Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L49/00—Packet switching elements
  • H04L49/90—Buffering arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q11/00—Selecting arrangements for multiplex systems
  • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
  • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
  • H04Q11/0478—Provisions for broadband connections
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/50—Allocation or scheduling criteria for wireless resources
  • H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
  • H04W72/543—Allocation or scheduling criteria for wireless resources based on quality criteria based on requested quality, e.g. QoS
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5629—Admission control
  • H04L2012/5631—Resource management and allocation
  • H04L2012/5632—Bandwidth allocation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/54—Store-and-forward switching systems 
  • H04L12/56—Packet switching systems
  • H04L12/5601—Transfer mode dependent, e.g. ATM
  • H04L2012/5638—Services, e.g. multimedia, GOS, QOS
  • H04L2012/5646—Cell characteristics, e.g. loss, delay, jitter, sequence integrity
  • H04L2012/5652—Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
  • H04L2012/5653—Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly using the ATM adaptation layer [AAL]
  • H04L2012/5656—Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly using the ATM adaptation layer [AAL] using the AAL2

Definitions

• the present invention relates in general to the field of communications systems, and in particular, by way of example but not limitation, to scheduling packets of data/informational flows having differing priority levels in a communications system.
• wireless networks Access to and use of wireless networks is becoming increasingly important and popular for business, social, and recreational purposes. Users of wireless networks now rely on them for both voice and data communications. Furthermore, an ever increasing number of users demand both an increasing array of services and capabilities as well as greater bandwidth for activities such as Internet surfing. To address and meet the demands for new services and greater bandwidth, the wireless communications industry constantly strives to improve the number of services and the throughput of their wireless networks. Expanding and improving the infrastructure necessary to provide additional services and higher bandwidth is an expensive and manpower-intensive undertaking. Moreover, high-bandwidth data streams will eventually be demanded by consumers to support features such as real-time audiovisual downloads and live audio-visual communication between two or more people.
• next generation wireless system(s) instead of attempting to upgrade existing system(s).
• the wireless communications industry intends to continue to improve the capabilities of the technology upon which it relies and that it makes available to its customers by deploying next generation system(s).
• Protocols for a next-generation standard that is designed to meet the developing needs of wireless customers is being standardized by the 3 rd Generation Partnership Project (3GPP).
• 3GPP 3 rd Generation Partnership Project
• the set of protocols is known collectively as the Universal Mobile Telecommunications
• the network 100 includes a core network 120 and a UMTS Terrestrial Radio Access Network (UTRAN) 130.
• the UTRAN 130 is composed of, at least partially, a number of Radio Network Controllers (RNCs) 140, each of which may be coupled to one or more neighboring Node Bs 150.
• RNCs Radio Network Controllers
• Each Node B 150 is responsible for a given geographical cell and the controlling RNC 140 is responsible for routing user and signaling data between that Node B 150 and the core network 120. All of the RNCs 140 may be directly or indirectly coupled to one another.
• the UMTS network 100 also includes multiple user equipments (UEs) 110.
• UE may include, for example, mobile stations, mobile terminals, laptops/personal digital assistants (PDAs) with wireless links, etc.
• PDAs personal digital assistants
• data transmissions and/or access requests compete for bandwidth based on first come, first served and/or random paradigms.
• Each mobile station, and its associated transmissions typically acquire access to a network using some type of request (e.g., a message) prior to establishing a connection.
• the mobile station receives a predetermined transmission bandwidth that is usually mandated by the air interface requirements of the relevant system.
• transmission bandwidth is variable, more flexible, and somewhat separated from the physical channel maximum mandated by the air interface requirements of UMTS.
• QoS quality of service
• a Medium Access Control (MAC) layer schedules packet transmission of various data flows to meet stipulated criteria, including permitted transport format combinations (TFCs) from a TFC set (TFCS).
