DESCRIPTION
COMMUNICATION APPARATUS, TRANSMISSION DATA GENERATION
PROGRAM AND TRANSMISSION DATA GENERATION METHOD
TECHNICAL FIELD
[0001] The present invention relates to a communication
apparatus, a transmission data generation program, and a
transmission data generation method.
BACKGROUND ART
[0002] In recent years, a communication specification
called Long Term Evolution (LTE) is much discussed as a new
radio communication system standard. LTE has come to the
attention of the 3rd Generation Partnership Project (3GPP),
which is one of the communication standardization projects,
and, for example, improvement of Layer 2 corresponding to
the data link layer is in progress there.
[0003] More specifically, as illustrated in FIG. 1,
Layer 2 in LTE includes three sub-layers of the Packet Data
Convergence Protocol (PDCP) layer, the Radio Link Control
(RLC) layer, and the Medium Access Control (MAC) layer.
PDCP entities and RLC entities belonging to the PDCP layer
and the RLC layer respectively are present in a quantity of
as many as the number (n in FIG. 1) of logical channels
(LCH: Logical CHannel) used for radio communication and
there is a one-to-one correspondence there between. In
each of the n PDCP entities, a PDCP layer header is added
to transmission data, thus obtaining a Packet Data Unit
(PDU) of the PDCP layer, which is output to the
corresponding RLC entity. The PDU becomes a Service Data
Unit (SDU) in the RLC layer and after a RLC layer header is
being added by each RLC entity, a PDU of the RLC layer is
obtained. That is, if a PDU of an upper sub-layer is
output to a lower sub-layer, the PDU is handled as an SDU
of the lower sub-layer. Then, if the header of each sub-
layer is added to the SDU in the lower sub-layer, a PDU of
the lower sub-layer is obtained.
[0004] If a PDU of the RLC layer (hereinafter, referred
to as "RLC-PDU") is output from each RLC entity to the MAC
layer, these RLC-PDUs are multiplexed and become a PDU of
the MAC layer (hereinafter, referred to as "MAC-PDU") after
MAC layer headers are added thereto. Layer 1 processing
corresponding to the physical layer is performed thereon
before being transmitted. At this point, a MAC entity
belonging to the MAC layer decides the size of the free
space in a MAC-PDU from radio resources such as the
bandwidth and power available for transmission of data and
allocates the RLC-PDU output from each of n RLC entities to
the free space in the MAC-PDU for multiplexing when
appropriate.
[0005] That is, as illustrated, for example, in FIG. 2,
an RLC-PDU obtained by adding the RLC header to an SDU in
the first RLC entity (hereinafter, referred to as "RLC#1")
and an RLC-PDU obtained by adding the RLC header to an SDU
in the second RLC entity (hereinafter, referred to as
"RLC#2") are each handled as MAC-SDUs for multiplexing in
the MAC layer. The header in the MAC layer (MAC header)
and control information are added to the two multiplexed
MAC-SDUs to obtain a MAC-PDU.
[0006] The obtained MAC-PDU is transmitted after Layer 1
processing (not illustrated) is performed thereon. In the
MAC layer, retransmission control by a hybrid automatic
repeat request (HARQ: Hybrid Automatic Repeat reQuest)
using Stop & Wait composed of n channels is also exercised.
In HARQ in the MAC layer, a MAC-PDU is maintained during
transmission and also error correction processing and
Cyclic Redundancy Check (CRC) coding are performed on the
MAC-PDU. If a reception result of a MAC-PDU is
unacceptable for reception (that is, an error detection
result by CRC code is unacceptable), the receiving side
returns a NACK to the sending side indicating the
unacceptability. On the other hand, if a reception result
of a MAC-PDU is acceptable for reception (that is, an error
detection result by CRC code is acceptable), the receiving
side returns an ACK to the sending side indicating the
acceptability. If a NACK is received, the MAC-PDU
maintained from the initial transmission is retransmitted
by the MAC layer by the sending side. If an ACK is
received, the MAC-PDU maintained from the initial
transmission is discarded.
[0007] If an ACK is not returned after repeatedly
retransmitting one MAC-PDU a predetermined maximum number
of retransmission times, the relevant MAC-PDU is also
discarded. In preparation for such a case, retransmission
control by an automatic repeat request (ARQ) using
Poll/Status information is exercised in the RLC layer.
More specifically, the RLC layer on the sending side adds
Poll information to an RLC-PDU and transmits the RLC-PDU to
request Status information from the RLC layer on the
receiving side. The RLC layer on the receiving side
detects the Poll information from the received RLC-PDU,
checks for missing RLC-PDU(s) from the sequence numbers of
the RLC-PDU(s) received to date, and creates Status
information and transmits the Status information to the RLC
layer on the sending side. The RLC layer on the sending
side retransmits RLC-PDU(s) missing on the receiving side
based on the received Status information.
[0008on-Patent Document 1: 3GPP TS 36.300 V8 . 5. 0
(2008-05), "Evolved Universal Terrestrial Radio Access (E-
UTRA) and Evolved Universal Terrestrial Radio Access
Network (E-UTRAN); Overall description; Stage 2 (Release
8)"
DISCLOSURE OF INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
{§£&%¥ The free space size of a MAC-PDU is decided in
accordance with radio resources and changes every moment so
that RLC-PDUs may not always be multiplexed in proper
quantities in the free space of a MAC-PDU. