Uplink Maximum Bit Rate Control Field of the Technology
The present invention relates to Uplink Maximum Bit Rate control in a radio packet communication network.
Background of the Invention
More particularly, the present invention relates to Maximum Bit Rate (MBR) and Aggregated Maximum Bit Rate (AMBR) for radio bearers in a wireless communication system, such as 3GPP Long Term Evolution (LTE), Universal Mobile Telecommunication System (UMTS), or the like. In modern Quality of Service (QoS) aware packet based networks, data (and signalling) of different QoS classes can have different probabilities of data loss, have different delay characteristics and/or experience different throughputs.
Radio bearers are the service provided by layer 2 of the Open Systems Interconnection (OSI) model for transfer of user data between a User Equipment (UE) and a UMTS Terrestrial Radio Access Network (UTRAN) in the Wideband Code Division Multiple Access (WCDMA) 3G technology.
Data belonging to one QoS class can be transported over the same radio bearer. Data belonging to different QoS classes are transported over different radio bearers.
The terms Radio Access Bearer (RAB) and System Architecture Evolution (SAE) bearer are in UMTS used for identifying the service which the AS (Access Stratum) provides to the NAS (Non Access Stratum), for transfer of user data between the UE and the Core Network (CN). The present invention relates to the wireless interface. Thus, hereafter the transport over radio bearers will only be further discussed.
In earlier 3GPP wireless networks, enforcement of throughput limitations, MBR limitations, has been performed in the CN. The reason for such limits can be related to business or subscription. For instance, for a specific subscription a specific MBR is allowable. For high throughput radio interfaces, such as the one in LTE, the achievable radio throughput might be significantly higher than the allowable MBR. Thus, in order to save radio resources, it is suitable to perform the MBR enforcement for Uplink (UL) in the UE, which is also the current working assumption for LTE. Different Radio bearers may have different MBRs (or no MBR), and also groups of radio bearers might be subject to an AMBR restriction. Subsequently in this specification, the term MBR is used for both MBR and AMBR, when not further specified.
Further, it is in this specification assumed that a UE cannot send data in the UL whenever he wants to. Instead, the UE has to adhere to a Medium Access Control (MAC) protocol in order to gain access to uplink transmission resources.
For 3GPP WCDMA enhanced uplink (E-DCH), there is such a MAC protocol, working in accordance with the following:
1. If the UE has (more) data to transmit, it needs to transmit scheduling information to the network, indicating the amount of stored data, and the maximal transmission capacity of the UE in the current radio conditions. This scheduling information may be sent alone, or piggybacked on a data transmission in a MAC protocol header of a packet.
2. The network then allocates radio resources to the UE, and signals this resource allocation grant to the UE.
3. The UE can then use these allocated resources to transmit the data.
WCDMA Layer 1 UL basically allows the UE to transmit scheduling information at any point in time, the only side effect being the increased interference caused by this transmission. For 3GPP LTE, it is assumed that the same steps 1, 2 and 3 above shall be used.
However, for LTE the situation is somewhat different. For LTE, no spontaneous transmission is possible (except on the random access channel). In LTE UL, either the UE has to do a random access request first, to get enough UL transmission resources to be able to send scheduling information or it has to have some kind of periodic UL resource already allocated, to be able to indicate that it has data to send. Thus, for LTE there will most probably be an additional step before step 1 above. Furthermore, there are other differences between LTE and WCDMA:
-The scheduling information in LTE might be more detailed, e.g. it might include information on how much data that is buffered for each priority class, i.e. for each radio bearer. This information is needed for fair scheduling if there is congestion and if there are several UEs transmitting on several priority classes.
This part of the scheduling information is for LTE called Buffer Status Report (BSR).
-The nature of the resource allocation grant differs in WCDMA and LTE. In WCDMA, the resource allocation grant relates to allowed transmit power. For LTE, a set of subcarrier frequencies and time-slots need to be indicated in the resource allocation grant.
However, it can be noted that for both WCDMA and LTE, the resource allocation grant is per UE, and the three basic steps 1, 2 and 3 above constitute the assumption for how to transmit data in LTE UL. To control transmission rate, the data source (the sender) always has to be instructed to reduce its transmission rate. The principle for how this is done is different in different protocols. Rate control is typically an end-end function, usually part of an end-end protocol, whereas the reasons for reducing the rate are present in lower protocol layers, e.g. in protocols for network or link level transmissions, which makes rate control rather complicated.
