HK1171312B - Method and arrangement in a wireless communication system - Google Patents

Description

Method and arrangement in a wireless communication system

Technical Field

The present invention relates to a method and an arrangement in a base station and a method and an arrangement in a user equipment. In particular, it relates to a mechanism for reducing load and interference on a communication channel when transmitting scheduling requests.

Background

Standardization of fourth generation (4G) cellular networks is under the name international mobile telecommunications advanced (IMT advanced). IMT advanced promises next generation mobile networks to have high data rates, seamless connectivity, and mobile communications within heterogeneous networks.

For many applications, short access delays play a critical role in providing good end-user performance. The IMT-advanced latency requirement states that the one-way radio access delay between the mobile terminal and the base station should be below 10 ms.

Long Term Evolution (LTE) networks, as defined by the third generation partnership project (3GPP), provide improved bit rates with lower access delays than older technologies. For a release 8 user equipment Unit (UE), if the user equipment unit is scheduled, an IMT-advanced delay target is reached. If the user equipment needs to request resources, the delay target is not reached.

The access technology of LTE is based on Orthogonal Frequency Division Multiplexing (OFDM) in the downlink and single carrier frequency division multiple access (SC-FDMA) in the uplink.

In this context, the expression "uplink" is used for signal transmission from the user equipment to the base station, while the expression "downlink" is used for signal transmission in the opposite direction, i.e. from the base station to the user equipment. A base station may also be referred to as an eNodeB or eNB in an LTE environment.

Resources are allocated to user equipments on the downlink and uplink dynamically on a 1ms basis or semi-persistently over a period longer than 1 ms. The eNB performs resource scheduling and it takes into account the user equipment data buffer and the radio propagation characteristics of each user equipment.

Fig. 1 shows a standard uplink scheduling procedure in LTE. When new data arrives in an empty user equipment buffer or the data belongs to a higher priority logical channel group than existing data, the user equipment triggers a Buffer Status Report (BSR) to report its buffer size. The user equipment triggers a Scheduling Request (SR) if it has no uplink resources to transmit a buffer status report.

The scheduling request may be sent on a dedicated scheduling request channel (D-SR) or on a contention-based random access channel (RA-SR). The use of a dedicated scheduling request channel requires that the user equipment is uplink synchronized and that the user equipment has been assigned a scheduling request channel on the Physical Uplink Control Channel (PUCCH). The dedicated scheduling request resources are assigned with Radio Resource Control (RRC) protocol with periodicity current values of 5, 10, 20, 40 and 80 milliseconds in LTE release 8. In LTE release 9, even values shorter than 5 milliseconds are possible. When the eNB has received the scheduling request, it may schedule the user equipment and transmit an initial grant. With the initial grant, the user equipment can finally transmit a buffer status report with it.

In summary, before scheduling user equipments, a number of steps have to be taken. This increases the access delay in the uplink. When in uplink synchronization, the scheduling request periodicity in PUCCH is one of the largest contributing factors in delay increase. In order to obtain the best performance for certain applications, the scheduling request periodicity should be chosen to be very short.

In the 3GPPTS36.321MAC specification v8.6.0, a scheduling request is pending from the time when it is triggered until the time when it is cancelled. The scheduling request is cancelled when uplink scheduling resources are available for a new transmission.

When a scheduling request is pending during each subframe when the user equipment unit has valid scheduling request resources on the PUCCH, the user equipment unit instructs the physical layer to signal the scheduling request. This results in a physical transmission of a scheduling request. In the example depicted in fig. 1, the scheduling request periodicity is fixed to 5ms and the first opportunity to transmit a scheduling request on PUCCH is in subframe t 0. After the eNB has received the scheduling request, a typical processing time of 3ms is assumed before scheduling the user equipment unit and transmitting the grant. The user equipment unit has the next scheduling request opportunity at t1 after 5 ms. Since the user equipment unit has not cancelled the scheduling request yet, it will retransmit the scheduling request. Thus, configuring the scheduling request periodically to 5ms results in a physical transmission of the scheduling request at least twice. This generates a large unnecessary load on the PUCCH.

Mechanisms for inhibiting transmission of scheduling requests and network configurations for such mechanisms are known, see WO2009038381a2 "method for triggering schedulneslingreques for effecting communication session". However, in WO2009038381a2, the only conditions mentioned when transmission of scheduling requests is prohibited are when uplink synchronization, i.e. the time alignment timer is expected to expire soon, or when the total number of scheduling request transmissions has exceeded a certain number. The idea of WO2009038381a2 is to start random access instead if the scheduling request is barred.

Disclosure of Invention

It is therefore an object of the present invention to provide mechanisms for improving performance in a wireless communication system.

