US007167487B2
`
`(12) United States Patent
`US 7,167,487 B2
`(10) Patent No.:
`Herrmann
`(45) Date of Patent:
`Jan. 23, 2007
`
`(54) NETWORK WITH LOGIC CHANNELS AND
`TRANSPORT CHANNELS
`
`OTHER PUBLICATIONS
`
`(75)
`
`Inventor: Christoph Herrmann, Aachen (DE)
`
`(73) Assignee: Koninklijke Philips Electronics N.V.,
`Eindhoven (NL)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 1004 days.
`
`(21) Appl. No.: 10/151,087
`
`(22)
`
`Filed:
`
`May 20, 2002
`
`(65)
`
`Prior Publication Data
`
`US 2003/0053344 A1
`
`Mar. 20, 2003
`
`(30)
`
`Foreign Application Priority Data
`
`May 21, 2001
`
`(DE)
`
`................................ 101 24 940
`
`(51)
`
`Int. Cl.
`(2006.01)
`H04] 3/18
`(52) US. Cl.
`...................................................... 370/477
`(58) Field of Classification Search ................ 370/337,
`370/442, 338, 329, 348, 437, 469, 342, 321,
`370/326, 477; 455/4352, 403
`See application file for complete search history.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3rd Generation Partnership Project; Technical Sspecification Group
`Radio Access Network; Services provided by the physical layer,
`(Release 1999) (3GPP TS 25.302, V3.7.0 (Dec. 2000).
`3rd Generation Partnership Project; Technical Sspecification Group
`Radio Access Network; MAC protocol specification,
`(Release
`1999) (3GPP TS 25.321, V3.7.0 (Mar. 2000).
`
`* cited by examiner
`
`Primary Examiner%hi Pham
`Assistant ExamineriAlexander O. Boakye
`
`(57)
`
`ABSTRACT
`
`The invention relates to a network with a first plurality of
`logic channels with which is associated a second plurality of
`transport channels,
`which transport channels are provided for transmitting trans-
`port blocks formed from packet units of the logic channels,
`wherein a plurality of valid transport format combinations is
`allocated to the transport channels, which combinations
`indicate the transport blocks provided for transmission on
`each transport channel,
`wherein a selection algorithm is provided for selecting the
`transport format combinations, and
`wherein it is provided that the selection of the transport
`format combinations is carried out while maintaining a
`minimum bit rate applicable to the respective logic channel.
`
`6,850,540 B1 *
`
`2/2005 Peisa et al.
`
`................. 370/468
`
`13 Claims, 2 Drawing Sheets
`
`
`
`BLACKBERRY 1001
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`BLACKBERRY 1001
`
`

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`U.S. Patent
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`Jan. 23, 2007
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`Sheet 1 of2
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`US 7,167,487 B2
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`[3/2 i”
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`FIG. 1
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`U.S. Patent
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`Jan. 23, 2007
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`Sheet 2 of 2
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`US 7,167,487 B2
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`US 7,167,487 B2
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`1
`NETWORK WITH LOGIC CHANNELS AND
`TRANSPORT CHANNELS
`
`The invention relates to a network with a first plurality of
`logic channels with which is associated a second plurality of
`transport channels, said transport channels being designed
`for the transmission of transport blocks formed from packet
`units of the logic channels.
`Such a network is known from the 3rd Generation Part-
`nership Project
`(3GPP); Technical Specification Group
`(TSG) RAN; Working Group 2 (WG2); Radio Interface
`Protocol Architecture; TS 25.302 V3.6.0), which describes
`the function of the MAC layer (MAC:Medium Access
`Control) of a radio network. Aphysical layer offers transport
`channels or transport links to the MAC layer. The MAC
`layer makes logic channels or logic links available to an
`RLC layer (RLC:Radio Link Control). The packet units
`formed in the RLC layer are packed in transport blocks in
`the MAC layer, which blocks are transmitted from the
`physical layer through physical channels to a terminal, or the
`other way about, by the radio network control. Apart from
`such a multiplex or demultiplex function, the MAC layer
`also has the function of selecting suitable transport format
`combinations (TFC). A transport format combination repre-
`sents a combination of transport formats for each transport
`channel. The transport format combination describes inter
`alia how the transport channels are multiplexed into a
`physical channel in the physical layer.