Some protocol stacks assumes delivery of explicit congestion notifications from lower to higher layers, but often, e.g. in the Transmission Control Protocol/Internet Protocol (TCP/IP) arena, the TCP transport protocol and User Datagram Protocol (UDP) applications react to data transmission delay and data loss. The TCP transmitter maintains timers and Acknowledgement (ACK) status of transmitted protocol data units. When TCP considers that a PDU is lost, it reduces its window size (allowed burst size) to half the size, effectively reducing its rate and buffering requirements in intermediate nodes. For UDP applications, there is no general requirement to do rate control, but many applications, especially high-rate applications, e.g. video, or applications tailored for wireless voice, such as Adaptive Multi-Rate (AMR), can perform rate control. Generally, for UDP applications, the receiver measures delay and dropped packets, and regularly sends a transmission report back to the sender to allow it to change its rate, also there may be possibilities for the receiver to directly request certain rates. UDP applications that have rate control and that reduce its rate based on data loss, and maybe also based on increased delay, are called TCP-friendly applications.
As stated above, a specific business or subscription relates to a specific allowable UL MBR, and this UL MBR should be enforced in the UE by limiting the transmission rate by the use of packet dropping or delaying packets. A problem relating to the MBR limitation is how to know when to apply MBR enforcement, e.g. packet dropping or delaying, on the transmitted data. Following earlier 3GPP principles for determining what and how much to send, such decisions would be taken at the moment of transmission, i.e. after the UE has received a resource allocation grant from the network. This principle is probably also the most accurate one, since MBR then can be enforced based on the actual transmitted data.
If MBR would instead be enforced on internal stack transmissions, it would be quite inaccurate. Burst sizes internally in the stack would mainly depend on the applications, and these burst sizes might be quite different from the radio transmission burst sizes to be transmitted. Also, the UE does generally not know the congestion status of the wireless interface and the UE can usually not predict it either. Thus, the decision to drop a certain packet might be premature if taken at some other time than at the time of transmission, since the packet anyway might be delayed due to congestion in the wireless interface.
Figure 1 shows a flow diagram for a prior art MBR limitation method implemented in a UE. In a first step of the method, packets arrive at the UE. These packets are added to the transmission buffer. In a second step of the method, the UE sends a Buffer Status Report (BSR) to a network node being able to allocate transmission resources. This BSR includes data volume information relating to all packets in the transmission buffer. The network node then allocates transmission resources corresponding to the request to the UE, and informs the UE of this in a response, granting the UE to use these resources. In a third step, the UE receives this grant, relating to transmission resources for all packets in the buffer. In a fourth step, if necessary, the UE enforces MBR limitation by dropping packets until the bit rate is less than the MBR limit.
A problem of prior art MBR enforcement solutions is the "grant loss" problem.
This problem occurs when the UE reports in the buffer status report that it has a specific number of bytes in its transmission buffer, which typically would result in a response from the network including a resource allocation grant allowing the UE to transmit this specific number of bytes. Then, if the UE applies the MBR enforcement at the point of transmission, it is probable that the UE will drop packets in order to not exceed the MBR limitation. Thus, the UE would in this situation drop packets for which it already has requested and been granted transmission resources. The whole resource allocation grant would then not be utilised, i.e. a waste of radio transmission resources occurs.
Summary of the Invention
An embodiment of the present invention provides a method for UL MBR control that solves the above stated problem.
A method for UL MBR control is provided to waste less transmission resources than the UL MBR enforcement known in the prior art.
According to one aspect of the invention a method, in which a UE in the network is provided, wherein including: - evaluating each packet being added to a transmission buffer based on a MBR level, considering each evaluated packet as being either a conformant or a non- conformant packet, wherein a packet is considered to be non-conformant if it, at the time for the evaluation, is intended to be dropped or delayed,
- creating a Buffer Status Report (BSR), including data volume information relating only to packets in the transmission buffer being considered as conformant packets, and
- transmitting the BSR to a node performing Medium Access Control (MAC) in the network. According to the other aspect of the present invention, a computer program executing the method and a computer program product including the computer program in its computer readable medium are provided.