According to a first aspect of the present invention, the object is achieved by a method in a user equipment for transmitting a scheduling request to a base station. The base station is adapted to serve the user equipment. The user equipment further includes a scheduling request transmission trigger and is configured to transmit a scheduling request to the base station. However, scheduling requests are transmitted only at certain predetermined scheduling request occasions. The method includes initiating the scheduling request transmission trigger. Also, a scheduling request is transmitted to the base station at a next occurring scheduling request occasion as a response to the initiated trigger. In addition, a scheduling request prohibit timer included in the user equipment is started when the scheduling request is transmitted to the base station for the first time. Further, any further scheduling request retransmissions at future scheduling request occasions are prohibited when the scheduling request prohibit timer is running.

According to a second aspect of the present invention, the object is achieved by an arrangement in a user equipment for transmitting a scheduling request to a base station. The base station is adapted to serve the user equipment. The user equipment further includes a scheduling request transmission trigger and is configured to transmit a scheduling request to the base station. However, scheduling requests are transmitted only at certain predetermined scheduling request occasions. The arrangement includes a scheduling request transmission trigger. The scheduling request transmission trigger is configured to trigger a scheduling request transmission. Also, the arrangement comprises a transmitter. The transmitter is configured to transmit a scheduling request to the base station as a response to the initiated trigger at a next occurring scheduling request occasion. Further, the arrangement comprises a scheduling request prohibit timer. The scheduling request prohibit timer is configured to start when the scheduling request is transmitted and prohibit any further scheduling request retransmissions at future scheduling request occasions when the scheduling request prohibit timer is running.

According to a third aspect of the present invention, the object is achieved by a method in a base station for assisting a user equipment in transmitting a scheduling request to the base station. The base station is adapted to serve the user equipment. The user equipment is configured to transmit scheduling requests to the base station only at certain predetermined scheduling request occasions. The method comprises determining a factor k to be transmitted to the user equipment enabling the user equipment to calculate a scheduling request prohibit timer length. Additionally, the method further comprises transmitting the determined factor k to the user equipment. Further, the method comprises scheduling the user equipment when a scheduling request is received from the user equipment.

According to a fourth aspect of the present invention, the object is achieved by an arrangement in a base station, for assisting a user equipment in transmitting a scheduling request to the base station. The base station is adapted to serve the user equipment. The user equipment is configured to transmit scheduling requests to the base station only at certain predetermined scheduling request occasions. The arrangement comprises a determination unit. The determining unit is configured to determine a factor k to be transmitted to the user equipment in order for the user equipment to calculate a scheduling request prohibit timer length. In addition, the arrangement comprises a transmitter. The transmitter is configured to transmit the determined factor k to the user equipment. Additionally, the arrangement comprises a scheduler. The scheduler is configured to schedule the user equipment when a scheduling request is received from the user equipment.

By starting the scheduling request prohibit timer when the user equipment transmits a scheduling request on the PUCCH for the first time, the load on the PUCCH can be significantly reduced. In addition, by configuring the scheduling request prohibit timers of different user equipments with different lengths, the retransmissions of scheduling requests are also spread in time. Thereby, the performance of the wireless communication system is improved.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention.

Drawings

The present invention is described in more detail with reference to the appended drawings illustrating exemplary embodiments of the invention, and wherein:

fig. 1 is a schematic block diagram illustrating communications within a prior art wireless communication system.

Fig. 2 is a schematic block diagram illustrating an embodiment of a wireless communication system.

Fig. 3 is a combined signaling and flow diagram that illustrates radio signal transmission, in accordance with some embodiments.

Fig. 4A is a combined signaling and flow diagram illustrating radio signal transmission according to some embodiments.

Fig. 4B is a combined signaling and flow diagram illustrating radio signal transmission according to some embodiments.

Fig. 5 is a flow chart illustrating a method embodiment in a user equipment.

Fig. 6 is a schematic block diagram illustrating an embodiment of a user equipment arrangement.

Fig. 7 is a flow chart illustrating a method embodiment in a base station.

Fig. 8 is a schematic block diagram illustrating a base station arrangement embodiment.

Detailed Description

The present invention is defined as a method and an arrangement in a user equipment and a method and an arrangement in a base station, which can be put into practice in the embodiments described below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey the scope of the invention to those skilled in the art.

Other objects and features of the present invention will become apparent from the following detailed descriptions considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

Fig. 2 depicts an exemplary wireless communication system 100, such as, for example, an IMT-advanced, E-UTRAN, LTE-Adv, a third generation partnership project (3GPP) WCDMA system, enhanced data rates for global system for mobile communications/GSM evolution (GSM/EDGE), Wideband Code Division Multiple Access (WCDMA), worldwide interoperability for microwave access (WiMax), or Ultra Mobile Broadband (UMB), to name just a few of any of the possible options.

The wireless communication system 100 comprises a base station 28 and a user equipment 30 adapted to communicate with each other within a cell over at least one radio channel. It will be appreciated that the wireless communication system 100 may generally include many other nodes, such as other base station nodes, and in some embodiments also other nodes, such as control nodes. Only a strictly limited selection of nodes 28, 30 is shown in fig. 2 for simplicity.

The base station 28 may for example be referred to as NodeB, evolved NodeB, (eNodeB or eNB), base transceiver station, access point base station, base station router, or any other network element capable of communicating with the user terminals 30 within a cell, e.g. according to the radio access technology and terminology used. In the remaining description, the term "base station" will be used with respect to base station 28 to facilitate an understanding of the present methods and arrangements.

