 3GPP

specifications.

A prerequisite for the deployment of Dual- and Multi-Carrier HSDPA is the availability of sufficient spectrum. Not all mobile operators have access to more than 5 or 10 MHz of spectrum in a single frequency band, but often additional spectrum is available in other frequency bands. Dual-band HSDPA was recently introduced in 3GPP specifications. Dual- band HSDPA combines two or more 5 MHz carriers from two different frequency bands for joint transmission. Dual-band HSDPA is thus not an alternative to Dual-cell HSDPA but rather a further development variant without the requirement for adjacent carriers. Dual-band HSDPA is easy to implement in a network that already deploys those two frequency bands. It is more of a challenge for the mobile station. A mobile station typically supports at least two HSDPA frequencies but those two frequencies are not used at the same time. In the case of dual-band HSDPA, the mobile station must receive on two frequencies at the same time, which increases the RF complexity as receivers on both bands must be able to operate simultaneously and regardless of which band the mobile station is transmitting in the uplink to the radio base station. The scheduling in the radio base station between the two bands can be done dynamically based on channel quality indicator reports received from the mobile terminal. In current 3GPP specifications, dual-band HSDPA is defined for downlink transmission only. The uplink transmission uses one frequency band only, and the network selects which of the two bands is used for uplink transmission. As the lower frequency band has better propagation, the radio coverage areas of the different bands are different in size, which may require inter-frequency handovers for the uplink if the mobile station moves out of the coverage area of the higher

frequency carrier.

The interface between the radio network controller (RNC) and the radio base station is called Iub in W-CDMA. This

interface allows the RNC to control and manage the radio base station by sending and receiving control information to and from the radio base station according to a communications protocol. The protocol can be divided into layers, the transport network layer and the radio network layer. The part of the protocol that defines the control messages sent between RNC and radio base station is called Node B

application part (NBAP) . The NBAP is defined in terms of control messages exchanged between the controlling RNC and the Node B. For example, the controlling RNC can request state and configuration information about a particular cell sending an Audit Request message to the corresponding Node B. The Node B would then return the requested information in an Audit Response message. This message may then contain an information element called Cell Capability Container that indicates to the controlling RNC specific capabilities of the cell. It is important for the correct and efficient

functioning of the communication network, that the

controlling RNC has the most up-to-date information about the cell capabilities. Therefore, the Node B may also send by its own a message to its controlling RNC, e.g., a Resource Status Indication, containing the same information element, when a new cell was installed and configured, or when the

capabilities of a cell were changed. The Cell Capability Container is a sequence of bits and may also comprise spare bits for future use. These spare bits are set to zero by the sender and are ignored by the receiver.

The interface between a serving RNC (SRNC) and a drift RNC (DRNC) is called Iur in W-CDMA. With respect to a specific mobile station only one RNC, the SRNC, exchanges data and control information with the network. Therefore, a logical interface is needed between the SRNC and the DRNC, called Iur, in order to transfer data and control information. The Iur interface allows the SRNC manage connections with mobile station that are under the coverage of radio cells controlled by the DRNC. The communications protocol on this interface can again be divided into layers, the transport network layer and the radio network layer. The part of the protocol that defines the control messages sent between RNCs is called

Radio Network Subsystem Application Part (RNSAP) . The RNSAP defines procedures that exchange messages between two RNCs. For example, if an additional radio link is to be established between a mobile station and a radio base under the control of a DRNC, the SRNC may send a Radio Link Addition Request message to the DRNC in order to allocate the necessary resources for the additional radio link. The DRNC may then reply with a Radio Link Addition Response message indicating the cell capabilities to the SRNC.

In a communications network, there is a need of requiring the full and correct information of the full capabilities of each individual network node in order to ensure the correct and efficient functioning of the communication network, as the lack of the fully updated information results in an

inefficient usage of overall network resources. However, currently there is no solution available for

signaling the full cell capabilities with regard to the above discussed options of transmission techniques. Thus, there is still a need for an improved method for transmitting data in a radio communications network.