According to another aspect of the present invention a UE is provided for performing the following steps:
- evaluating each packet being added to a transmission buffer based on a MBR level, considering each evaluated packet as being either a conformant or a non- conformant packet, wherein a packet is considered to be non-conformant if it, at the time for the evaluation, is intended to be dropped or delayed, - creating a Buffer Status Report (BSR), including data volume information relating only to packets in the transmission buffer being considered as conformant packets, and
- transmitting the BSR to a node performing Medium Access Control (MAC) in the network. According to another aspect of the present invention, a communication system is operable for providing uplink Maximum Bit Rate (MBR) control. The system includes at least one UE operable for evaluating whether each packet being added to a transmission buffer is intended to be transmitted or not on a MBR lever, and transmitting a Buffer Status Report (BSR)to a node, said BSR including data volume information relating only packets in the transmission buffer which is intended to be transmitted; and at least one node operable for receiving said BSR and responds to said UE by indicating which resources that have been allocated for said UE.
In the embodiment of the present invention, data volume information is only included in the Buffer Status Report for packets that are considered as conformant packets. Thus, data volume information is not reported for packets in the buffer are not intended to be transmitted. This has the advantage that grant loss can be avoided, since transmission resources are only requested for packets really intended for transmission.
Further, the UL MBR control according to the present invention also has the advantage that dropping or delaying of data can be performed at the moment of transmission, resulting in an accurate MBR limitation. According to an embodiment of the present invention, packets being added to a transmission buffer are evaluated and it is decided whether the packets should be intended to be dropped or not. If there is a risk for exceeding MBR, the packets are considered as being non-conformant packets, and if there is no risk for exceeding MBR, they are considered as being conformant packets.
According to an embodiment of the present invention, packets having been considered as non-conformant may be re-considered as being conformant in some cases.
This labelling of packets as being conformant and non-conformant has the advantage that a sufficient amount of transmission resources will be requested by the UE and also that the granted transmission resources are efficiently utilised.
After a sufficient amount of resources have been granted, it is up to the dropping mechanism to decide which packets to eventually drop, based on the transmission resource allocation grant received from a node performing Medium Access Control (MAC) in the network and on the labelling of the packets in the buffer as being conformant or non-conformant.
According to an embodiment of the present invention, the dropping mechanism takes into account the effect dropping or delaying of a specific packet will have on the application, for which the packet is carrying data. For example, if the application is a rate adaptive application, a packet in the head of the buffer is dropped or delayed in order to as fast as possible signal to the application that it has to lower its rate. This has the advantage that rate adaptation of the application is quicker.
According to an embodiment of the present invention, evaluation and dropping or delaying of packets takes into account priorities set for the packets. This has the advantage that the UL MBR control according to this embodiment of the invention also is priority aware. Thus, if possible, packets having lower priority are dropped before packets having high priority. By this, important packets, such as certain QoS class packets or packets for certain important applications will have a low probability of being dropped or delayed. Detailed exemplary embodiments and advantages of the UL MBR control according to the invention will now be described with reference to the appended drawings illustrating some preferred embodiments. Brief Description of the Drawings
Figure 1 shows a flow diagram for a prior art MBR limitation method implemented in a UE.
Figure 2 shows a flow diagram for a MBR limitation method according to an embodiment of the present invention implemented in a UE.
Detailed Description of the Invention
According to an embodiment of the present invention, only packets containing data that is not intended to be dropped or delayed, i.e. conformant data, in the UE transmission buffers shall be reported in the buffer status report. This has the advantage that grant loss can be avoided, since transmission resources are only requested for packets really intended for transmission.
The transmission resource requesting principle according to the present invention can be combined with accurate MBR enforcement, i.e. dropping or delaying of data, since the dropping or delaying of data can be performed at the moment of transmission. Thereby an accurate MBR limitation is achievable by the present invention.
Further, the principle of the present invention may be combined with other functions needed for data dropping, such as Random Early Discard (RED) implementation, for graceful rate control, and QoS-aware intelligent Random Early Discard (RED), knowing which flows that are rate adaptive/non-rate adaptive.
Further, in cases of congestion and long scheduling delays, the amount of data that is allowed to be transmitted might be underestimated in the buffer status report
(due to the delay between buffer status report and resource allocation grant), which might lead to a need of additional scheduling occasions to transmit a certain amount of data.
This problem is, according to an embodiment of the present invention, solved by extending the information in the buffer status report to also include more advanced indications, indicating that there is more data available, for a certain Radio Bearer
(RB), which might be MBR conformant data or MBR non-conformant data, depending on the time delay until the resource allocation grant. According to the present invention, packets being added to a transmission buffer are evaluated and it is decided whether the packets should be intended to be dropped or not. Packets intended to be dropped are considered as being non-conformant packets and packets not intended to be dropped are considered as being conformant packets.