Base station 28 includes one or more transceivers configured to transmit frames of information for transmission over a radio interface. For downlink transmission to the user terminal 30, the transceiver feeds multiple antennas for providing multiple sub-carriers. The transceiver thus transmits the symbols of the sub-frames of the frame on the downlink in the frequency domain on a plurality of sub-carriers.

According to some embodiments, base station 28 may also include a base station frame handler. The subframe handler may be configured to prepare or format a frame of information for transmission by the transceiver on the downlink to the user equipment 30. The optional base station frame handler has access to or may in some implementations include a resource manager/scheduler. The resource manager/scheduler maintains and allocates resources for the user equipment 30 and other user equipment units (not shown) and schedules the resources. One of the types of resources monitored by the resource manager/scheduler is Physical Uplink Control Channel (PUCCH) resources. The PUCCH carries uplink control information and supports multiple formats.

The user equipment 30 may be, for example, a wireless communication terminal, a mobile cellular telephone, a Personal Digital Assistant (PDA), a wireless platform, a laptop computer, a computer, or any other kind of device capable of communicating wirelessly with the base station 28.

The user equipment 30 shown in fig. 2 may comprise a transceiver. The transceiver may comprise or be connected to a user equipment antenna. According to some embodiments, the user equipment 30 may also include a user equipment frame handler. The wireless terminal frame handler may receive and process downlink subframes and may prepare and format uplink subframes. At least one uplink subframe prepared by the user equipment frame handler and transmitted by the transceiver from the user equipment 30 to the base station 28 carries a Physical Uplink Control Channel (PUCCH).

The user equipment 30 may also comprise a scheduling request prohibit timer configured and operable to prohibit the user equipment unit 30 from transmitting a scheduling request too early after a previous scheduling request attempt.

In the following, the inventive method and arrangement are further elucidated with particular reference to IMT-advanced systems, and more specifically with respect to the uplink in IMT-advanced, i.e. for the link from the user equipment 30 to the base station 28. However, it is obvious to a person skilled in the art that the corresponding concept may also be applied in other wireless communication systems 100.

The present methods and arrangements provide a scheduling request prohibit timer that is started when the user equipment 30 has transmitted a scheduling request to the base station 28 for the first time on the PUCCH. The idea of the scheduling request prohibit timer is to prohibit the user equipment 30 from transmitting a scheduling request too early after a previous scheduling request attempt.

Thereby, the load on the PUCCH can be significantly reduced, since no redundant scheduling requests are transmitted. In addition, according to some embodiments, the scheduling request prohibit timers of different user equipments 30 may be configured with different timer lengths. Thus, retransmissions of scheduling requests from different user equipments 30 are spread in time, so that collisions between user equipment transmissions may be avoided.

Fig. 3 is a combined signaling and flow diagram that illustrates radio signal transmission between a user equipment 30 and a base station 28, according to some embodiments. The purpose of this illustration is to provide a general overview of the methods of the invention and the functionality involved. Also, there is illustrated a general purpose and exemplary environment in which the methods and arrangements of the present invention may be implemented.

Data is received in a user equipment buffer. The reception and/or detection of data transmitted in the user equipment buffer triggers the transmission of a scheduling request SR to the base station 28. The scheduling request SR is used to request uplink scheduling resources for transmitting the received/detected data.

However, the user equipment 30 is only allowed to transmit scheduling requests SR at certain predetermined scheduling request occasions t0, t1, t2, t3, t 4. According to different embodiments, there may be an infinite number of possible predetermined scheduling request occasions t0, t1, t2, t3, t4,. gtoreq, t ∞, or a finite number of scheduling request occasions t0, t1, t2, t3, t4,. gtoreq, t ∞, where t ∞ is limited to t-max.

Thus, the scheduling request SR has been triggered due to the data received in the user equipment buffer. In the example illustrated in fig. 3, the triggered scheduling request SR is not allowed to be transmitted until the next possible scheduling request occasion t 0. Thus, the scheduling request SR will be considered as pending until it is cancelled.

When data is assembled and this data comprises a buffer status report including the buffer status up to the last event that triggered the buffer status report, or when the uplink grant can accommodate all pending data available for transmission, all pending scheduling requests SR can be cancelled and the scheduling request prohibit timer can be stopped.

If the user equipment 30 does not have valid PUCCH resources for transmitting the configured scheduling request SR in any predetermined scheduling request occasion t0, t1, t2, t3, t4,. -, t ∞, then the random access procedure may be initiated and all pending scheduling requests may be cancelled. Otherwise, if the user equipment 30 has valid PUCCH resources for at least some of the predetermined scheduling request occasions t0, t1, t2, t3, t4,. t.,. t ∞ of scheduling requests SR, and no scheduling request prohibit timer 40 is running, the generated scheduling request SR may be transmitted at the next scheduling request occasion t 0.