SUMMARY OF THE INVENTION Object of the present invention is improving of data

transmission in a radio communications system.

This object is achieved by methods comprising features according to claims 1, 3, and 7, a radio base station

comprising features according to claim 2, and network nodes comprising features according to claims 5 and 8.

Further embodiments of the present invention are provided with the corresponding dependent claims.

The object of the present invention is achieved by a method for transmitting data in a radio communications system, the method comprising transmitting, from a radio base station, the radio base station spanning a cell, to a network node, cell capability information, wherein the cell capability information comprises

- a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The method allows for a correct and efficient functioning of the communication network, as the network node has the most up-to-date information about the cell capabilities of the cell spanned by the radio base station.

The object of the present invention is also achieved by a radio base station configured for transmitting data in a radio communications system, the radio base station

comprising cell spanning means configured for spanning a cell;

the radio base station further comprising transmitting means configured for transmitting, to a network node, cell

capability information, wherein the cell capability

information comprises

- a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed; - a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The radio base station allows for a correct and efficient functioning of the communication network, as the network node has the most up-to-date information about the cell

capabilities of the cell spanned by the radio base station.

The object of the present invention is also achieved by a method for receiving data in a radio communications system, the method comprising receiving, by a network node from a radio base station, the radio base station spanning a cell, cell capability information, wherein the cell capability information comprises

- a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The method allows for a correct and efficient functioning of the communication network, as the network node has the most up-to-date information about the cell capabilities of the cell spanned by the radio base station.

According to embodiments of the present invention, the method further comprises forwarding the received cell capability information to a further network node.

The method allows for a correct and efficient functioning of the communication network, as also the further network node has the most up-to-date information about the cell

capabilities of the cell spanned by the radio base station.

The object of the present invention is also achieved by a network node configured for transmitting and receiving data in a radio communications system, the network node comprising receiving means configured for receiving, from a radio base station, the radio base station spanning a cell, cell

capability information, wherein the cell capability

information comprises

- a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed; - a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The network node allows for a correct and efficient

functioning of the communication network, as the network node has the most up-to-date information about the cell

capabilities of the cell spanned by the radio base station.

According to embodiments of the present invention, the network node further comprises forwarding means configured for forwarding the received cell capability information to a further network node.

The method allows for a correct and efficient functioning of the communication network, as also the further network node has the most up-to-date information about the cell

capabilities of the cell spanned by the radio base station.

The object of the present invention is also achieved by a method for receiving data in a radio communications system, the method comprising receiving, by a network node from a further network node, cell capability information, wherein the cell capability information comprises

- a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The method allows for a correct and efficient functioning of the communication network, as the network node has the most up-to-date information about the cell capabilities.

The object of the present invention is also achieved by a network node configured for receiving data in a radio

communications system, the network node comprising receiving means configured for receiving, from a further network node, cell capability information, wherein the cell capability information comprises

- a first cell capability information indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information indicating a second transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The network node allows for a correct and efficient

functioning of the communication network, as the network node has the most up-to-date information about the cell

capabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood from the following description of the preferred embodiments of the invention read in conjunction with the attached drawings, in which :

Fig. 1 shows an implementation of the present invention according to some embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 shows an implementation of the present invention according to some embodiments of the present invention.

In particular, Fig. 1 shows methods and devices for

transmitting data in a radio communications network. The radio communications network comprises a radio base station 12, a network node 13, and a further network node 16.

According to some embodiments of the invention, the network nodes 13, 16 are Radio Network Controllers (RNCs) , and the radio base station 12 is a Node B.

For MIMO operation with MC-HSDPA, it has been agreed in 3GPP that the Node B needs to provide its local cell capability in a message NBAP : Audit Response and Resource Status Indication to the network, and in particular to its controlling RNC.

