WO2011020735A2

WO2011020735A2 - A method of transmitting a signal from a mobile station to a network entity in a communications network

Info

Publication number: WO2011020735A2
Application number: PCT/EP2010/061563
Authority: WO
Inventors: Klaus Knoche; Hans Dieterich; Joachim Schmid; Markus Reinhardt; Thomas Chapman
Original assignee: Nokia Siemens Networks Oy
Priority date: 2009-08-18
Filing date: 2010-08-09
Publication date: 2011-02-24
Also published as: WO2011020735A3

Abstract

A method of transmitting a signal from a mobile station to a network entity in a communications network, wherein the network has a first operating mode using a general control channel (DPCCH), a packet data associated control channel (E- DPCCH)and a packet data channel (E-DPDCH), in which a first transmission and hybrid ARQ retransmissions from the mobile station to the network entity are made on the packet data channel (E-DPDCH) and signalling for the hybrid ARQ retransmissions are transmitted on the packet data associated control channel (E-DPCCH), and a second operating mode, wherein in the second operating mode the packet data associated control channel(E-DPCCH) is prevented from being transmitted during at least part of a time allocated for data transmissions and the format of the transmission and/or the number of retransmissions is predetermined or signalled between the network entity and the mobile station.

Description

A METHOD OF TRANSMITTING A SIGNAL FROM A MOBILE STATION TO A NETWORK ENTITY IN A COMMUNICATIONS NETWORK

FIELD OF THE INVENTION

The invention generally relates to a method of transmitting a signal from a mobile station to a network entity in a commu^¬ nications network. More particularly, the invention relates to high speed uplink packet access (HSUPA) transmission in a radio communications network using WCDMA according to the 3GPP standard.

BACKGROUND OF THE INVENTION

During uplink transmission from a mobile station to a base station in radio networks employing WCDMA (high speed uplink packet access (HSUPA) ) , the support of larger cell ranges is limited. When a mobile station (UE) is a longer distance from a base station (BTS or NodeB) in the network, for example on the edge of a cell, the UE will encounter power limitations. Compared to legacy transport or dedicated channel (DCH) transmission, HSUPA transmission shows an inferior per- formance in such a situation regarding coverage, particularly when a 2 ms transmission time interval (TTI) length is configured.

In HSUPA, transmission take place using two control channels and one data channel using either a 2 ms or a 10 ms TTI. The data channel (enhanced dedicated physical data channel (E- DPDCH) ) carries user data in the uplink direction, the first control channel is a general control channel (dedicated physical control channel (DPCCH) ) and the second control channel (enhanced dedicated physical control channel (E- DPCCH) ) is a packet data associated control channel and carries E-DPDCH data-related rate information, retransmission information and information used by the base station for scheduling control. In particular, the E-DPCCH carries the E-TFC (enhanced transport format combination) index, the so- called "happy bit" (which is a bit of information on whether the mobile station could increase the data rate or not) and the retransmission sequence number (RSN) , which contains m- formation about whether and how many times data is retransmitted.

One of the reasons for HSUPA transmission degradation relative to DCH transmission is that additional power is required to be used by the UE for the further physical control channels as well as the data channels. This situation is illus^¬ trated in Figure 1, which shows the transmit power of a mobile station as a function of time and illustrates uplink transmission of control and data channels during a TTI. Dur- ing one TTI it is in any case required to transmit the gen^¬ eral control channel (DPCCH) . In HSUPA there is in addition the control channel associated with the data channel (E- DPCCH) , which is mandatory in HSUPA, as well as the data channel (E-DPDCH) . The UE has thus already almost reached its maximum power level by transmitting the control channels DPCCH and E-DPCCH when it is at the edge of a cell and does not have enough power left to transmit the data channel E- DPDCH. This is one of the reasons that the UE may not be able to maintain even minimum data rates when it is near the edge of a large cell and far away from a base station in HSUPA transmission, whereas in DCH transmission would still allow reduced data rates in the same situation. SUMMARY OF THE INVENTION

Accordingly, the invention provides a method of transmitting a signal from a mobile station to a network entity in a communications network. The network has a first operating mode and the first operating mode uses a general control channel (DPCCH), a packet data associated control channel (E- DPCCH) and a packet data channel (E-DPDCH) . In the first operating mode, a first transmission and hybrid ARQ retransmis^¬ sions are made on the packet data channel (E-DPDCH) and signalling for the hybrid ARQ retransmissions is transmitted on the packet data associated control channel (E-DPCCH) . The network also has a second operating mode. In the second op^¬ erating mode, the packet data associated control channel (E- DPCCH) is prevented from being transmitted during at least part of a time allocated for data transmissions and the format of the transmission and/or the number of retransmissions is predetermined or signalled between the network entity and the mobile station. The E-DPCCH is either modified or prevented from being transmitted alto^¬ gether in the second operating mode. Modification of the E- DPCCH can include only transmitting the E-DPCCH for some of the TTIs normally used for transmission of data packets or time multiplexing the E-DPCCH with the E-DPDCH.