The evaluation mainly checks if the packets added to the transmission buffer will make the UE exceeding its MBR limitation. If there is a risk for exceeding MBR, the packets are considered as being non-conformant packets, and if there is no risk for exceeding MBR, they are considered as being conformant packets. Generally, packets arriving at a too high rate, exceeding a rate corresponding to the output MBR, will be considered as being non-conformant. Detection of a too high arriving rate may be performed in a number of ways, for example by the use of a token bucket model detection, or any other suitable mechanism known by a skilled person for performing rate detection. The token bucket model is described more in detail below.
According to an embodiment of the present invention, packets having been considered as non-conformant may be re-considered as being conformant in some cases. Such cases include radio congestion problems, situations where packets are dropped for other reasons than MBR enforcement, a situation where a resource allocation grant from a network node is delayed, or the like. In such cases, reconsidering of packets from non-conformant to conformant may be advantageous since otherwise the UE could cause excessive dropping of packets.
Thus, according to the present invention, after packets added to the transmission buffer have been evaluated, each packet in the transmission buffer is labelled as being considered as a conformant packet or a non-conformant packet. Transmission resources are then requested for conformant packets. After this, it is up to the dropping mechanism to decide which packets to eventually drop, based on the transmission resource allocation grant received from a node performing MAC and on the labelling of the packets in the buffer as being conformant or non-conformant. Figure 2 shows a flow diagram for a MBR limitation method according to an embodiment of the present invention implemented in a UE. In a first step of the method, packets arrive at the UE. In a second step, these arriving packets are evaluated, deciding whether each packet is intended to be transmitted or not. If it is intended to be transmitted, it is considered as being a conformant packet and if it is not intended to be transmitted, it is considered as being a non-conformant packet. The packets are then added to the transmission buffer. In a third step of the method, the UE sends a BSR to a network node being able to allocate transmission resources. This BSR includes data volume information relating only to packets in the transmission buffer considered as being conformant packets. The network node then allocates transmission resources to the UE corresponding to the request, and informs the UE of this in a response, granting the UE to use these resources. In a fourth step, the UE receives this grant, relating to transmission resources for the conformant packets in the buffer. In a fifth step, if necessary, the UE enforces MBR limitation by corresponding processing, such as dropping packets or delaying packets or any other actions, until the bit rate is less than the MBR limit. This dropping or delaying in this embodiment is performed by choosing packets to drop or delay, based on the received grant and on the evaluation of the packets, i.e. if packets are considered conformant or non-conformant.
Thus, the MBR limiting method according to the present invention has the advantage that transmission resource waste is minimised, since transmission resources only are requested for packets really intended for transmission. Dropping or delaying data (packets), after transmission resource requesting and granting, in accordance with the present invention, can be performed in a number of ways. Hereafter will some examples of dropping of data be described. As is clear to a skilled person, there are numerous ways for dropping of data, which all may be combined with the transmission resource request and allocation according to the present invention. If data is delayed instead of dropped, corresponding mechanisms are used as for dropping, with the difference, of course, that packets are delayed instead of deleted.
IP network equipments (routers) are expected to drop packets when congestion occurs to trigger the end-to-end rate control mechanisms of TCP and TCP-friendly applications. When severe congestion occurs it could be assumed that data buffers are full and all/many incoming packets have to be discarded. In order to allow graceful rate reduction of various flows, usually a mechanism called Random Early Discard (RED) is used. The idea of the RED mechanism is that before congestion is severe, a few packets are pseudo-randomly selected and dropped. These dropped packets then serve as a signal to the rate adaptive applications, for which packets are dropped, to reduce its transmission rate. Thus, the dropping of packets also signals to the application that its bit rate is too high. This type of signalling is very useful for such rate adaptive applications.
According to an embodiment of the present invention, the UE is informed that the application is a rate adaptive application by the signalling that configures a radio bearer used for the application or from internal packet filters. The RED mechanism offers a smooth rate reduction, reducing the risk of congestion. However, packets might need to be retransmitted, so if dropping is done carelessly, retransmissions might cause the applications to increase the transmission rate instead of reducing it.
According to an embodiment of the present invention, when applying RED, packets are not dropped at the tail of queues but instead at the head. The purpose of this is to make the dropped packet detection as fast as possible in the end-to-end packet layer. Thus, by dropping packets being at the head of the transmission buffer, a faster rate adaptation in the rate adaptive applications is possible.