MIMO related cell capability is reported in the Cell

Capability Container Information Element (IE) as follows:

DC-HSDPA over Single Band and MIMO (without Single Stream restriction)

DC-HSDPA over Single Band and MIMO with Single Stream restriction

DC-HSDPA over Dual Band and MIMO (without Single Stream restriction)

HSDPA multiple Carrier, especially 3 or 4 Carrier, over Single Band and MIMO (without Single Stream restriction)

HSDPA 3 or 4 Carrier over Dual Band and MIMO (without Single Stream restriction)

MIMO with Single Stream Restriction was introduced to consider some UE limitation (e.g. resource limited UE like single Rx, limited memory etc.) when operating in MIMO mode. The RNC could know this type of UE from UE's capability.

Therefore, the configuration for Multi-Carrier HSDPA and MIMO with single stream restriction is feasible and practical for certain type of UEs. However, there is no cell capability information related to Multi Carrier HSDPA (especially 3 carriers or 4 carriers, or 8 carriers) HSDPA with Single Stream MIMO operation in current 3GPP specifications. As already indicated above, the lack of the capability information potentially generates, amongst others, the following problems/risk from 3GPP specification point of view :

Since the RNC does not know the cell's capability, the RNC may request to execute MC-HSDPA with Single

Stream MIMO to a cell which does not implement the feature. This would generate unsuccessful attempts, and therefore would waste resources. The MC-HSDPA and MIMO with Single Stream restriction may be considered to be dependent on MC-HSDPA capability and Rel9: Single Stream MIMO capability, i.e. the specification mandates the cell, which supports Single Stream MIMO and MC-HSDPA, to support simultaneously MC-HSDPA and Single Stream MIMO. This reduces flexibility of implementation.

According to the invention, and as shown in Fig. 1, the Node B provides the cell's capability for simultaneous

configuration of MC-HSDPA and MIMO with Single Stream

restriction independently from Multi Cell capability info and Single Stream capability info. Hence, tight feature

dependency and inflexibility in the implementation of the features can be avoided.

From the perspective of the radio base station 12, Fig. 1 shows a method 1 for transmitting data in a radio

communications system, the method 1 comprising transmitting 11, from the radio base station 12, the radio base station spanning a cell, to a network node 13, cell capability information 14. The network node 13 can be an RNC, in

particular the controlling RNC for the radio base station 12, or Node B, spanning the cell.

The cell capability information 14 comprises

- a first cell capability information 141 indicating a first transmission capability of the cell regarding transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability 142 information indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability 143 information indicating a third transmission capability of the cell regarding transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed.

The radio base station 12 is therefore configured for

transmitting data in a radio communications system and comprises cell spanning means configured for spanning a cell. Furthermore, the radio base station 12 comprises transmitting means 121 configured for transmitting 11, to the network node 13, which can be the controlling RNC for the radio base station 12, the cell capability information 14 which

comprises the above described first, second and third cell capability information 141, 142, 143.

From the perspective of the network node 13, or controlling RNC, the method 1 comprises receiving 11, from the radio base station 12, or Node B, the cell capability information which comprises the above described first, second and third cell capability information 141, 142, 143.

According to some embodiments of the invention, the method 1 further comprises forwarding 15 the received cell capability information 14 to a further network node 16. The further network node can be another RNC.

According to some embodiments of the invention, the cell capability information 14 is comprised in an Information Element (IE) which is called Capability Extension IE. The Capability Extension IE is contained in Uplink Signalling

Transfer indication and in Neighbouring Cell Information in RL Setup/Addition Response. In case of the radio base station 12, or Node B, transmitting this IE to the CRNC 13, the Node B 12 reports the IE to the CRNC 13 over the Iub interface. In case of the DRNC 13 forwarding the cell capability information 14 to the SRNC 16, the DRNC 13 reports the IE to SRNC 16 over the Iur interface.

The DRNC 13 may also forward messages received via a Node B 12 from the mobile station to the SRNC using the Uplink Signaling Transfer Indication including the cell

capabilities .