The scheduling request prohibit timer 40 is started when the triggered scheduling request SR is transmitted at t0 on the PUCCH. The scheduling request prohibit timer 40 is included in the user equipment unit 30. When the scheduling request prohibit timer 40 is running, the user equipment unit 30 is not allowed to retransmit the scheduling request SR. According to some embodiments, the user equipment 30 may set the scheduling request prohibit timer 40 to 0 (zero) when a scheduling request SR is triggered and no other scheduling requests SR are pending.

When the scheduling request prohibit timer 40 expires, the user equipment unit 30 is allowed to retransmit/retransmit the scheduling request SR on the PUCCH. When it expires, the timer 40 is stopped, except for the following: when the user equipment unit 30 cancels the scheduling request SR, but also when the scheduling request prohibit timer 40 can be stopped.

According to some embodiments, the scheduling request prohibit timer 40 may be set to 0 when it is started, and then incremented for each elapsed time until a predetermined maximum timer value is reached. However, according to some embodiments, the scheduling request prohibit timer 40 may be set to a predetermined maximum timer value when started and then count down to 0, or alternatively, reach any other predetermined minimum timer value.

The scheduling request SR is not retransmitted as long as the scheduling request prohibit timer 40 is running. In the example illustrated in fig. 3, the scheduling request SR is cancelled at t1, t2, and t 3.

When the base station 28 receives a scheduling request SR from the user equipment 30, the base station 28 schedules the user equipment 30. Thereby, a grant may be generated and transmitted to the user equipment 30 such that the user equipment 30 may be allocated resources for uplink transmission of received data in the user equipment buffer.

When the user equipment 30 receives the grant, data is transmitted to the base station 28 at the allocated resources.

Fig. 4A is a combined signaling and flow diagram illustrating radio signal transmission according to some embodiments.

Fig. 4A illustrates the use of the scheduling request prohibit timer 40 when a grant is received in a subframe, and the stopping of the scheduling request prohibit timer 40 when the scheduling request SR is cancelled. In other words, in fig. 4A, the scheduling request prohibit timer 40 prohibits the user equipment 30 from transmitting the scheduling request SR twice. When the scheduling request SR is cancelled, the scheduling request prohibit timer 40 is stopped. If a new scheduling request SR is triggered after stopping the scheduling request timer, the user equipment 30 is allowed to transmit the scheduling request SR again.

Fig. 4B is a combined signaling and flow diagram illustrating radio signal transmission according to some embodiments.

In the illustration of fig. 4B, the scheduling request prohibit timer 40 expires before the scheduling request SR is cancelled. That is, the scheduling request prohibit timer 40 prohibits the user equipment unit 30 from transmitting the scheduling request SR at the sub-frames t1 and t 2. The scheduling request prohibit timer 40 is stopped when it expires. After the expiry of the scheduling request prohibit timer 40, the user equipment 130 is allowed to transmit the pending scheduling request SR again.

Thus, if the SR prohibit timer 40 has expired and there are still pending scheduling requests SR, they are allowed to be retransmitted. If the SR prohibit timer 40 is stopped due to the cancellation of the scheduling request SR, there is no pending scheduling request SR, but when a newly triggered scheduling request SR arrives, it may be transmitted, and the SR prohibit timer 40 may be started again, etc.

A downside of the scheduling request prohibit timer 40 is that if the base station 28 misses the scheduling request SR, retries are delayed. In order to avoid too long a delay in case of missing a scheduling request SR, the scheduling request prohibit timer 40 may not be too long, according to some embodiments. On the one hand, introducing the scheduling request prohibit timer 40 may reduce the load on PUCCH and, thus, the need for retransmission of the scheduling request SR is smaller.

In addition to avoiding unnecessary scheduling requests SR and thus loading PUCCH too much, the scheduling request prohibit timer 40 may be utilized when extending retries of missed scheduling requests SR in the time domain. Consider two user equipment units located in adjacent cells transmitting scheduling requests SR on the same PUCCH resource at the same time. Due to interference, the base station 28 in the corresponding cell may not be able to detect which user equipment 30 is transmitting the scheduling request SR and thus does not schedule any user equipment 30. If the two user equipment units have the same scheduling request periodicity, they simultaneously retransmit the scheduling request SR, again resulting in high interference. The correlation of scheduling request periodicity interference with hysteresis can be avoided if the two user equipment units have different scheduling request prohibit timer lengths.

The scheduling request prohibit timer 40 may take various example embodiments and may have different implementations. The following are possible non-limiting and non-exhaustive example implementations and/or configurations.

Example implementation 1: the length of the scheduling request prohibit timer may be fixed to some common value, such as, for example, 10ms, or the length of the scheduling request periodicity.

Example implementation 2: the scheduling request prohibit timer 40 has a fixed length and it is configured by the base station 28 with RRC. A possible value may be k times the scheduling request periodicity, where k may be signaled by RRC. Having 4 different possible values k-0, 1, 2, 3 may give the base station 28 the flexibility to decide how it wants the behavior of the user equipment 30, according to some embodiments.