• TFCs transport format combinations
• TFCS TFC set
• WFQ weighted fair queuing
• QoS class transport block set size
• TBSS transport block set size
• QoS transport format combinations
• second embodiment(s) memory requirements are reduced by selecting a TFC based on guaranteed rate transmission rates, QoS class, TBSS, and queue fill levels, without accommodating backlogs corresponding to previously unsatisfied requirements.
• a scheduling method for providing bandwidth to entities in a communications system includes the steps of: calculating a first transfer rate for multiple flows; calculating a second transfer rate for the multiple flows; ascertaining a quality of service (QoS) for each flow of the multiple flows; and assigning bandwidth to each flow of the multiple flows responsive to the first transfer rate, the second transfer rate, and the QoS for each flow of the multiple flows.
• the first transfer rate may correspond to a guaranteed rate transfer rate
• the second transfer rate may correspond to a weighted fair queuing (WFQ) transfer rate.
• WFQ weighted fair queuing
• the first and second transfer rates may correspond to aggregated transfer rates over the multiple flows.
• a scheduling method for providing bandwidth to entities in a communications system includes the steps of: ascertaining a quality of service (QoS) class that is associated with each channel of multiple channels; ascertaining a guaranteed rate transmission rate for each channel; ascertaining a queue fill level of a queue that corresponds to each channel; calculating a first score for each channel responsive to the QoS class, the guaranteed rate transmission rate, and the queue fill level.
• QoS quality of service
• an additional step of calculating a second score for each channel responsive to the guaranteed rate transmission rate and the queue fill level is included.
• FIG. 1 illustrates an exemplary wireless communications system with which the present invention may be advantageously employed
• FIG. 2 illustrates a protocol model for an exemplary next-generation system with which the present invention may be advantageously employed
• FIG. 3 illustrates a view of an exemplary second layer architecture of an exemplary next-generation system in accordance with the present invention
• FIG. 4 illustrates an exemplary method in flowchart form for allocating bandwidth resources to data flow streams between entities in the exemplary second layer architecture of FIG. 3;
• FIG. 5 illustrates an exemplary environment for scheduling data flows in accordance with the present invention
• FIG. 6 illustrates an exemplary method in flowchart form for scheduling data flows in accordance with the present invention
• FIG. 7 illustrates another view of the exemplary second layer architecture of an exemplary next-generation system in accordance with the present invention
• FIG. 8 illustrates another exemplary method in flowchart form for scheduling data flows in accordance with the present invention.
• FIGS . 1-8 of the drawings like numerals being used for like and corresponding parts of the various drawings.
• Aspects of the UMTS are used to describe a preferred embodiment of the present invention.
• the principles of the present invention are applicable to other wireless communication standards (or systems), especially those in which communication is packet-based.
• FIG. 2 a protocol model for an exemplary next-generation system with which the present invention may be advantageously employed is illustrated generally at 200.
• the "Uu” indicates the interface between UTRAN 130 and the UE 110
• “Iub” indicates the interface between the RNC 140 and a Node B 150 (where "Node B” is a generalization of, for example, a Base
• RABs Radio Access Bearers
• a UE 110 is allocated one or more RABs, each of which is capable of carrying a flow of user or signaling data.
• RABs are mapped onto respective logical channels.
• MAC Media Access Control
• a set of logical channels is mapped in turn onto a transport channel, of which there are two types: a "common” transport channel which is shared by different UEs 110 and a “dedicated” transport channel which is allocated to a single UE 110 (thus leading to the terms “MAC-c" and "MAC-d”).
• FACH One type of common channel is the FACH.
• a basic characteristic of a FACH is that it is possible to send one or more fixed size packets per transmission time interval (e.g., 10, 20, 40, or 80 ms).
• Several transport channels e.g., FACHs
• S-CCPCH Secondary Common Control Physical CHannel
• a UE 110 registers with an RNC 140 via a Node B 150, that RNC 140 acts at least initially as both the serving and the controlling RNC 140 for the UE 110.