`The invention has for its object to provide a network
`which comprises an optimized selection process for select-
`ing a suitable transport format combination.
`According to the invention, this object is achieved by
`means of a network with a first plurality of logic channels
`with which a second plurality of transport channels is
`associated,
`which transport channels are provided for transmitting trans-
`port blocks formed from packet units of the logic chan-
`nels,
`wherein a plurality of valid transport format combinations is
`allocated to the transport channels, which combinations
`indicate the transport blocks provided for transmission on
`each transport channel,
`wherein a selection algorithm is provided for selecting the
`transport format combinations, and
`wherein it is provided that the selection of the transport
`format combinations is carried out while maintaining a
`minimum bit rate applicable to the respective logic chan-
`nel.
`
`A valid transport format combination is understood to be
`a combination which can be signaled. Signaling of the
`transport format combinations takes place by means of
`signaling bits which indicate to the relevant receiving side
`which transport format combination was used for the trans-
`mission. The number of signaling bits available for signaling
`is limited, in particular in wireless networks. The result of
`this is that not all possible transport format combinations can
`be signaled and are valid according to the definition given
`above. The number of valid transport format combinations is
`instead limited by the number of signaling bits which are
`available.
`
`The invention is based on the idea of integrating into the
`selection algorithm for selecting a suitable or optimum
`transport format combination the condition that a minimum
`bit rate can be guaranteed suitable for the respective logic
`channels. Such a minimum bit rate is often defined by the
`relevant application. Thus a speech connection usually
`requires a constant bit rate, which thus will coincide with the
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`given minimum bit rate here. Such minimum bit rates as
`characteristics of the quality of service required by an
`application in the logic channels are defined, for example, in
`the specification: 3”] Generation Partnership Project; Tech-
`nical Specification Group Services and System Aspects;
`“QoS Concept and Architecture” TS23.107v350.
`The advantage of such an integration of the minimum bit
`rate requirement
`into the TFC selection algorithm is in
`particular that the two functions (TFC selection and com-
`pliance with the minimum bit rate requirement) can be
`implemented in a common unit of the mobile station or of
`the network. The implementation is possible both in soft-
`ware and in hardware.
`
`The requirement to comply with the minimum bit rate is
`to be understood here such that it is attempted as much as
`possible in the selection of the TFC to maintain the mini-
`mum bit rate with respect to a given measuring interval in
`the selection of the TFC. Should this be impossible because
`of the packet units available in the individual logic channels,
`TFCs may alternatively be chosen which fall below the
`minimum bit rate.
`
`An advantageous possibility of implementing a security
`function for taking into account and complying with the
`minimum bit rate consists in that a moving measurement
`window of, for example, 5 transmission time intervals TTl
`is provided.
`A transmission time interval TTl corresponds to a number
`of radio frames (RF) and is equal to at least one radio frame.
`It
`indicates the number of radio frames over which the
`
`interleaving extends. lnterleaving is a combination proce-
`dure in which information units (symbols) from consecutive
`radio frames are interwoven in time at the transmitter end.
`
`The MAC layer supplies a plurality of transport blocks to the
`physical layer in each transmission time interval. The trans-
`mission time interval is specific to a transport channel and
`belongs to the semi-static part of the transport format. When
`the physical layer receives a plurality of transport blocks
`designed for transmission through a transport channel at the
`start of a transmission time interval comprising 11 radio
`frames, each transport block of this plurality is subdivided
`into 11 segments (segmentation of transport blocks). The 11
`segments of each transport block are transmitted in the 11
`consecutive radio frames of the transmission time interval.
`All 11 radio frames of the transmission time interval will then
`
`show the same sequence of segments.
`The moving measurement window for measuring the bit
`rate is then shifted by one TTl in a sliding fashion each time,
`such that the bit rate of the final 4 TTls is measured each
`
`time. The number of transport blocks to be transmitted in the
`current, 5th TTl is then determined from the measured bit
`rate of the final 4 TTls, such that the minimum bit rate is
`maintained.