In this way, the transmit power of the mobile station is not completely used up by transmitting the control channels and therefore transmission of data using HSUPA is permitted at a larger distance of the mobile station from the base station (NodeB) . Preferably, the mobile station comprises means to trans^¬ mit automatic retransmissions on the packet data channel (E- DPDCH) without acknowledgement feedback from the network entity in the second operating mode. The mobile station may comprise means to transmit the packet data associated control channel (E-DPCCH) containing at least one of an indication of a transport format and a number of automatic retransmissions in the second operating mode. The mobile station may also include means for signalling the format of the first transmission and automatic retransmissions in the second operating mode to the network entity in the packet data associated control channel (E-DPCCH) . The contents of the packet data associated control channel (E- DPCCH) can be modified compared to the first operating mode. The mobile station may also have means for transmitting sig^¬ nalling related to the first transmission and automatic retransmissions, to the network entity m the second operating mode in a control channel associated with the packet data channel (E-DPCCH) that is time multiplexed with the packet data channel (E-DPDCH) . This provides the advantage that no RSN is required and also that ACK/NACK signalling via E-HICH is only required at the end of the repetition sequence in the downlink direction, or even that no HARQ component is re- quired at all, which avoids E-HICH completely.

Advantageously, the mobile station may further include means for signalling, in the second operating mode, packet data related signalling comprising at least one of the transport format of the first transmission or a number of automatic retransmissions or a retransmission sequence number to the network entity. The mobile station can further include means for transmitting the packet data related signalling, in the second operating mode, to the network entity in signalling bits of the general control channel (DPCCH) . Furthermore, the contents of the general control channel (DPCCH) can be modified compared to the first operating mode. Since the general control channel is required anyway, using the DPCCH to transmit the packet data related signalling means that no modification is re^¬ quired and power is not used for sending bits on the packet data related control channel. This leads to an even more significant amount of power saving in the mobile station (UE) and therefore more power is available for sending data, for example . The network entity may include means for signalling, in the second operating mode, to the mobile station at least one of the information of the available data format, a timing of the first transmission and a number of automatic retransmissions .

In one embodiment of the invention, the network entity comprises means for switching the mobile station between the first and second operation modes. In another embodiment of the invention, the mobile station comprises means for autonomously selecting the first or the secondary operating mode.

Preferably, the network entity comprises means for signalling a modified set of transmission configuration parameters to the mobile station for use in the second operating mode.

The invention further provides a mobile station. The mobile station includes a transmitter, a receiver, and a transmis- sion controller and is configured to operate in a first oper^¬ ating mode and a second operating mode. In the first operating mode, the transmitter is adapted to transmit a general control channel (DPCCH) . The transmitter is also adapted to transmit a first transmission and hybrid ARQ retransmis^¬ sions from the mobile station to a network on a packet data channel (E-DPDCH) , and to transmit signalling for the packet data and for the hybrid ARQ retransmissions on a packet data associated control channel (E-DPCCH) in the first oper- ating mode. Furthermore, the mobile station is configured to operate in a second operating mode. In the second operating mode, the transmission controller is further configured to prevent the packet data associated control channel (E-DPCCH) from being transmitted during at least part of a time allo- cated for data transmissions. The mobile station is also configured in the second operating mode to use a number of retransmissions and/or transmission format that is received at the receiver, predetermined or determined by the mobile station.

The invention also provides a network entity configured to operate in a first operating mode using a general control channel (DPCCH) , a packet data associated control channel (E- DPCCH) and a packet data channel (E-DPDCH) . The network en- tity includes a receiver for receiving a first transmission and hybrid ARQ retransmissions from a mobile station on the packet data channel (E-DPDCH) and for receiving signalling for the hybrid ARQ retransmissions on the packet data associated control channel (E-DPCCH) . The network en- tity is further configured to operate in a second operating mode in which the receiver does not receive the packet data associated control channel (E-DPCCH) during at least part of a time allocated for data transmissions. The network entity also has resource control means for signalling the format of the transmission and/or the number of retransmissions to the mobile station during the second mode of operation.