• the serving RNC 140 may subsequently differ from the controlling RNC 140 in a UMTS network 100, but the presence or absence of this condition is not particularly relevant here.
• the RNC 140 both controls the air interface radio resources and terminates the layer 3 intelligence (e.g., the Radio Resource Control (RRC) protocol), thus routing data associated with the UE 110 directly to and from the core network
• RRC Radio Resource Control
• the MAC-c entity in the RNC 140 transfers MAC- c Packet Data Units (PDUs) to the peer MAC-c entity at the UE 110 using the services of the FACH Frame Protocol (FACH FP) entity between the RNC 140 and the Node B 150.
• the FACH FP entity adds header information to the MAC-c PDUs to form
• FACH FP PDUs which are transported to the Node B 150 over an AAL2 (or other transport mechanism) connection.
• An interworking function at the Node B 150 interworks the FACH frame received by the FACH FP entity into the PHY entity.
• an important task of the MAC-c entity is the scheduling of packets (MAC PDUs) for transmission over the air interface. If it were the case that all packets received by the MAC-c entity were of equal priority (and of the same size), then scheduling would be a simple matter of queuing the received packets and sending them on a first come first served basis (e.g., first-in, first-out (FIFO)).
• FIFO first-in, first-out
• UMTS defines a framework in which different Quality of Services (QoSs) maybe assigned to different RABs.
• Packets corresponding to a RAB that has been allocated a high QoS should be transmitted over the air interface at a high priority whilst packets corresponding to a RAB that has been allocated a low QoS should be transmitted over the air interface at a lower priority.
• Priorities maybe determined at the MAC entity (e.g., MAC-c or MAC-d) on the basis of RAB parameters.
• UMTS deals with the question of priority by providing at the controlling RNC 140 a set of queues for each FACH.
• the queues may be associated with respective priority levels.
• An algorithm which is defined for selecting packets from the queues in such a way that packets in the higher priority queues are (on average) dealt with more quickly than packets in the lower priority queues, is implemented. The nature of this algorithm is complicated by the fact that the FACHs that are sent on the same physical channel are not independent of one another. More particularly, a set of Transport Format Combinations (TFCs) is defined for each S-CCPCH, where each TFC includes a transmission time interval, a packet size, and a total transmission size (indicating the number of packets in the transmission) for each FACH. The algorithm should select for the FACHs a TFC which matches one of those present in the TFC set in accordance with UMTS protocols.
• TFCs Transport Format Combinations
• a packet received at the controlling RNC 140 is placed in a queue (for transmission on a FACH), where the queue corresponds to the priority level attached to the packet as well as to the size of the packet.
• the FACH is mapped onto a S-CCPCH at a Node B 150 or other corresponding node of the UTRAN 130.
• the packets for transmission on the FACH are associated with either a Dedicated Control CHannel (DCCH) or to a Dedicated Traffic CHannel (DTCH).
• DCCH Dedicated Control CHannel
• DTCH Dedicated Traffic CHannel
• each FACH is arranged to carry only one size of packets. However, this is not necessary, and it may be that the packet size that can be carried by a given FACH varies from one transmission time interval to another.
• the UE 110 may communicate with the core network 120 of the UMTS system 100 via separate serving and controlling (or drift)
• RNCs 140 within the UTRAN 130 e.g., when the UE 110 moves from an area covered by the original serving RNC 140 into a new area covered by a controlling/drift RNC 140 (not specifically shown). Signaling and user data packets destined for the
• the UE 110 are received at the MAC-d entity of the serving RNC 140 from the core network 120 and are "mapped" onto logical channels, namely a Dedicated Control CHannel (DCCH) and a Dedicated traffic CHannel (DTCH), for example.
• the MAC- d entity constructs MAC Service Data Units (SDUs), which include a payload section containing logical channel data and a MAC header containing, inter alia, a logical channel identifier.