`
`A further advantage of the invention is that the determi-
`nation of the minimum bit rate can take place through
`implementation of the sliding measurement window and that
`the compliance with the minimum bit rate can be achieved
`at the level of the MAC layer. This offers the advantage over
`a separate implementation of a function for monitoring the
`compliance with the bit rate, for example at the application
`level, that the measurement at the MAC layer level is more
`accurate, because control information added in the MAC
`layer and in the RLC layer (for example the MAC and RLC
`headers) can be directly included in the measurement
`because it is contained in the transport blocks.
`In the advantageous embodiment of the invention as
`defined in claim 2, the selection algorithm for selecting a
`suitable or optimum transport format combination takes into
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`US 7,167,487 B2
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`3
`account and integrates the condition that a maximum bit rate
`provided for the logic channels is maintained. Maintaining
`such a maximum bit rate for the respective individual logic
`channels, which are preferably scanned in succession in the
`allocation algorithm, ensures that logic channels of lower
`priority can still send packet units when the waiting lines of
`logic channels of higher priority contain so many packet
`units that logic channels of lower priority would be unable
`to send any packet unit at all if the maximum bit rate were
`not taken into account. The provision of a maximum bit rate
`thus ensures a distribution of the available transmission
`
`capacity in accordance with the respective maximum bit
`rates. Such maximum bit rates for the logic channels as
`properties characteristic of a quality of service desired for an
`application are defined, for example, in the specification 3rd
`Generation Partnership Project; Technical Specification
`Group Services and System Aspects; “QoS Concept and
`Architecture” TS23.107v350.
`The maximum bit rates can be taken into account as an
`
`absolute upper limit in the total selection algorithm. This
`means that the maximum bit rate is not exceeded in the TFC
`
`last selected. The maximum bit rate, however, may be taken
`into account temporarily only, for example only during part
`of the algorithm or a partial step in the selection.
`It
`is
`possible in particular to lift the condition of the maximum bit
`rate not to be exceeded at the end of the selection algorithm
`and to allocate the still remaining packet units to the highest
`possible extent.
`In the advantageous selection algorithm of claim 3, the
`selection algorithm first comprises an allocation sequence.
`In this first allocation sequence,
`the logic channels are
`utilized one after the other, and the packet units waiting in
`the storage units of the logic channels are allocated to the
`respective transport channels on the basis of two criteria
`each time. A packet unit allocated to a transport channel for
`transmission in this first allocation sequence will be taken
`into account at the end of the selection algorithm in each and
`every case, i.e. it is transmitted. This means that the quantity
`of valid transport format combinations allowing the trans-
`mission of the packet units allocated up to the respective
`moment and the transmission of the newly allocated packet
`units becomes successively smaller upon each allocation of
`packet units.
`The utilization of the logic channels takes place prefer-
`ably in accordance with their priorities, i.e. the logic channel
`of highest priority is used first, then the logic channel with
`the next highest priority, etc.
`The first criterion taken into account is that in each case
`
`only so many packet units are allocated that the sum of the
`packet units allocated to the respective channel up to the
`present moment and the newly allocated packet units for this
`transport channel corresponds to a transport format which is
`contained in a valid transport format combination. This
`means that it
`is ensured that no empty packet units are
`transmitted, even if no further packet units are allocated to
`the transport channel any more after that. The substitution
`with empty packet units is often also denoted with the term
`“padding”.
`The second criterion taken into account, over which,
`however,
`the first criterion takes precedence,
`is that the
`number of the allocated packet units is chosen such that it
`comes as close as possible to the minimum bit rate provided
`for the respective logic channel in each case. If fewer packet
`units are available in the logic channel than are required for
`achieving the minimum bit rate, all packet units present are
`accordingly allocated, in as far as this results in a valid TFC.
`If more packet units are present in the logic channel than are
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`required for achieving the minimum bit rate, only a number
`of packet units corresponding to the minimum bit rate is
`allocated, as far as possible and as far as this results in a valid
`TFC.
`
`After the first allocation sequence, a further allocation
`sequence is provided in which a further allocation of yet
`remaining packet units takes place. The logic channels are
`once more utilized serially, preferably in order of priority.
`Such a two-stage allocation has the advantage that the
`condition as to the minimum bit rate to be observed is
`
`integrated into the selection algorithm in the first allocation
`sequence, and that accordingly the minimum bit rate is
`guaranteed as much as possible for all logic channels. This
`leads to a suitable treatment of all logic channels in the
`allocation.