The rate control discussed above is described in the context of a network. Internally, in a protocol stack, there is also a need for rate control, as higher protocol layers may generate more data than can be transmitted through the lower protocol layers. Internally, in a protocol stack, this can be resolved by having explicit flow control mechanisms between protocol layers, i.e. there would be rate control possibilities in the transmission Application Programming Interface (API) between the protocol stack and the applications. This is generally the case for TCP, but not for UDP.
Further, there are other rate control mechanisms that may implemented in the present invention. The token bucket model is such a mechanism usable for rate control and traffic shaping. The token bucket model can be used for various purposes. When used for traffic shaping, the token bucket mechanism is a simple, but effective, rule for transmission. A token (usually) corresponds to a certain amount of data. Each time such an amount of data is transmitted a corresponding token in the token bucket is consumed. If multiple such amounts of data are transmitted at the same time, multiple tokens are consumed. If there are not enough tokens in the bucket, the corresponding packet is not allowed to be transmitted. The maximum amount of data that can be transmitted at one time, the max burst size, is the amount of data that corresponds to a full bucket of tokens. The token bucket is continuously (re-)filled with tokens at a certain steady token rate, which corresponds to the maximum average data rate that is allowed, MBR.
When used for traffic shaping according to an embodiment of the present invention, the token bucket model is used for determining which packets to be considered as conformant and non-conformant packets, typically resulting in that the non-conformant packets later are dropped or delayed (buffered). This has the advantage that a controlled dropping not resulting in grant loss may be performed. Alternatively, for other purposes, non-conformant packets could just be measured or maybe considered for subsequent QoS differentiation. In order to enforce UL MBR in the case of UDP applications and in the case when a UE is connected to an application device by a cable, typically to a laptop or the like, i.e. a situation where the wireless protocol stack and the application protocol TCP/IP stack are disjoint, we here make the assumption that we can not rely on internal protocol stack flow control for rate control. Instead we assume that packet dropping or delaying are the only ways to achieve rate control, except for some certain applications there might be other ways.
According to an embodiment of the present invention, in order to enforce MBR, a token bucket model is used for determining if a packet is to be considered as conformant or non-conformant. To implement RED behaviour for graceful rate control, the token bucket model has two token buckets, or one token bucket with an intermediate threshold. Thus, the token bucket model comprises:
1. Token bucket no. 1 or threshold no. 1: Random Drop.
-This is the token bucket or the threshold that triggers RED. The rate adaptation is achieved by the random drop threshold when a few packets randomly are selected and dropped. The main purpose for this is to drop as few packets as possible to signal to the application that it should adjust its uplink transmission bit rate, thereby lowering the bite rate. 2. Token bucket no. 2 or threshold no. 2: Bulk Discard (bucket empty).
-During the bulk discarding, the bucket is empty and all of the non- conformant packets are dropped.
Thus, the token bucket model is used for enforcing MBR control in an easily implemented fashion, which is advantageous. The token bucket model for dropping packets can also in a non-complex way be implemented in the present invention.
According to an embodiment of the present invention, the UE is informed of parameters needed by the UE to configure the token bucket model by the signalling used to configure a radio bearer used for conveying information for an application. According to an embodiment of the present invention, rate control is then performed such that packets belonging to rate adaptive flows have higher drop probability than the non-rate adaptive ones. This results in that packets carrying data for a rate adaptive application are dropped more often than packets carrying data for applications not being rate adaptive, which is advantageous because a rate adaptive application can adjust its bit rate when it realises that a packet has been dropped. Applications not being rate adaptive can not mitigate the situation even if it realises that its packets are being dropped because of MBR limitations.
As stated above, a group of RBs can also have a common AMBR. Different RBs sharing such an AMBR can also have different drop probabilities, i.e. different priorities assigned to its packets, since the bit rates may be different for different RBs.
According to an embodiment of the present invention, these different drop probabilities can also relate to the rate adaptation possibilities of the applications for which the RBs are carrying data.
Further, packets belonging to different QoS classes also have different priorities assigned to them.