Preferably, the network entity comprises means for detecting the presence of the control channel carrying signalling associated with the packet data channel. The network entity can detect that signalling related to packet data is being trans- mitted in bits on the general control channel and thus that the second mode of operation is in use.

The invention will now be described, by way of example only, with reference to specific embodiments, and to the accompany- ing drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph of the transmit power of a mobile station as a function of time for a conventional method of transmitting a signal from a mobile station to a network entity in a communications network;

Figure 2 is a simplified schematic diagram of a communications network; - Figure 3 is a simplified schematic diagram of a mobile station according to an embodiment of the invention; Figure 4 is a simplified schematic diagram of a network entity according to an embodiment of the invention;

Figure 5 is a graph of the transmit power of a mobile station as a function of time for a method of transmitting a signal from a mobile station to a network en^¬ tity in a communications network according to an embodiment of the invention; - Figure 6 is a graph of the transmit power of a mobile station as a function of time for a method of transmitting a signal from a mobile station to a network entity in a communications network according to an embodi^¬ ment of the invention; and

Figure 7 is a simplified schematic block diagram of transmission of a signal from a mobile station to a network entity according to an embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Figure 2 schematically shows a communications network having a network entity or base station (base transceiver station (BTS) or NodeB) NodeB and a network controller RNC. A mobile station UE is m communication with the network via the base station NodeB. The mobile station UE is shown schematically in Figure 3 and includes a transmitter T, a receiver R, a processor P and a transmission controller TC. The base sta- tion NodeB is illustrated schematically in Figure 4 and includes a receiver RNB and a radio resource controller RRC. The network has two modes of operation. In the first mode of operation, a data channel (E-DPDCH) , a general control channel (DPCCH) and a packet data associated control channel (E- DPCCH) are used according to the current standard. First transmissions and hybrid ARQ retransmissions are made on the E-DPDCH and signalling for the hybrid ARQ retransmissions is transmitted on the E-DPCCH. In the second mode of operation, the E-DPCCH is either not transmitted at all or is modified in some way, e.g., by preventing the E-DPCCH from being transmitted during at least part of the TTI allocated for data transmissions (where the TTI is either 2 ms or 10 ms) or by time multiplexing the E-DPCCH with the E-DPDCH.

If the mobile station UE encounters a power limitation, for example if it is located at the edge of a cell and is therefore a long way from the base station NodeB (and any other base station in the network) , the base station NodeB and the mobile station UE switch from the first to the second mode of operation. Either the mobile station UE switches autono- mously from the first mode to the second mode, and/or the mo^¬ bile station UE is switched from the first mode to the second mode by the network; i.e, by the radio network controller RNC via the base station NodeB or by the base station NodeB autonomously. The mobile station UE is able, via the proces- sor P included therein, to autonomously select the first or the second operating mode. The mobile station UE may at any time choose to select the operating mode of the current stan^¬ dard (a first operating mode) or the modified mode of E- DPCCH/E-DPDCH transmission (a second operating mode) .

The second mode of operation may be implemented using several alternative methods, as described below. In the second mode of operation, the allowed number of data blocks (enhanced transport format combinations (E-TFCs)) to be transmitted per TTI by the mobile station UE compared to the current standard is restricted to one or a set of E-TFCs.

In order to transmit the E-TFC index for the restricted set of E-TFCs, the following alternatives are possible:

The set of available E-TFCs are limited to a single fixed E- TFC and this single fixed E-TFC is signalled via radio resource control (RRC) by the radio network controller RNC via the base station NodeB to the mobile station UE and via an NBAP message to the NodeB at the radio link setup or reconfiguration. Therefore, no E-TFC index is required at all.