As an advantage of the invention, as the SRNC 16 decides to execute "Dual Band and Single Stream MIMO Capability/Dual Band", "HSDPA 3 or 4 Carrier and Single Stream MIMO

Capability/Adj acent-carrier", or "HSDPA 3 or 4 Carrier and Single Stream MIMO Capability/Dual Band" based on the

received IEs, the SRNC 16 does not request to execute the feature for a cell which is not capable of the feature, thereby preventing unsuccessful attempts of requesting a service not being supported by the cell.

The network node 13, or RNC, receiving the cell capability information 14 from the radio base station 12, or Node, comprises receiving means 131 configured for receiving 11, from the radio base station 12, the cell capability

information 14 which comprises the above described first, second and third cell capability information 141, 142, 143.

According to some embodiments of the invention, the network node 13, or RNC, further comprises forwarding means 132 configured for forwarding 15 the received cell capability information 14 to a further network node 16. This covers the situation where the DRNC 13 forwards the cell capability information 14 to the SRNC 16 over the Iur interface. From the perspective of the SRNC 16, the method 1 comprises receiving 15, from the DRNC 13, the cell capability

information 14 which comprises the above described first, second and third cell capability information 141, 142, 143.

The SRNC 16 comprises receiving means 161 configured for receiving 15, from the DRNC 13, the cell capability

information 14 which comprises the above described first, second and third cell capability information 141, 142, 143.

According to the invention, the proposed capability IEs are included in the Cell Capability Container IE in NBAP : Audit Response/Resource Status Indication and Cell Capability

Container Extension IE in RNSAP messages.

For NBAP, the proposed IEs can be implemented as shown in the below table 1. In particular, the proposed cell capability information 14 is signalled using the bits xxl5, xxl6, and xxl7. It has to be noted that the exact position of the bits used for signalling the cell capability information 14 as proposed, i.e. as fifteenth, sixteenth, and seventeenth bit, is not critical, and that other positions for signalling the proposed cell capability information 14 are possible within the Cell Capability Container.

IE/Group Name Presen Range IE Type Semantics

ce and Description

Referen

ce

Cell Capability BIT Each bit

Container STRING indicates

(128) whether a cell supports a particular functionality or not. The value 1 of a bit

indicates that the

corresponding functionality is supported in a cell and value 0 indicates that the

corresponding functionality is not supported in a cell. Each bit is defined as follows .

Bit xxl: Cell Specific Tx Diversity

Handling For Multi Cell

Operation

Capability

/Multi-cell/ . Bit xx2 : Multi Cell and MIMO Capability/Adj ac ent-carrier/ . Bit xx3: Multi Cell and Single Stream MIMO Capability/Adj ac ent-carrier/ . Bit xx4: Multi Cell E-DCH

Capability/Adj ac ent-carrier/ . This bit shall be ignored by the CRNC if bit xx5 : Separate Iub Transport Bearer

Capability = "0" and bit xx6: E- DCH UL Flow Multiplexing Capability = "0" Bit xx5 :

Separate Iub Transport Bearer Capability/Adj ac ent-carrier/ . This bit shall be ignored by the CRNC if bit xx4: Multi Cell E-DCH Capability = "0"

Bit xx6: E-DCH UL Flow

Multiplexing Capability/Adj ac ent-carrier/ . This bit shall be ignored by the CRNC if the bit xx4: Multi Cell E-DCH

Capability = "0" Bits xx7 to xxll Maximum No of HSDPA

Frequencies capability/Multi

-cell/.

This capability is coded as the binary representation of the maximum number of HSDPA frequencies , with bit xx7 as the MSB and bit xxll as the LSB. Hexadecimal digit 0 means no support for 4C- HSDPA.

Hexadecimal digits 1 and 2 are reserved. Bit xxl2 : Dual Band and MIMO Capability/Dual Band/ .

Bit xxl3: HSDPA 3 or 4 Carrier (or 8 Carrier) and MIMO Single Band

Capability/Adj ac ent-carrier/ Bit xxl4: HSDPA 3 or 4 Carrier (or 8 Carrier) and MIMO Dual Band

Capability/Dual Band/ .

Bit xxl5: Dual band and Single Stream MIMO Capability/Dual Band/ .