• SDUs MAC Service Data Units
• the MAC-d entity passes the MAC SDUs to the FACH FP entity.
• This FACH FP entity adds a further FACH FP header to each MAC SDU, where the FACH FP header includes a priority level that has been allocated to the MAC SDU by an RRC entity.
• the RRC is notified of available priority levels, together with an identification of one or more accepted packet sizes for each priority level, following the entry of a UE 110 into the coverage area of the drift RNC 140.
• the FACH FP packets are sent to a peer FACH FP entity at the drift RNC 140 over an AAL2 (or other) connection.
• the peer FACH FP entity decapsulates the MAC-d SDU and identifies the priority contained in the FRAME FP header.
• the SDU and associated priority are passed to the MAC-c entity at the controlling RNC 140.
• the MAC-c layer is responsible for scheduling SDUs for transmission on the
• each SDU is placed in a queue corresponding to its priority and size. For example, if there are 16 priority levels, there will be 16 queue sets for each FACH, with the number of queues in each of the 16 queue sets depending upon the number of packet sizes accepted for the associated priority. As described hereinabove, SDUs are selected from the queues for a given FACH in accordance with some predefined algorithm (e.g., so as to satisfy the TFC requirements of the physical channel).
• the scheme described hereinbelow with reference to FIGS. 3 and 4 relates to data transmission in a telecommunications network and in particular, though not necessarily, to data transmission in a UMTS.
• the 3 GPP is currently in the process of standardizing a new set of protocols for mobile telecommunications systems.
• the set of protocols is known collectively as the UMTS.
• FIG. 3 a view of an exemplary second layer architecture of an exemplary next-generation system in accordance with the present invention is illustrated generally at 300.
• the exemplary second layer architecture 300 illustrates a simplified UMTS layer 2 protocol structure which is involved in the communication between mobile stations (e.g. mobile telephones), or more broadly UEs 110, and Radio Network Controllers (RNCs) 140 of a UMTS network 100.
• the RNCs 140 are analogous to the Base Station Controllers (BSCs) of existing GSM mobile telecommunications networks, communicating with the mobile stations via Node Bs 150.
• BSCs Base Station Controllers
• the layer 2 structure of the exemplary second layer architecture 300 includes a set of Radio Access Bearers (RABs) 305 that make available radio resources (and services) to user applications.
• RABs Radio Access Bearers
• Data flows (e.g., in the form of segments) from the RABs 305 are passed to respective Radio Link Control (RLC) entities 310, which amongst other tasks buffer the received data segments.
• RLC Radio Link Control
• RABs 305 are mapped onto respective logical channels 315.
• a Medium Access Control (MAC) entity 320 receives data transmitted in the logical channels 315 and further maps the data from the logical channels 315 onto a set of transport channels 325.
• MAC Medium Access Control
• the transport channels 325 are finally mapped to a single physical transport channel 330, which has a total bandwidth (e.g., of ⁇ 2Mbits/sec) allocated to it by the network.
• a physical channel is used exclusively by one mobile station or is shared between many mobile stations, it is referred to as either a "dedicated physical channel” or a "common channel”.
• a MAC entity connected to a dedicated physical channel is known as MAC-d; there is preferably one MAC-d entity for each mobile station.
• a MAC entity connected to a common channel is known as MAC-c; there is preferably one MAC-c entity for each cell.
• the bandwidth of a transport channel 325 is not directly restricted by the capabilities of the physical layer 330, but is rather configured by a Radio Resource Controller (RRC) entity 335 using Transport Formats (TFs).
• RRC Radio Resource Controller
• TFs Transport Formats
• the RRC entity 335 defines one or several Transport Block (TB) sizes.
• TB Transport Block Size
• PDU MAC Protocol Data Unit
• PDU MAC Protocol Data Unit
• TBS Transport Block Set
• MAC entity can transmit to the physical layer in a single transmission time interval (TTI).