Alternatively, the set of available E-TFCs is limited to a subset of currently standardized E-TFCs for low data rates only. The selection of the E-TFC by the mobile station UE is signalled with the help of TFCI bits transmitted in the DPCCH to the base station NodeB by the mobile station UE. Since the DPCCH must be transmitted by the mobile station UE in any case, the transmit power of the mobile station UE is not unnecessarily used for transmitting the E-DPCCH. Figure 5 shows the transmit power P_τx of the mobile station UE as a function of time and shows the transmission of control and data channels during a TTI. It is a schematic il^¬ lustration of uplink transmission according to embodiments of the invention in which E-DPCCH transmission is omitted and either the general control channel DPCCH carries signalling associated with the packet data channel E-DPDCH or this sig^¬ nalling is substituted by predetermined configurations. In one embodiment, a fixed number of repetitions are always used. This fixed number is signalled at the radio link setup or reconfiguration via RRC by the radio network controller RNC to the mobile station UE and via an NBAP message to the base station NodeB . Therefore no retransmission sequence number (RSN) is required at all. In the receiver of the base station NodeB, Chase Combining, or Incremental Redundancy of the repeated data is performed to enhance the coverage range. The additional advantage of this embodiment is that ACK/NACK signalling via E-HICH is only required at the end of the repetition sequence in the downlink direction or no HARQ component is used at all, thereby avoiding E-HICH completely.

In an alternative embodiment, the RSN bits may be signalled with the help of transport format combination indicator (TFCI) bits transmitted in the DPCCH, which are transmitted using DPCCH slot format 0. Two RSN bits are used in combination with incremental redundancy. The RSN bits transmitted in the TFCI bit fields of the DPCCH are repeated in all slots of the TTI.

As an alternative, just one RSN bit may be used in combination with Chase Combining or Incremental Redundancy of the repeated data in the base station NodeB (where RSN = 0 corre- sponds to the initial transmission and RSN = 1 corresponds to retransmission) . Within a TTI the RSN bit is repeated within the TFCI bits of the DPCCH (slot format 0) . (The mobile sta^¬ tion UE transmits the packet) . In a further embodiment, E-TFC signalling is performed for a restricted subset of E-TFCs. In combination with limiting the set of available E-TFCs to a subset of currently standardized E-TFCs for small data rates, the selected E-TFC is signalled to the NodeB, which is done by using the TFCI bits of the DPCCH. The following coding is used:

The single RSN bit described above and 2 E-TFC selection bits are used for the selection of one out of a restricted set of four E-TFCs. A rate 1/10 coding scheme is used, resulting in 30 TFCI bits transmitted within the (for example) 15 slots of a 10 ms TTI. In an additional embodiment, a restricted subset of E-TFCs is used and signalling the selected ETFC takes place as described above using the above coding. However, in this embodiment a fixed number of repetitions are used, therefore no RSN bits are required.

In the above embodiments the base station NodeB is not re^¬ quired to signal a happy bit, since the UE will be "happy"; i.e., not need or not be able to support higher data rates due to its power limitation.

Figure 6 shows the transmit power P_τx of the mobile station UE as a function of time and, along with Figure 7, illustrates an alternative method to that of the above embodi^¬ ments, in which, instead of completely omitting use of the E- DPCCH, a modified E-DPCCH can be transmitted on the first N E-DPCCH TTIs and subsequently a number of E-DPDCHs can be transmitted on subsequent TTIs. In other words, the E- DPCCH (s) is time multiplexed with the E-DPDCH (s). This is illustrated more clearly in Figure 7, which shows that, for example, during the first two TTIs, the E-DPCCH is transmitted and then for the next six TTIs only the E-DPDCH is trans^¬ mitted without the E-DPCCH (different transmission combinations of the E-DPDCH and E-DPCCH to that shown in Figure 7 are possible, however) . However, the general control channel DPCCH is always transmitted. Various alternative embodiments of this "modified E-DPCCH" method are described below.

In one embodiment, a fixed number of E-DPDCH repetitions is used (e.g. six repetitions). Therefore, no RSN is required at all. An additional in-phase component of the modified E- DPCCH is provided to signal the number of repetitions. In the NodeB, receiver Chase Combining or Incremental Redundancy of the repeated data is performed to enhance the coverage range. A further advantage of this embodiment is that ACK/NACK signalling via E-HICH is only required at the end of the repetition sequence in the downlink direction or, alternatively, no HARQ component is used at all, which means that E-HICH can be avoided completely. The E-TFCIs for the re- stricted subset of E-TFCs are transmitted on a quadrature phase E-DPCCH in the first TTI (s). In other words, the mo^¬ bile station UE transmits the E-DPCCH, which contains an indication of the transport format and/or the number of automatic retransmissions that should take place. The mobile station UE also signals the format of the first transmission and automatic retransmissions to the base station NodeB in the modified E-DPCCH.