Bit xxl6: HSDPA 3 or 4 Carrier (or 8 Carrier) and Single

Stream MIMO

Capability/Adj ac ent-Carrier/ .

Bit xxl7: HSDPA

3 or 4 Carrier (or 8 Carrier) and Single

Stream MIMO

Capability/Dual

Band/ .

Note that undefined bits are considered as a spare bit and spare bits shall be set to 0 by the

transmitter and shall be ignored by the receiver. Note that

Reserved bits are not

considered as a spare bit. They shall however be set to 0 by the transmitter and shall be ignored by the receiver.

- Table 1 - For RNSAP, the proposed IEs can be implemented as shown in the below table 2. In particular, the proposed cell

capability information 14 is signalled using the bits xxl5, xxl6, and xxl7. It has to be noted that the exact position of the bits used for signalling the cell capability information 14 as proposed, i.e. as fifteenth, sixteenth, and seventeenth bit, is not critical, and that other positions for signalling the proposed cell capability information 14 are possible within the Cell Capability Container.

IE/Group Name Presen Range IE Type Semantics

ce and Description

Referen

ce

Cell Capability BIT Each bit

Container STRING indicates

Extension FDD (128) whether a cell supports a particular functionality or not. The value 1 of a bit

indicates that the

corresponding functionality is supported in a cell and value 0 indicates that the

corresponding functionality is not supported in a cell. Each bit is defined as follows .

Bit xxl: Cell

Specific Tx Diversity

Handling For Multi Cell Operation

Support

Indicator, /Multi-cell/ . Bit xx2 : Multi Cell and MIMO Support

Indicator, /Adj acent- carrier/ .

Bit xx3: Multi Cell and Single Stream MIMO Support

Indicator, /Adj acent- carrier/ .

Bit xx4: Multi Cell E-DCH Support

Indicator, /Adj acent- carrier/ .

This bit shall be ignored by the SRNC if bit xx5 : Separate Iur Transport Bearer Support Indicator = "0" and bit xx6: E- DCH UL Flow Multiplexing Support

Indicator = "0" Bit xx5 :

Separate Iur Transport Bearer Support

Indicator,

/Adj acent- carrier/ .

This bit shall be ignored by the SRNC if bit xx4: Multi Cell E-DCH Support Indicator = "0" Bit xx6: E-DCH UL Flow

Multiplexing Support

Indicator,

/Adj acent- carrier/ .

This bit shall be ignored by the SRNC if bit xx4: Multi Cell E-DCH Support Indicator = "0" Bit xx7 to xxl 1 : Maximum No of HSDPA

Frequencies Support

Indicator,

/Multi-cell/ . This support indicator is coded as the binary

representation of the maximum number of HSDPA frequencies , with bit xx7 as the MSB and bit xxll as the LSB. Hexadecimal digit 0 means no support for 4C- HSDPA.

Hexadecimal digits 1 and 2 are reserved. Bit xxl2 : Dual Band and MIMO Support

Indicator, /Dual Band/ .

Bit xxl3: HSDPA 3 or 4 Carrier

(or 8 Carrier) and MIMO Single Band Support Indicator,

/Adj acent- carrier/

Bit xxl4: HSDPA 3 or 4 Carrier

(or 8 Carrier) and MIMO Dual Band Support Indicator, /Dual Band/ .

Bit xxl5: Dual band and Single Stream MIMO Capability/Dual Band/ . Bit xxl6: HSDPA 3 or 4 Carrier

(or 8 Carrier) and Single

Stream MIMO Capability/Adj ac ent-Carrier/ . Bit xxl7: HSDPA 3 or 4 Carrier

(or 8 Carrier) and Single

Stream MIMO Capability/Dual Band/ .

Note that undefined bits are considered as a spare bit and spare bits shall be set to 0 by the

transmitter and shall be ignored by the receiver. Note that

Reserved bits are not

considered as a spare bit. They shall however be set to 0 by the transmitter and shall be ignored by the receiver.