• TTI transmission time interval
• TFC Transport Format Combination
• ⁇ TF1 (80, 80)
• the MAC entity 320 has to decide how much data to transmit on each transport channel 325 connected to it. These transport channels 325 are not independent of one another, and are later multiplexed onto a single physical channel 330 at the physical layer 330 (as discussed hereinabove).
• the RRC entity 335 has to ensure that the total transmission capability on all transport channels 325 does not exceed the transmission capability of the underlying physical channel 330. This is accomplished by giving the MAC entity 320 a Transport Format Combination Set (TFCS), which contains the allowed Transport Format Combinations for all transport channels.
• TFCS Transport Format Combination Set
• TFCS Transport Format Combination Set
• the RRC entity 335 has to restrict the total transmission rate by not allowing all combinations of the TFs.
• An example of this would be a TFCS as follows [ ⁇ (80, 0), (80, 0) ⁇ , ⁇ (80, 0), (80, 80) ⁇ , ⁇ (80, 0),
• TFCI Transport Format Combination indicator
• the TFCI ⁇ would correspond to the second TFC, which is ⁇ (80, 0), (80, 80) ⁇ , meaning that nothing is transmitted from the first transport channel and a single packet of 80 bits is transmitted from the second transport channel.
• TCP Transmission Control Protocol
• IP Internet Protocol
• ATM Asynchronous Transfer Mode
• GPS Generalized Processor Sharing
• WFQ Weighted Fair Queuing
• ratej. weight_i/(sum_of_all_active__weights) * maximum _r ate.
• GPS could be applied to the MAC entity in UMTS, with the weighting for each input flow being determined (by the RRC entity) on the basis of certain RAB parameters, which are allocated to the corresponding RAB by the network.
• RAB parameter may equate to a Quality of Service (QoS) or Guaranteed rate allocated to a user for a particular network service.
• TFC Transport Format Combination
• TFCS TFC Set
• Embodiments of this scheme allow the TFC selection process for a subsequent frame to take into account any backlogs which exists for the input flows. The tendency is to adjust the selected TFC to reduce the backlogs. Such a backlog may exist due to the finite number of data transmission possibilities provided for by the TFCS.
• Nodes at which the method of this scheme maybe employed include mobile stations (such as mobile telephones and communicator type devices) (or more generally UEs) and Radio Network Controllers (RNCs).
• the input flows to the MAC entity are provided by respective Radio Network Controllers
• each RLC entity provides buffering for the associated data flow.
• the step of computing a fair share of resources for an input flow is carried out by a Radio Network Controller (RNC) entity.
• RNC Radio Network Controller
• the step of computing a fair share of resources for an input flow includes the step of determining the weighting given to that flow as a fraction of the sum of the weights given to all of the input flows. The fair share may then be determined by multiplying the total output bandwidth by the determined fraction. Also preferably, this step may involve using the Generalised Processor Sharing (GPS) mechanism.
• GPS Generalised Processor Sharing
• the weighting for a data flow may be defined by one or more Radio Access Bearer (RAB) parameters allocated to a RAB by the UMTS network, where the RAB is associated with each MAC input flow.
• RAB Radio Access Bearer
• the method further includes the step of adding the value of the backlog counter to the computed fair share for that flow and selecting a TFC on the basis of the resulting sums for all of the input flows.
• the difference maybe subtracted from the backlog counter for the input flow.
• UMTS Media Access Control
• MAC Media Access Control
• TFCS TFC Set
• second processor means for adding to a backlog counter associated with each input flow the difference between the data transmission rate for the flow resulting from the selected TFC and the determined fair share, if the data transmission rate is less than the determined fair share, where the first processor means is arranged to take into account the value of the backlog counters when selecting a TFC for the subsequent frame of the output data flow.
• the first and second processor means are provided by a Radio Network Controller (RNC) entity.