Example implementation 3: the scheduling request prohibit timer length may be, for example, (k + l) times the scheduling request periodicity, where k is configured by the base station 28 and l is a random portion selected by the user equipment 30, ranging between [0, 1., m ]. According to some embodiments, an example appropriate value for m may be 4.

Example implementation 1 may be the simplest solution to avoid unnecessary scheduling requests SR. Example implementation 2 may provide base station 28 with more flexibility to configure different user equipment 30 with different values and thereby avoid retrying scheduling requests SR at the same time. There is also a way to handle the trade-off between avoiding unnecessary retries and increasing the necessary retry delay, where the trade-off can be viewed differently for different services. Finally, in case of having a random portion in the scheduling request prohibit timer 40 as proposed in example implementation 3, the interference between neighboring cells due to scheduling request SR retry collision can be reduced.

The base station 28 may thus configure the scheduling request prohibit timer 40 such that the user equipment 30 does not transmit unnecessary scheduling requests SR on PUCCH immediately after a previous attempt. In this way, the load on the PUCCH can be reduced and unnecessary interference avoided. Furthermore, having a random portion, the scheduling request prohibit timer 40 enables scheduling request SR retransmission attempts by different user equipments 30 to occur at different times.

Fig. 5 is a flow chart illustrating an embodiment of method steps 501 and 506 performed in the user equipment 30 for transmitting a scheduling request SR to the base station 28. The base station 28 is configured to serve user equipment 30. The user equipment 30 includes a scheduling request transmission trigger 620. In addition, the user equipment 30 is configured to transmit scheduling requests SR to the base station 28 only at certain predetermined scheduling request occasions t0, t1, t2, t3, t 4.

The base station 28 and the user equipment 30 are comprised in a wireless communication system 100. According to some embodiments, the wireless communication system 100 may be, for example, an IMT-advanced or LTE radio network, and the base station 28 may be, for example, an evolved node B, eNB.

The user equipment 30 comprises a scheduling request prohibit timer 40.

In order to appropriately transmit the scheduling request SR to the base station 28, the method may comprise several method steps 501-506.

It is noted, however, that some of the described method steps are optional and are included in only some embodiments. Further, it is noted that the method steps 501-506 may be performed in a slightly different temporal order, and that some of them (e.g. steps 502 and 503), or even all of them, may be performed simultaneously or in a changed or rearranged temporal order. The method may comprise the steps of:

step 501

This step is optional and may be included in only some embodiments.

The scheduling request prohibit timer 40 may be configured with a scheduling request prohibit timer length such that the scheduling request prohibit timer 40 expires when the configured scheduling request prohibit timer length has elapsed after the scheduling request prohibit timer 40 has been started.

Step 502

A scheduling request transmission trigger 620 is initiated. Thereby, a scheduling request transmission is triggered, which scheduling request SR is to be transmitted at the next occurring scheduling request occasions t0, t1, t2, t3, t4,. -, t ∞, when the user equipment 30 is allocated resources for transmitting the scheduling request SR.

According to some embodiments, the scheduling request transmission trigger 620 may be initiated when there is data to send in the user equipment buffer.

Step 503

The scheduling request SR is transmitted to the base station 28 at the next occurring scheduling request occasions t0, t1, t2, t3, t 4. The scheduling request SR is transmitted in response to the initiated trigger 620.

Step 504

The scheduling request prohibit timer 40 contained in the user equipment 30 is started. The scheduling request prohibit timer 40 is started when the scheduling request SR is transmitted to the base station 28 for the first time.

According to some embodiments, the scheduling request prohibit timer 40 may be configured to fix the scheduling request prohibit timer length.

The scheduling request prohibit timer 40 may be configured to a scheduling request prohibit timer length equal to the time between two scheduling request occasions t0, t1, t2, t3, t4,. gtoreq, t ∞ multiplied by a factor k such that:

the scheduling request prohibit timer length k (t2-t 1).

According to some embodiments, the scheduling request prohibit timer 40 may be configured to a scheduling request prohibit timer length equal to the result of the time between two scheduling request occasions t0, t1, t2, t3, t4,.. gt∞ multiplied by a factor k operated by a random variable l such that:

the scheduling request prohibit timer length is (k + l) · (t2-t 1).

The factor k may optionally be received from the base station 28. The random variable l may be randomly generated by the user equipment 30.

The factor k may range between 0 and infinity such that: k [0, 1., ∞ ], wherein the factor k may be transmitted from the base station 28 via Radio Resource Control (RRC), and wherein the scheduling request SR may be transmitted on a Physical Uplink Control Channel (PUCCH).

Step 505

When the scheduling request prohibit timer 40 is running, i.e., not stopped, any further scheduling request retransmissions are prohibited at any future scheduling request occasions t0, t1, t2, t3, t 4.

Thus, by not retransmitting the scheduling request SR, the traffic load on the channel is reduced, which results in an increase of the overall capacity within the wireless communication network 100.

Step 506

This step is optional and may be included in only some embodiments.