`
`Claim 4 relates to an advantageous embodiment of the
`second allocation sequence. It is again provided here as a
`criterion of highest priority that no transmission of empty
`packet units (padding) is allowed.
`It is attempted in complying with this criterion to allocate
`as many packet units as possible to the logic channels, while
`the maximum bit rate obtaining for each respective logic
`channel is not to be exceeded.
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`This leads to an improved tailoring to all logic channels
`in the allocation.
`
`The third allocation sequence which follows the second
`allocation sequence differs from the first one, according to
`claim 5, only in that the condition as to the maximum bit rate
`is no longer observed. Lifting of this condition in the third
`sequence is advantageous if as large as possible a total
`number of packet units is to be transmitted. This lifting takes
`place not in the second allocation sequence already in this
`embodiment of the invention, because in that case logic
`channels of low priority would be disadvantaged in the
`allocation because of the requirement of the maximum bit
`rate.
`
`It is alternatively possible, however, to end the selection
`algorithm after the second allocation sequence. This has the
`advantage that the total bit rate is lower, and thus also the
`required transmission power. The resulting interference with
`adjoining radio cells is also reduced thereby.
`In the advantageous embodiment of the invention as
`defined in claim 6, the condition as to the maximum bit rate
`to be observed is lifted already in the second allocation
`sequence and is no longer taken into account, at least only
`for the final
`logic channel which is associated with a
`transport channel. The condition as to the maximum bit rate
`to be observed may alternatively be lifted earlier,
`for
`example for the penultimate logic channel which is associ-
`ated with a transport channel. The last logic channel, in
`which the maximum bit rate condition is lifted, may then
`deliver as many packet units as possible,
`in as far as
`corresponding suitable valid transport format combinations
`are still available.
`The invention also relates to a radio network control and
`to a terminal in a wireless network, as well as to a method
`of selecting a transport format combination.
`A few embodiments of the invention will be explained in
`more detail below with reference to the drawing comprising
`FIGS. 1 and 2, wherein:
`FIG. 1 shows a wireless network with a radio network
`control and several terminals, and
`FIG. 2 shows a layer model for clarifying various func-
`tions of a terminal or a radio network control.
`
`FIG. 1 shows a wireless network, for example a radio
`network, with a radio network controller (RNC) 1 and a
`plurality of terminals 2 to 9. The radio network controller 1
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`5
`is responsible for the control of all components taking part
`in the radio traffic such as, for example, the terminals 2 to 9.
`An exchange of control and payload data takes place at least
`between the radio network controller 1 and the terminals 2
`
`to 9. The radio network controller 1 establishes respective
`links for the transmission of payload data.
`Usually the terminals 2 to 9 are mobile stations, while the
`radio network controller 1 is fixedly installed. A radio
`network controller 1, however, may alternatively be dis-
`placeable or mobile in certain cases.
`The wireless network serves to transmit, for example,
`radio signals by the FDMA, TDMA, or CDMA methods
`(FDMA:frequency division multiplex access, TDMAfiime
`division multiplex access, CDMA:code division multiplex
`access), or in accordance with a combination of these
`methods.
`
`In the CDMA method, which is a special code spreading
`method, binary information (data signal) originating from a
`user is modulated with a different code sequence each time.
`Such a code sequence consists of a pseudo-random square-
`wave signal (pseudo-noise code) whose rate, referred to as
`chip rate,
`is usually much higher than that of the binary
`information. The duration of a square-wave pulse of the
`pseudo-random square-wave signal
`is denoted the chip
`interval TC.
`l/TC is the chip rate. The multiplication or
`modulation of the data signal by the pseudo-random square-
`wave signal leads to a spreading of the spectrum around the
`spreading factor NC:T/TC, where T is the duration of one
`square-wave pulse of the data signal.
`Payload data and control data between at least one ter-
`minal
`(2 to 9) and the radio network controller 1 are
`transmitted through channels designated by the radio net-
`work controller 1. A channel is defined by a frequency range,
`a time range, and, for example in the CDMA method, by a
`spreading code. The radio link between the radio network
`controller 1 and the terminals 2 to 9 is denoted the downlink,
`and from the terminals to the base station the uplink. Data
`are thus sent from the base station to the terminals through
`downlink channels, and from terminals to the base station
`through uplink channels.