• RNC Radio Network Controller
• a simplified UMTS layer 2 includes one Radio Resource Control (RRC) entity, a Medium Access Control (MAC) entity for each mobile station, and a Radio Link Control (RLC) entity for each Radio
• RRC Radio Resource Control
• MAC Medium Access Control
• RLC Radio Link Control
• the MAC entity performs scheduling of outgoing data packets, while the RLC entities provide buffers for respective input flows .
• the RRC entity sets a limit on the maximum amount of data that can be transmitted from each flow by assigning a set of allowed Transport Format Combinations (TFC) to each MAC (referred to as a TFC Set or TFCS), but each MAC must independently decide how much data is transmitted from each flow by choosing the best available Transport Format Combination (TFC) from the TFCS .
• TFC Transport Format Combinations
• the flowchart 400 is a flow diagram of a method of allocating bandwidth resources to, for example, the input flow streams ofa MAC entity of the layer 2 of FIG 3.
• an exemplary method in accordance with the flowchart 400 may follow the following steps. First, input flows are received at RLCs and the data is buffered (step 405). Information on buffer fill levels is passed to the MAC entity (step 410). After the information on buffer fill levels is passed, the fair MAC bandwidth share for each input flow is computed (step 415).
• the computed fair share of each is then adjusted by adding the contents of an associated backlog counter to the respective computed fair share (step 420).
• a TFC is selected from the TFC set to most closely match the adjusted fair shares (step 425).
• the RLC is next instructed to deliver packets to the MAC entity according to the selected TFC (step 420).
• the MAC entity may also schedule packets in accordance with the selected TFC (step 435). After packet scheduling, the traffic channels may be transported on the physical channel(s) (step 440). Once packet traffic has been transported, the backlog counters should be updated (step 445). The process may continue (via arrow 450) when new input flows are received at the RLCs, which buffer the data (at step 405).
• MAC entity on a per Transmission Time Interval (TTI) basis, the optimal distribution of available bandwidth using the Generalised Processor Sharing (GPS) approach ⁇ See, e.g., the article by A. K. Parekh et al. referenced hereinabove.) and by keeping track of how far behind each flow is from the optimal bandwidth allocation using respective backlog counters.
• GPS Generalised Processor Sharing
• the available bandwidth is distributed to flows by using the standard GPS weights, which may be calculated by the RRC using the RAB parameters.
• the method may first calculate the GPS distribution for the input flows and add to the GPS values the current respective backlogs. This is performed once for each 10ms TTI and results in a fair transmission rate for each flow. However, this rate may not be optimal as it may happen that there is not enough data to be sent in all buffers. In order to achieve optimal throughput as well as fairness, the fair GPS distribution is reduced so as to not exceed the current buffer fill level or the maximum allowed rate for any logical channel. A two step rating process is then carried out.
• TFCs Transport Format Combinations
• each TFC being scored according to how close it comes to sending out the optimal rate. In practice this is done by simply counting how much of the fair configuration a TFC fails to send (if a given TFC can send all packets at the fair rate, it is given a score of zero) and then considering only the TFCs which have the lowest scores. The closest match is chosen and used to determine the amount of packets sent from each queue. TFCs having an equal score are given a bonus score according to how many extra bits they can send (this can be further weighted by a Quality of Service rating in order to ensure that the excess capacity goes to the bearer with the highest quality class).
• TFCs having an equal score are given a bonus score according to how many extra bits they can send (this can be further weighted by a Quality of Service rating in order to ensure that the excess capacity goes to the bearer with the highest quality class).
• a two-level scheduling algorithm is applied, which enables the implementation of fair scheduling in environments in which the MAC needs to perform multiplexing.
• the two-level scheduling enables the provision of an arbitrary QoS to all flows that are multiplexed onto a single output channel.
• the MAC-c entity 500 may be incorporated in, and thus the principles of the present invention may be applied with, the UMTS MAC layer in an RNC, a UE, etc.