- Table 2 - While embodiments and applications of this invention have been shown and described above, it should be apparent to those skilled in the art, that many more modifications (than mentioned above) are possible without departing from the inventive concept described herein. The invention, therefore, is not restricted except in the spirit of the appending claims. Therefore, it is intended that the foregoing detailed description should be regarded as illustrative rather than limiting .

LIST OF ABBREVIATIONS:

CRNC Control-RNC

DC-HSDPA Dual Carrier-HSDPA

IE Information Element

HSDPA High Speed Downlink Packet Access

MIMO Multiple Input Multiple Output

NBAP Node B Application Protocol

RNSAP Radio Network Subsystem Application

RNC Radio Network Controller

SRNC Serving-RNC

WI Work Item

LIST OF REFERENCES:

1 method for transmitting data

11 transmitting, receiving

12 radio base station

121 transmitting means

13 network node

131 receiving means

132 forwarding means

14 cell capability information

141 first cell capability information

142 second cell capability information

143 third cell capability information

15 forwarding, receiving

16 network node

161 receiving means

Claims

1. Method (1) for transmitting data in a radio communications system, the method (1) comprising transmitting (11), from a radio base station (12), the radio base station spanning a cell, to a network node (13), cell capability information (14), wherein the cell capability information (14) comprises

- a first cell capability information (141) indicating a first transmission capability of the cell regarding

transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability (142) information indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further

indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability (143) information indicating a third transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

2. Radio base station (12) configured for transmitting data in a radio communications system, the radio base station (12) comprising cell spanning means configured for spanning a cell ;

the radio base station (12) further comprising transmitting means (121) configured for transmitting (11), to a network node (13), cell capability information (14), wherein the cell capability information (14) comprises - a first cell capability information (141) indicating a first transmission capability of the cell regarding

transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information (142) indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further

indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information (143) indicating a third transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

3. Method (1) for receiving data in a radio communications system, the method (1) comprising receiving (11), by a network node (13) from a radio base station (12), the radio base station (12) spanning a cell, cell capability

information (14), wherein the cell capability information comprises

- a first cell capability information (141) indicating a first transmission capability of the cell regarding

transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information (142) indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further

indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information (143) indicating a third transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

4. Method (1) according to claim 3, wherein the method (1) further comprises

forwarding (15) the received cell capability information (14) to a further network node (16) .

5. Network node (13) configured for transmitting and

receiving data in a radio communications system, the network node (13) comprising receiving means (131) configured for receiving (11), from a radio base station (12), the radio base station (12) spanning a cell, cell capability

information (14), wherein the cell capability information (14) comprises

- a first cell capability information (141) indicating a first transmission capability of the cell regarding

transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information (142) indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further

indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed; - a third cell capability information (143) indicating a third transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

6. Network node (13) according to claim 5, the network node (13) further comprising forwarding means (132) configured for forwarding (15) the received cell capability information (14) to a further network node (16) .

7. Method (1) for receiving data in a radio communications system, the method (1) comprising receiving (15), by a network node (16) from a further network node (13), cell capability information (14), wherein the cell capability information comprises

- a first cell capability information (141) indicating a first transmission capability of the cell regarding

transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information (142) indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further

indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information (143) indicating a third transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.

8. Network node (16) configured for receiving data in a radio communications system, the network node (16) comprising receiving means (161) configured for receiving (15), from a further network node (13), cell capability information (14), wherein the cell capability information (14) comprises

- a first cell capability information (141) indicating a first transmission capability of the cell regarding

transmissions over dual carrier frequencies, the dual carrier frequencies being comprised in two frequency bands, the first cell capability information further indicating if a

restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a second cell capability information (142) indicating a second transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in a single frequency band, the second cell capability information further

indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed;

- a third cell capability information (143) indicating a third transmission capability of the cell regarding

transmissions over multiple carrier frequencies, the multiple carrier frequencies being comprised in two frequency bands, the third cell capability information further indicating if a restriction of the transmissions to a single stream MIMO transmission mode is allowed.