`For example, a downlink control channel may be pro-
`vided, which is used for distributing control data from the
`radio network controller 1 to all terminals 2 to 9 before a
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`connection link is built up. Such a channel is denoted the
`downlink distribution control channel or broadcast control
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`channel. To transmit control data before the building-up of
`a connection from a terminal 2 to 9 to the radio network
`
`for example, an uplink control channel
`controller 1,
`appointed by the radio network controller 1 may be used, to
`which, however, other terminals 2 to 9 may also have access.
`An uplink channel which can be used by several or all
`terminals 2 to 9 is denoted a common uplink channel. After
`a connection has been built up, for example between a
`terminal 2 to 9 and the radio network controller 1, payload
`data are transmitted through a downlink and an uplink
`payload channel. Channels which are built up exclusively
`between one transmitter and one receiver are denoted dedi-
`
`cated channels. Usually, a payload channel is a dedicated
`channel which can be accompanied by a dedicated control
`channel for the transmission of link-specific control data.
`To achieve that payload data can be exchanged between
`the radio network controller 1 and a terminal, it is necessary
`for a terminal 2 to 9 to be synchronized with the radio
`network controller 1. It is known, for example, from the
`GSM system (GSM:Global System for Mobile communi-
`cation),
`in which a combination of FDMA and TDMA
`methods is used,
`to determine first a suitable frequency
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`range on the basis of given parameters and then the temporal
`position of a frame (frame synchronization), by means of
`which the time sequence for the transmission of data is
`obtained. Such a frame is always necessary for data syn-
`chronization of terminals and the base station in the TDMA,
`FDMA, and CDMA methods. Such a frame may comprise
`several sub-frames, or may form a superframe together with
`other, consecutive frames.
`The exchange of control and payload data via the radio
`interface between the radio network controller 1 and the
`
`terminals 2 to 9 may be clarified with reference to the
`example of a layer model or protocol architecture as shown
`in FIG. 2 (cf.
`for example: 3”] Generation Partnership
`Project (3GPP); Technical Specification Group (TSG) RAN;
`Working Group 2 (WG2); Radio Interface Protocol Archi-
`tecture; TS 25.301 V3.6.0). The layer model comprises three
`protocol layers: the physical layer PHY, the data connection
`layer with the sub-layers MAC and RLC (FIG. 2 shows a
`plurality of units of the sub-layer RLC), and the layer RRC.
`The sub-layer MAC is responsible for the medium access
`control, the sub-layer RLC for the radio link control, and the
`layer RRC for the radio resource control. The layer RC is
`responsible for signaling between the terminals 2 to 9 and
`the radio network controller 1. The sub-layer RLC serves to
`control a radio link between a terminal 2 to 9 and the radio
`
`network controller 1. The layer RRC controls the layers
`MAC and PHY via control lines 10 and 11. The layer RRC
`can control the configuration of the layers MAC and PHY in
`this manner. The physical layer PHY offers transport chan-
`nels or transport links 12 to the MAC layer. The MAC layer
`makes logic channels or logic links 13 available to the RLC
`layer. The RLC layer is accessible to applications via access
`points 14.
`Packet units are formed in the RLC layer and are packed
`in transport blocks in the MAC layer, which blocks are
`transmitted from the radio network controller to a terminal,
`or the other way about, through physical channels. Apart
`from such a multiplex and demultiplex function, the MAC
`layer also has the function of selecting suitable transport
`format combinations (TFC). Atransport format combination
`represents a combination of transport formats for each
`transport
`channel. The
`transport
`format
`combination
`describes inter alia how the transport channels are multi-
`plexed into a physical channel in the physical layer (time
`multiplex).
`Each transport format comprises a dynamic and a semi-
`static part. The dynamic part describes a transport block set
`(TBS) which is transmitted in a transport channel during a
`transmission time interval (TTI), and the semi-static part
`comprises, for example, information about the nature of the
`error-correcting coding. The semi-static part will only
`change through a reconfiguration of the physical channel. A
`transport block set
`is defined as a plurality of transport
`blocks which is exchanged between the physical layer and
`the MAC layer. The size of a transport block is defined by
`the number of bits of one packet unit of the RLC layer and
`the number of bits of added control information (header) of
`the MAC layer.