• relevant parameters for each logical channel are first received as input.
• a backlog counter (value) for each logical channel is maintained. In order to apply a fair queuing mechanism, these parameters are converted to GPS weights.
• tfcs [trch] [tfci] A two-dimensional array containing the TFCS . Each element of the array is a vector containing two integers, the TBS and the TBSS. It is assumed that the TFCS is stored in such a way that the most significant index is the Transport Channel Identifier.
• max _r ate The maximum rate that can be transmitted on all transport channels. Note that this is not typically the same as the sum of the maximum rates on each transport channel, as the transport capability on FACH or DCH channels is limited by the transport capability of the physical common channel. This is preferably calculated directly from the TFCS every time the TFCS is modified and/or limited.
• trch_max_rate [trch] An array that contains the maximum rate for each transport channel. This parameter, while actually optional, is used to ensure that if the guaranteed rate is higher than the maximum transport rate, then the backlog for the respective flow is not accumulated and the excess data rate can be given to other flow(s). This parameter is preferably calculated directly from the TFCS every time the
• TFCS is modified and/or limited.
• lch_qos_class [lch] An array containing the QoS class for each input flow ("logical channel"). This array is preferably re-computed when new input flows are added or old flows are removed.
• lch_guarjate[lch] An array containing the guaranteed rate for each input flow ("logical channel”). This array is preferably re-computed when new input flows are added or old flows are removed.
• lch_queuejill [lch] An array containing the number of packets in the input buffer for each incoming flow. This is the maximum number of packets that can be transmitted from this incoming flow ("logical channel") in this TTI. If more than this number is requested, then the RLC can provide padding, but for packets in QoS buffers (e.g., QoS buffers 510) this is not possible. This parameter is preferably updated before each scheduling decision.
• lch_pu_size [lch] An array containing the size of the packets in the input buffers for each incoming flow. This parameter may be updated only when the size of the packets/PDUs change, or when new channels are added.
• This exemplary version of the exemplary scheduling algorithm preferably employs two (2) "external" arrays, which may be stored at memory in between the scheduling decisions. Both of these arrays are updated once per scheduling decision: 1. lch_grJ>acklog[lch]: An array containing the current guaranteed rate backlog (i.e., how far behind the guaranteed rate this flow is) for each logical channel. This backlog may be specified in bits.
• two (2) more backlog arrays are preferably calculated for each scheduling decision:
• trch_gr_backlog An array containing the sum of all current guaranteed rate backlogs of the logical channels multiplexed to a given transport channel.
• trch_wfq An array containing the sum of all current fair queuing backlogs of the logical channels multiplexed to a given fransport channel.
• tfc_gr guarjate [trch] + trch_grJ>acklog [trch]
• the tfcjgr value is preferably reduced to the trch_queuejill value. This ensures that no unnecessary padding is requested. (It also ensures that if any flow has nothing to send, then nothing will be requested.)
• the tfcjwfq [trch] is preferably further modified to ensure that the WFQ scheduling does not request more bandwidth than that defined by the maxjrchjate value and/or the trch _queue Jill value (e.g., in bits).
• the TFCS is scanned through and every TFC is given three scores according to (i) how close the TFC is to tfcjgr, (ii) how close the TFC is to tfcjwfq, and (iii) how much of the excess bandwidth the TFC allocates to flows with different QoS classes. (Step 615.)
• the scores are determined as follows:
• these three scores are ranked in a defined priority.
• the TFCI that maximizes the grjcore is selected.
• the TFCI that maximizes the wfqjcore is selected.
• the TFCI with the maximum bonus jcore is chosen. This three-tiered selection process ensures that all the guaranteed rates are served first. If this is not possible, then the flows with the highest quality of service class are scheduled because the score is multiplied by "qosjlass".