In another embodiment, an additional in-phase component can be used for a modified E-DPCCH to signal if repetition is used and, if so, the number of repetitions. This embodiment does not use additional RRC signalling to define the activa^¬ tion and schedule of repetitions. The E-TFCIs for the restricted subset of E-TFCs and the two RSN bits are used in combination with incremental redundancy and transmitted on the quadrature phase E-DPCCH in the first TTI (s).

Alternatively, the E-TFCI is defined with a restricted subset of E-TFCs such that the E-TFCI could be used to indicate the usage of repetition as well as the E-TFC from the restricted subset. The RSN, which is redundant when a fixed number of transmrssions are used, could be reused as an indicator of the number of retransmissions to be expected.

As the mobile station UE may at any time choose to switch between the first and second modes of operation, for the above embodiments, a cyclic redundancy check (CRC) may be included in the additional in-phase signalling to distinguish legacy E-DPCCH signalling from extended E-DPCCH signalling. If the CRC fails, it can be determined that the first mode of operation is being used and if the CRC does not fail, it can be determined that the second mode of operation is being used. As an alternative to a CRC, a radio resource control (RRC) re-configuration can be used by the radio network controller RNC to inform the mobile station UE and base station NodeB that a repetition mode is m use and that the E-TFCI should be re-interpreted as referring to an E-TFC from a reduced set, as well as an indication of whether the number of trans^¬ missions of the E-TFC is fixed or dependent on ACK/NACK feedback.

Furthermore, the base station NodeB can signal activa- tion/deactivation of the second mode of operation to the mobile station UE via HS-SCCH orders. This is initiated by the MAC scheduler in the NodeB. The MAC scheduler can decide to activate/deactivate the second mode of operation based on the UPH value transmitted by the mobile station UE in the sched- uling information field of the MAC-e/MAC-i packet. In soft handover situations, other base stations in the network in^¬ volved in the active set (communication with the mobile station UE) may blindly detect the non-existence of the E-DPCCH to identify the usage of the second operating mode. Alterna- tively, the fame protocol may be used to inform the other base stations via the controlling RNC (CRNC) controlling all base stations in the network that the second operating mode is in use.

During the second operating mode the Radio Resource Controller RRC in the base station NodeB signals to the mobile station UE information including the available data format, tim^¬ ing of the first transmission and the number of automatic re- transmissions.

Alternatively, an indicator could be used on the DPCCH to in^¬ dicate that no transmission is taking place via the E-DPCCH. In this case, the mobile station UE itself can decide when to use transmission without the E-DPCCH dependent on its UPH.

It can be seen from both Figures 5 and 6 that, according to the above described embodiments of the invention, the maximum transmit power of the mobile station UE is not reached so that there is enough power PGain left over for transmitting at least a minimum data rate, even in low power situations where the mobile station UE is a long way from the base station NodeB. Although the invention has been described hereinabove with reference to specific embodiments, it is not limited to these embodiments and no doubt further alternatives will occur to the skilled person that lie within the scope of the invention as claimed. LIST OF ABBREVIATIONS

ACK Acknowledgement

CPC Continuously Packet Connected or Continuous Packet Connectivity

CRNC Controlling Radio Network Controller

DCH Dedicated Channel

DL Downlink

DPCCHDedicated Physical Control Channel E-DCH Enhanced Dedicated Channel

E-DPCCH E-DCH Dedicated Physical Control Channel

E-DPDCH E-DCH Dedicated Physical Data Channel

E-HICH E-DCH HARQ Acknowledgement Indicator

Channel

E-TFCI E-DCH Transport Format Indicator

E-TFCE-DCH Transport Format

HSDPAHigh Speed Downlink Packet Access

HS-SCCH High Speed Physical Downlink Shared Control Channel

HSUPAHigh Speed Uplink Packet Access

MAC Medium Access Control

NACK Negative Acknowledgement

NBAP NodeB Application Part

NST Non-scheduled transmission

RL Radio Link

RRC Radio Resource Control

RSN Retransmission Sequence Number

SHO Soft Handover

TFCI Transport Format Combination Indicator

TTI Transmission Time Interval

UE User Equipment

UPH UE power headroom

Claims

1. A method of transmitting a signal from a mobile station to a network entity in a communications network, wherein the network has a first operating mode using a general control channel (DPCCH) , a packet data associated control channel (E- DPCCH) and a packet data channel (E-DPDCH) , in which a first transmission and hybrid ARQ retransmissions from the mobile station to the network entity are made on the packet data channel (E-DPDCH) and signalling for the packet data and the hybrid ARQ retransmissions is transmitted on the packet data associated control channel (E-DPCCH) ,