`The term “transport format” in the following description
`will be understood to denote only the dynamic part of the
`transport format.
`A transmission time interval corresponds to a number of
`radio frames (RF) and is at least one radio frame. It indicates
`the number of radio frames over which the interleaving
`extends. Interleaving is a combination in time of information
`units (symbols) from consecutive radio frames at the trans-
`mitter end. The MAC layer supplies a transport block set to
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`US 7,167,487 B2
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`The logic channels are numbered here in order of decreas-
`ing priority, i.e. LC 1 has the highest priority and LC NLC has
`the lowest priority: the lower the number, the higher the
`priority.
`Logic channels with different but adjoining numbers may
`have the same priority.
`If logic channels of the same priority (i.e. adjoining
`numbers) are present, and are imaged on transport channels
`which are active at the same time, the fairness of allocation
`may be optimized in that the logic channels are cyclically
`shifted in position from one TTl to the next: if LC 3, 4, and
`5 have the same priority, the sequence at the start of the first
`TTl would be 3, 4, 5, in the next TTl 3*:4, 4*:5, 5*:3, and
`so on. It is achieved thereby that not always the same logic
`channel at this level of priority is scanned first at the start of
`a TTl.
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`Further meanings of symbols:
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`SLogCh(t): the number of logic channels (identified by their
`numbers) which are imaged on the same transport channel
`TC t.
`
`SLogCh(t, L): the list of logic channels (identified by their
`numbers) which are imaged on the same transport channel
`TC t, starting with LC 1 and in rising numbers up to but
`not including LC L.
`t(L): the transport channel TC t on which LC L is imaged.
`N(L): the number of transport blocks allocated to LC L as
`part of TF(t(L)) in one TFC.
`A transport block comprises a number of bits defined by
`the transport block size.
`minBr and maxBr denote the minimum and maximum
`
`admissible bit rate, respectively, with respect to a given
`observed time period. minBr and maxBr serve to determine
`further quantities which are defined below.
`is defined on the basis of a
`a verage
`The average bit rate R
`“window” with size W:
`
`Raverage: — 53m“, W, L) with—W ,
`
`I Z
`
`SBzzsU, W, L): =
`
`k:max(0,lrW+1)
`
`N(k, L) -blocksize.
`
`in which S3.150: W, L) indicates the number of bits which
`were transmitted by LC L during the last W TTls%ounting
`from the 1‘11 TTl since the transmission was started on LC L.
`N(k,L) here denotes the number of transport blocks of LC L
`which were allocated for the transmission in TTl k. (If l<W,
`i.e. at the start of the transmission, the viewing interval is
`obviously only 1 TTls.)
`Nmm(l,L) denotes the smallest number of transport blocks
`that can be allocated to the LC L for transmission in the 1‘11
`TTl, such that the average bit rate Ravemgem’m" with respect
`to the W preceding TTls up to the 1‘11 TTl does not fall below
`the value minBr.
`
`Nmax(l,L) denotes the greatest number of transport blocks
`that can be allocated to the LC L for transmission in the 1‘11
`
`TTl, such that the average bit rate Ravemgemma" with respect
`to the W preceding TTls up to the 1‘11 TTl does not fall below
`the value maxBr.
`
`Given certain values for minBr and maxBr, these defini-
`min
`tions lead to the following conditions for N (LL) and
`Nmax(15L):
`
`7
`the physical layer during each transmission time interval.
`The transmission time interval
`is specific to a transport
`channel and belongs to the semi-static part of the transport
`format. When the physical layer receives a transport block
`set designed for transmission through a transport channel
`from the MAC layer at the start of a transmission time
`interval comprising 11 radio frames, each transport block of
`this set will be subdivided into 11 segments (segmentation of
`transport blocks). The 11 segments of each transport block are
`transmitted in the 11 consecutive radio frames of the trans-
`mission time interval. All 11 radio frames of the transmission
`
`time interval contain the same sequence of fragments then.