The relation between application rate adaptation possibilities and drop probabilities described above is advantageous since it maximizes the likelihood that packets are dropped from flows that actually can respond to the packet drop, and not other flows. Thus, this minimizes the amount of lost data due to rate control. In an embodiment of the invention, different priorities assigned to different packets are also used as a basis for evaluating the packets. In the step of evaluating packets as being conformant or non-conformant, priority is here a parameter for the decision. For example, if a high priority packet causes a risk for MBR to be exceeded, instead of considering this high priority packet as non-conformant, a lower priority packet is considered as non-conformant. In particular, the choice of considering the lower priority packet as non-conformant is advantageous if the lower priority packet has not been accounted for in a previously sent BSR. Otherwise this could infer a grant loss.
According to an embodiment of the present invention, data volume information relating to non-conformant packets should not be part of the Buffer Status Report. Dropping of packets may then be performed in a number of ways, for instance by having the following features:
1. Non-conformant packets are subject to RED dropping. Also, a packet elsewhere in the queue can be selected for drop, e.g. at the head of the queue, in order to inform an adaptive application at an early stage that its packets are being dropped. Another packet elsewhere in the queue should only be selected to be dropped if the size of the selected packet is less than or equal to the size of all of the packets being considered as being non-conformant. However, if a packet having a size bigger than the sum size of the non-conformant packets instead would be chosen to be dropped, this would lead to excessive packet loss. By choosing other packets than the ones being considered as non-conformant packets by the packet evaluation step, some packets might need to be reconsidered as being non-conformant.
2. When a drop decision has been taken, and other packet(s) than the non- conformant one(s) that caused the decision, or just a subset of the packets, are dropped, the remaining non-conformant packets that caused the drop decision are re-considered as being conformant packets. This compensates the bucket for the dropping packet rate instead of consuming the tokens.
3. Drop decisions need to be re-evaluated at least every time the UE is scheduled transmission resources. Thus, according to an embodiment of the present invention, both non-conformant and conformant packets can be chosen to be dropped or delayed. The choice is based on transmission resource grant, the evaluation of the packets (conformant/non- conformant) and on the effect dropping or delaying packets will have on the application, for which the packet conveys data.
A conformant packet is only chosen if there is a corresponding amount of non- conformant packets in the transmission buffer, in order to avoid further packet loss. Also, if a conformant packet is chosen, non-conformant packets of a total size corresponding to the chosen conformant packet are being re-considered as being conformant packets. This has the advantage that the resources requested by the UE thereby will be enough to carry the packets not being dropped or delayed, since the network node probably will grant transmission resources for all conformant packets. Thus, transmission resources are not wasted.
According to an embodiment of the invention, the BSR also includes, information, such as a flag, indicating that there is at least one non-conformant packet present in the transmission buffer, if this is the case. However, this flag only indicates that there is at least one non-conformant packet present in the buffer, it does not indicate the size of these packets or request transmission resources for these packets.
The different steps of the method of the invention described above can be combined or performed in any suitable order. A condition for this is that the requirements of a step, to be used in conjunction with another step of the method of the invention, in terms of available information and the like must be fulfilled. The method of the invention can be performed by the use of a computer program, having code means, which when run in a computer causes the computer to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may consist of essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.
The present invention also includes a UE for implementing the methods of the invention. Thus, the UE of the present invention is arranged to evaluate each packet being added to a transmission buffer based on a MBR level, considering each evaluated packet as being either a conformant or a non-conformant packet. In this evaluation a packet is considered to be non-conformant if it, at the time for the evaluation, is intended to be dropped or delayed. The UE is further arranged to create a Buffer Status Report (BSR), including data volume information relating only to packets in the transmission buffer being considered as conformant packets, and to transmit this BSR to a node performing Medium Access Control (MAC).
This UE can be arranged for, by being adapted to include means for, performing any of the steps of the method of the invention. A trivial requirement is of course that such a step does involve the UE.
Another embodiment of the present invention provides a communication system which is operable for providing uplink Maximum Bit Rate (MBR) control. The system includes at least one UE and at least one node. The at least one UE and node can perform MBR control as described above. The at least one UE is operable for evaluating whether each packet being added to a transmission buffer is intended to be transmitted or not on a MBR lever, and transmitting a Buffer Status Report (BSR)to a node, said BSR including data volume information relating only packets in the transmission buffer which is intended to be transmitted. The least one node operable for receiving said BSR and responds to said UE by indicating which resources that have been allocated for said UE. Said UE is operable for dropping or delaying at least one packet based on the resources that have been allocated for said UE and on the evaluation of the packets in the transmission buffer. Therefore, the transmission resources of the system are efficiently utilised. It can be understood that the UL MBR control according to the invention may be modified by those skilled in the art, as compared to the exemplary embodiments described above.