The scheduling request prohibit timer 40 is stopped when the scheduling request SR is cancelled or when the scheduling request prohibit timer 40 expires.

Fig. 6 schematically illustrates an arrangement 600 in the user equipment 30. The user equipment 30 is configured to perform the method steps 501-506 for transmitting the scheduling request SR to the base station 28. The base station 28 is adapted to serve a user equipment 30. The user equipment 30 is configured to transmit scheduling requests SR to the base station 28 only at certain predetermined scheduling request occasions t0, t1, t2, t3, t 4. The base station 28 and the user equipment 30 are comprised in a wireless communication system 100. The wireless communication system 100 may be, for example, an IMT-advanced or LTE radio network. According to some embodiments, the base station 28 may be, for example, an evolved node B, eNB.

In order to correctly perform the method steps 501 and 506, the user equipment arrangement 600 comprises a plurality of units such as, for example, a scheduling request transmission trigger 620. The scheduling request transmission trigger 620 is configured to trigger a scheduling request transmission. Further, the user equipment arrangement 600 comprises a transmitter 630. The transmitter 630 is configured to transmit a scheduling request SR to the base station 28 as a response to the triggered scheduling request transmission at the next occurring scheduling request occasions t0, t1, t2, t3, t 4. Also, additionally, the arrangement 600 comprises a scheduling request prohibit timer 40. The scheduling request prohibit timer 40 is configured to start when the scheduling request SR is transmitted for the first time and prohibit any further scheduling request retransmissions at future scheduling request occasions t0, t1, t2, t3, t 4.

According to some embodiments, the arrangement 600 may further comprise a configuration unit 610. The optional configuring unit 610 is adapted to configure the scheduling request prohibit timer 40 with a scheduling request prohibit timer length such that the scheduling request prohibit timer 40 expires when the configured scheduling request prohibit timer length has elapsed after the scheduling request prohibit timer 40 has been started. According to some embodiments, configuration unit 610 may receive the scheduling request prohibit timer length from base station 28. However, according to some embodiments, the scheduling request prohibit timer length may be predetermined or calculated based on the scheduling request prohibit timer length received from the base station 28.

Additionally, according to some embodiments, the arrangement 600 may comprise a receiver 44. Receiver 44 is configured to receive signals from base station 28.

According to some embodiments, the arrangement 600 may optionally comprise a buffer 640. The buffer 640 is configured to receive and hold data to be transmitted.

Further, the arrangement 600 may comprise a transmitter 630. According to some embodiments, transmitter 630 is configured to transmit signals, for example, to base station 28.

Also, the arrangement 600 may include a frame handler 46. The frame handler 46 is configured to receive and process downlink subframes and prepare and format uplink subframes.

Optionally, the arrangement 600 further may also comprise a processor 660. Processor 660 may be represented, for example, by a Central Processing Unit (CPU), processing unit, microprocessor, or other processing logic that may interpret and execute instructions. Processor 660 may perform all processing functions for inputting, outputting, and processing data, including data buffering and device control functions, such as call processing control, user interface control, and so forth.

It is to be noted that any internal electronics of the user equipment 30 and/or the user equipment arrangement 600 which are not necessary for the understanding of the inventive method according to method steps 501 and 506 have been omitted from fig. 6 for reasons of simplicity. Further, it is to be noted that some of the described units 40-660 comprised within the arrangement 600 in the user equipment 30 are considered as separate logical entities, but not necessarily separate physical entities. As just one example, the receiver 44 and the transmitter 630 may be contained or co-arranged within the same physical unit, a transceiver, which may include a transmitter circuit and a receiver circuit, which respectively transmit outgoing radio frequency signals and receive incoming radio frequency signals via an antenna. The radio frequency signals transmitted between the base station 28 and the user equipment 30 may include both traffic and control signals, e.g., paging signals/messages for incoming calls, which may be used to establish and maintain a voice call communication with another party, or to transmit and/or receive data, such as SMS, e-mail or MMS messages, with a remote user equipment.

The method steps 501- > 506 in the user equipment 30 may be implemented by one or more processors 660 in the user equipment 30 together with computer program code for performing the functions of the method steps 501- > 506 of the invention. Thus, a computer program product, such as e.g. a computer program storage medium, may comprise instructions for performing the method steps 501 and 506 in the user equipment 30 and may transmit the scheduling request SR to the base station 28.

The above mentioned physical and tangible computer program product may be provided for example in the form of a data carrier carrying computer program code which, when loaded into the processor 660, executes the method steps according to the inventive solution. The data carrier may be, for example, a hard disk, a cd rom disc, a memory stick, an optical storage device, a magnetic storage device or any other suitable medium, such as a disk or tape, which can hold machine-readable data. The computer program code may also be provided as program code on a server and downloaded to the user equipment 30 remotely, e.g. over an internet or an intranet connection.

Further, a computer program product comprising instructions for carrying out at least some of the method steps 501 and 506 may be used for implementing the previously described method in a user equipment 30 for transmitting a scheduling request SR to a base station 28, when the computer program product is run on a processor 660 comprised in the user equipment 30.