• transport channels are analyzed only one at time, the situation is analogous to those of an IP/ ATM router, where several flows of different QoS classes share a single output channel. This suggests that a well-tested method like WFQ may be employed for multiplexing several logical channels to single transport channel.
• two backlog counters are already present. These two backlog counters can ensure a guaranteed rate and a fair allocation on average for each logical channel, so a simpler alternative is available.
• the TBSS is divided between logical channels by a three-stage process. (Step 620.) First, check if the TBSS is smaller than the trch_guarjate.
• FIG. 7 another view of the exemplary second layer architecture of an exemplary next-generation system in accordance with the present invention is illustrated generally at 700.
• the exemplary second layer architecture 700 includes additional details regarding elements of, and interrelationships between, various aspects of the second layer architecture of, for example, the Universal Mobile Telecommunications System (UMTS).
• UMTS Universal Mobile Telecommunications System
• the MAC layer of UMTS preferably schedules packets so that the total Quality of Service (QoS) provided to the end user fulfills the guarantees given when the Radio Access Bearer (RAB) 730 was established.
• QoS Quality of Service
• RAB Radio Access Bearer
• One resulting issue is guaranteeing (e.g., different) guaranteed bit rates to services having different QoS classes. It is preferable to guarantee that, if possible, all flows are given their guaranteed bit rate regardless of their QoS class. If this is not possible (e.g., due to high demand), then the flows with the higher (or highest) QoS classes are preferably given their respective guaranteed rates.
• Certain embodiment(s) of the present invention approach this problem of providing all flows a guaranteed bit rate by following a two-step scheduling process in a scheduler 735 located in the MAC layer.
• This two-level scheduling process guarantees that, if at all possible, all flows receive their guaranteed bit rates and also ensures that the guaranteed bit rates of the higher (and highest) priority flows are maintained as long as possible.
• these embodiment(s) may be implemented in the RNC node, the UE (node), etc.
• the MAC entity In each TTI, the MAC entity has to decide how much data to transmit on each transport channel connected to it. These transport channels are not independent of one another, and are later multiplexed onto a single physical channel at the physical layer
• the RRC 705 entity has to ensure that the total fransmission capability on all transport channels does not exceed the transmission capability of the underlying physical channel. This is done by giving the MAC entity a TFCS, which contains the allowed TFCs for all transport channels.
• FIG. 8 another exemplary method in flowchart form for scheduling data flows in accordance with the present invention is illustrated generally at 800.
• the scheduling process in the MAC layer includes the selection of a TFC from a TFCS using a two-step scoring process. This selection may be performed once for each TTI. Initially, several parameters are obtained for each logical channel.
• the QoS Class for each logical channel may be obtained from the corresponding RAB parameter.
• the QoS Class value may be obtained directly from the RAB parameter called "QoS Class", or it may alternatively be calculated from one or more RAB parameters using any suitable formula.
• the Guaranteed Rate for each logical channel may also be obtained from the corresponding RAB parameter.
• the Guaranteed Rate value may be obtained directly from the "Guaranteed Rate” RAB parameter, calculated from preassigned fair queuing weights using the GPS formula (as presented in "A Generalised Processor Sharing Approach to Flow Control in Integrated Services Networks: The Single Node Case", A. K. Parekh, R. G. Gallager, published in IEEE/ ACM Transactions On Networking, Vol. 1, No. 3, June
• the Queue Fill Level corresponds to a number of
• int maxTrch tfcs;Length( ); int tfc, tfci, qf, gr, rate, trch, trchGl; int tfcToUse;
• bits_to_send min(tbss, qf); /* Give score according to real bits that can be sent, but not
• these embodiment(s) are not fair, they still provide the guaranteed rate transfer rate to all service classes. Specifically, these embodiment(s) are optimized to provide best quality of service to flows having the highest QoS class(es), while still providing a minimum level of service to all flows. Furthermore, because no backlog memory need be updated each TTI, they can be faster to execute, even though they cannot guarantee fairness over the long run.

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