and a second operating mode, wherein in the second operating mode

- the packet data associated control channel (E-DPCCH) is prevented from being transmitted during at least part of a time allocated for data transmissions and

the format of the transmission and/or the number of retransmissions is predetermined or signalled between the network entity and the mobile station.

2. The method according to claim 1, wherein the mobile station comprises means to transmit automatic retransmissions on the packet data channel (E-DPDCH) without acknowledgement feedback from the network entity in the second operating mode .

3. The method according to claim 2, wherein the mobile station comprises means to transmit the packet data associated control channel (E-DPCCH) containing at least one of an indication of a transport format and a number of automatic re^¬ transmissions in the second operating mode.

4. The method according to claim 2 or claim 3, wherein the mobile station comprises means for signalling the format of the first transmission and automatic retransmissions in the second operating mode to the network entity in the packet data associated control channel (E-DPCCH) and wherein the contents of the packet data associated control channel (E- DPCCH) are modified compared to the first operating mode.

5. The method according to any one of claims 2 to 4, wherein the mobile station further comprises means to transmit signalling related to the first transmission and automatic retransmissions, in the second operating mode, to the network entity in a control channel associated with the packet data channel (E-DPCCH) that is time multiplexed with the packet data channel (E-DPCCH) .

6. The method according to claim 1, wherein the mobile station further comprises means for signalling, in the second operating mode, packet data related signalling comprising at least one of (i) the transport format of the first trans^¬ mission or (ii) a number of automatic retransmissions or (in) a retransmission sequence number to the network entity.

7. The method according to claim 6, wherein the mobile sta- tion comprises means for transmitting the packet data related signalling, in the second operating mode, to the network entity in signalling bits of the general control channel (DPCCH) and wherein the contents of the general control channel (DPCCH) is modified compared to the first operating mode.

8. The method according to claim 7, wherein the network entity comprises means for detecting the presence of the control channel carrying signalling associated with the packet data channel.

9. The method according to any of claims 2 to 8, wherein the network entity comprises means for signalling to the the mobile station at least one of the information of the available data format, a timing of the first transmissions and a number of automatic retransmissions in the second operating mode.

10. The method according to any of claims 1 to 9 wherein the network entity comprises means for switching the mobile station between the first and second operating mode.

11. The method according to any of claims 1 to 10, wherein the mobile station comprises means for autonomously selecting the first or the second operating mode.

12. The method according to any of claims 1 to 11, wherein the network entity comprises means for signalling a modified set of transmission configuration parameters to the mobile station for use in the second operating mode.

13. A mobile station, comprising a transmitter, a receiver, and a transmission controller and configured to operate in a first operating mode in which the transmitter is adapted to transmit a general control channel (DPCCH) , to transmit a first transmission and hybrid ARQ retransmissions from the mobile station to a network on a packet data channel (E- DPDCH) , and to transmit signalling for the packet data and for the hybrid ARQ retransmissions on a packet data associated control channel (E-DPCCH) ,

and the mobile station is further configured to operate in a second operating mode, in which the transmission controller is further configured to prevent the packet data associated control channel (E-DPCCH) from being transmitted during at least part of a time allocated for data transmissions and

is configured to use a number of retransmissions and/or transmission format that is either received at the receiver, predetermined or determined by the mobile station.

14. A network entity configured to operate in a first operating mode using a general control channel (DPCCH), a packet data associated control channel (E-DPCCH) and a packet data channel (E-DPDCH) and comprising a receiver for receiving a first transmission and hybrid ARQ retransmissions from a mobile station on the packet data channel (E- DPDCH) and for receiving signalling for the hybrid ARQ retransmissions on the packet data associated control channel (E-DPCCH) , wherein the network entity is further configured to operate in a second operating mode in which the receiver does not receive the packet data associated control chan- nel (E-DPCCH) during at least part of a time allocated for data transmissions and the network entity further comprises resource control means for signalling the format of the transmission and/or the number of retransmissions to the mo^¬ bile station during the second mode of operation.