Fig. 7 is a flow chart illustrating an embodiment of method steps 701 and 703 performed in the base station 28 for assisting the user equipment 30 to transmit the scheduling request SR to the base station 28. The base station 28 is adapted to serve a user equipment 30. The user equipment 30 is configured to transmit scheduling requests SR to the base station 28 only at certain predetermined scheduling request occasions t0, t1, t2, t3, t 4. The base station 28 and the user equipment 30 are comprised in a wireless communication system 100. According to some embodiments, the wireless communication system 100 may be, for example, an IMT-advanced/LTE-advanced radio network, and the base station 28 may be, for example, an evolved node B, eNB.

In order to properly assist the user equipment 30 in transmitting the scheduling request SR to the base station 28, the method may comprise several method steps 701-703. It is noted that the method steps 701-703 may be performed in a slightly different chronological order, and some of them may be performed simultaneously or in a changed or rearranged chronological order. The method may comprise the steps of:

step 701

The factor k to be transmitted to the user equipment 30 is determined so that the user equipment 30 can calculate the scheduling request prohibit timer length.

Step 702

The determined factor k is transmitted to the user equipment 30.

Step 703

The user equipment 30 is scheduled when a scheduling request SR is received from the user equipment 30.

Fig. 8 schematically illustrates an arrangement 800 in a base station 28. The arrangement 800 is configured to perform method steps 701-703. Thus, the base station arrangement 800 is configured to assist the user equipment 30 to transmit a scheduling request SR to the base station 28.

The base station 28 is adapted to serve a user equipment 30. The user equipment 30 is configured to transmit scheduling requests SR to the base station 28 only at certain predetermined scheduling request occasions t0, t1, t2, t3, t 4. The base station 28 and the user equipment 30 are comprised in a wireless communication system 100. According to some embodiments, the wireless communication system 100 may be, for example, an IMT-advanced or LTE radio network, and the base station 28 may be, for example, an evolved node B, eNB.

To perform method steps 701-703, the arrangement 800 comprises a plurality of units, such as for example a determination unit 810. The determining unit 810 is configured to determine a factor k to be transmitted to the user equipment 30 for the user equipment 30 to calculate the scheduling request prohibit timer length. In addition, the arrangement 800 comprises a transmitter 820. The transmitter 820 is configured to transmit the determined factor k to the user equipment 30. Additionally, the arrangement 800 includes a scheduler 38. The scheduler 38 is configured to schedule the user equipment 30 when a scheduling request SR is received from the user equipment 30.

Further, optionally according to some embodiments, the base station arrangement 800 may comprise a receiver 805. Receiver 805 may be configured to receive signals from user equipment 30. Also, according to some embodiments, the arrangement 800 may comprise a scheduling request prohibit timer configuration unit 42.

Optionally, the arrangement 800 further may also include a processor 840. Processor 840 may be represented, for example, by a Central Processing Unit (CPU), processing unit, microprocessor, or other processing logic that may interpret and execute instructions. The processing unit 840 may perform all data processing functions for inputting, outputting, and processing data, including data buffering and device control functions, such as call processing control, user interface control, and so forth.

It is noted that any internal electronics of the base station 28 and/or the base station arrangement 800, which are completely unnecessary for understanding the inventive method according to method steps 701-703, have been omitted from fig. 8 for reasons of simplicity. Further, it is to be noted that some of the described units 38-840 comprised within the arrangement 800 in the base station 28 are considered as separate logical entities, but not necessarily separate physical entities. As just one example, the receiver 805 and the transmitter 820 may be contained or co-arranged within the same physical unit, a transceiver, which may include a transmitter circuit and a receiver circuit, which respectively transmit outgoing radio frequency signals and receive incoming radio frequency signals via an antenna. The radio frequency signals transmitted between the base station 28 and the user equipment 30 may include both traffic and control signals, e.g., paging signals/messages for incoming calls, which may be used to establish and maintain a voice call communication with another party, or to transmit and/or receive data, such as SMS, e-mail or MMS messages, with any remote user equipment.

The inventive mechanism for assisting the user equipment 30 to send the scheduling request SR may be implemented by one or more processors 840 in the base station arrangement 800 depicted in fig. 8, together with computer program code for performing method steps 701-703 of the inventive solution. The program code mentioned above may also be provided as a computer program product, for example in the form of a data carrier carrying computer program code for performing the inventive solution when being loaded into the base station 28. One such carrier may be in the form of a memory stick. However, other data carriers are also possible. The computer program code may also be provided as program code on a server and downloaded to the base station 28 remotely.

When the expression "comprising" is used, it is to be interpreted as non-limiting, i.e. meaning "consisting at least of. The invention is not limited to the preferred embodiments described above. Various alternatives, modifications, and equivalents may be used. Accordingly, the above embodiments are not to be taken as limiting the scope of the invention, which is defined by the appended claims.