`The MAC layer serves to select the suitable transport
`format for each transport channel. It is necessary in this
`selection to take into account the priorities of the logic
`channels between the RLC and MAC layers, denoted the
`MAC logical priority (MLP) hereinafter, the occupation of
`the waiting lines in the RLC layer (buffer occupancy:BO),
`the transmission time intervals TTl of the transport channels
`associated with the logic channels, and subsets of transport
`format combinations. A waiting line in the RLC layer
`contains packet units which are to be transmitted from the
`RLC layer through the MAC layer to the physical layer. A
`subset of the transport format combination is part of the
`possible total set of transport format combinations. Subsets
`are used for limiting the number of possible transport format
`combinations because the number of bits for signaling to the
`reception side which transport format combination was used
`for the transmission is also limited.
`
`imaged
`(or the logic channel(s)
`A transport channel
`thereon) is/are denoted inactive in the radio frame if the start
`of the radio frame does not coincide with the start of the
`
`transmission time interval of the transport channel. It is (they
`are) denoted active in the opposite case. In the case of the
`shortest
`transmission time interval corresponding to the
`length of one radio frame of, for example, 10 ms,
`the
`associated transport channel
`is never inactive because a
`transport block will require at least this shortest transmission
`time interval for transmitting its data. A transport channel
`may indeed be inactive in this sense in the case of longer
`transmission time intervals (for example 20 ms).
`A selection algorithm for selecting an optimum transport
`format combination is carried out in the MAC layer at each
`start of a radio frame. This algorithm may be implemented
`in the software or in the hardware, in the mobile station or
`in the network.
`
`First a few parameters and variables are defined for the
`representation and clarification of the selection algorithm:
`Symbols have the following meanings:
`$2: the number of all transport format combinations TFC
`within the set TFCS of all transport format combinations
`which can be supported given the existing maximum
`transmission power of the mobile station.
`TF(t): a number of transport blocks of given size which are
`transmitted through transport
`channel TC t, with
`t:l, .
`.
`.
`, NTC, and NTC is the number of transport
`channels.
`
`A transport format combination TFC is defined here as
`TFC:(TF(1), TF(2), .
`.
`.
`, TF(NTC)), for which it is ignored
`that a transport format in addition comprises semi-static
`attributes, for example the method of error correction cod-
`ing.
`BO(L): the buffer occupancy B0 of the logic channel LC L,
`with L:l, .
`.
`.
`, NLC, where NLC represents the number of
`logic channels.
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`7
`
`

`

`US 7,167,487 B2
`
`,
`z minBr
`
`-
`Rg‘gg‘mgga): =
`
`
`58in“ — 1, W - 1, L) + Nmin(l, L)-blocksize
`W
`
`quvgagga): = 58in“ — 1, W -1, L) ;-VNmax(l, L) -block51ze Z maxBr
`, minBr- W —sB;,S(l— 1, W — 1, L)
`blocksize
`2 ijnU, L): ($47]
`maxBr- W —SB;,S(1— 1, W — 1, L)
`blocksize
`2 Nmax(l, L): floor(—]
`
`in which floor(x)::[xj is the highest integer number smaller
`than or equal to x, and ceil(x)::[x] is the smallest integer
`number greater than or equal to x.
`The selection algorithm now preferably proceeds in the
`following steps:
`1. Determine for each logic channel LC L the lowest number
`of blocks Nmm(L) that can be transported in the present
`TTl (while forming a moving sum over the W last TTls)
`without falling below the minimum bit rate for the chan-
`nel LC L.
`
`Determine for each logic channel LC L the greatest
`number of blocks Nmax(L) that can be transported in the
`present TTI (while forming a moving sum over the W
`last TTls) without the maximum bit rate for the channel
`LC L being exceeded.
`2. Set the iteration variable ITEFR for 1.
`
`Now the following loop is traversed:
`3. Set L::1.
`
`4. Set 81::82 (82 as defined above).
`5. If ITER::1 (minBr condition):
`Form 82 as the number of the transport format combina-
`tions TFC in 81 which contain a number of transport
`blocks waiting in the waiting line of LC L and coming
`closest to the value Nmin(L) or (with the use of padding
`blocks) which contain more than this numberiwhile
`taking into account all allocated transport blocks of
`logic channels already inspected which are imaged on
`the same transport channel (i.e. contained in SLOgCh(t
`(L),L). Formally, $2 (in dependence on L) i