Claims (11)

1. Method in a user equipment (30) for transmitting Scheduling Requests (SR) to a base station (28), the base station (28) being adapted to serve the user equipment (30), the user equipment (30) comprising a scheduling request transmission trigger, the user equipment (30) being configured to transmit Scheduling Requests (SR) to the base station (28) only at certain predetermined scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞), the method comprising:

triggering (502) a scheduling request transmission;

transmitting (503) a Scheduling Request (SR) to the base station (28) as a response to the trigger at a next occurring scheduling request opportunity (t0, t1, t2, t3, t4, …, t ∞);

starting (504) a scheduling request prohibit timer (40) comprised in the user equipment (30) when the Scheduling Request (SR) is transmitted to the base station (28) for the first time; and

inhibiting (505) any further scheduling request retransmissions at future scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞) when the scheduling request prohibit timer (40) is running,

wherein the scheduling request prohibit timer (40) is configured to have a scheduling request prohibit timer length equal to the time between two scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞) multiplied by a factor k such that:

the scheduling request prohibit timer length k (t2-t 1).

2. The method of claim 1, further comprising the steps of:

stopping (506) the scheduling request prohibit timer (40) when the Scheduling Request (SR) is cancelled or when the scheduling request prohibit timer (40) expires.

3. The method of any of claims 1 or 2, further comprising the step to be performed before the other steps of:

configuring (501) the scheduling request prohibit timer (40) with a scheduling request prohibit timer length such that the scheduling request prohibit timer (40) expires when the configured scheduling request prohibit timer length has elapsed after the scheduling request prohibit timer (40) has been started.

4. The method according to any of claims 1 or 2, wherein the scheduling request prohibit timer (40) is configured to be a fixed scheduling request prohibit timer length.

5. The method of any of claims 1 or 2, wherein the scheduling request prohibit timer (40) is configured to be equal to a scheduling request prohibit timer length of a time between two scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞) multiplied by a result of a factor k being operated on by a random variable/, such that:

the scheduling request prohibit timer length is (k + l) · (t2-t 1).

6. The method of claim 1, wherein the factor k is received from the base station (28).

7. The method of claim 5, wherein the random variable/, is randomly generated by the user equipment (30).

8. The method of claim 1, wherein the factor k ranges between 0 and infinity such that: k is [0,1, ],

wherein the factor k is transmitted from the base station (28) via radio resource control, RRC, and

wherein the Scheduling Request (SR) is transmitted on a Physical Uplink Control Channel (PUCCH).

9. A user equipment (30) for transmitting Scheduling Requests (SR) to a base station (28), the base station (28) being adapted to serve the user equipment (30), the user equipment (30) being configured to transmit Scheduling Requests (SR) to the base station (28) only at certain predetermined scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞), the user equipment (30) comprising:

a scheduling request transmission trigger (620) configured to trigger a scheduling request transmission;

a transmitter (630) configured to transmit a Scheduling Request (SR) to the base station (28) at a next occurring scheduling request occasion (t0, t1, t2, t3, t4, …, t ∞) as a response to the triggered scheduling request transmission; and

a scheduling request prohibit timer (40) configured to start when the Scheduling Request (SR) is transmitted for the first time and prohibit any further scheduling request retransmissions at future scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞) when the scheduling request prohibit timer (40) is running,

wherein the scheduling request prohibit timer (40) is configured to have a scheduling request prohibit timer length equal to the time between two scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞) multiplied by a factor k such that:

the scheduling request prohibit timer length k (t2-t 1).

10. Method in a base station (28) for assisting a user equipment (30) to transmit a Scheduling Request (SR) to the base station (28), the base station (28) being adapted to serve the user equipment (30), the user equipment (30) being configured to transmit a Scheduling Request (SR) to the base station (28) only at certain predetermined scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞), the method comprising:

determining (701) a factor k to be transmitted to the user equipment (30),

wherein the factor k is transmitted from the base station (28) via radio resource control, RRC, and

wherein the Scheduling Request (SR) is transmitted on a physical uplink control channel, PUCCH, enabling the user equipment (30) to calculate a scheduling request prohibit timer length;

transmitting (702) the determined factor k to the user equipment (30); and

scheduling (703) the user equipment (30) when a Scheduling Request (SR) is received from the user equipment (30).

11. A base station (28) for assisting a user equipment (30) to transmit a Scheduling Request (SR) to the base station (28), the base station (28) being adapted to serve the user equipment (30), the user equipment (30) being configured to transmit a Scheduling Request (SR) to the base station (28) only at certain predetermined scheduling request occasions (t0, t1, t2, t3, t4, …, t ∞), the base station (28) comprising:

a determining unit (810) configured to determine a factor k to be transmitted to the user equipment (30) for the user equipment (30) to calculate a scheduling request prohibit timer length;

a transmitter (820) configured to transmit the determined factor k to the user equipment (30),

wherein the factor k is transmitted from the base station (28) via radio resource control, RRC, and

wherein the Scheduling Request (SR) is transmitted on a Physical Uplink Control Channel (PUCCH); and

a scheduler (830) configured to schedule the user equipment (30) when a Scheduling Request (SR) is received from the user equipment (30).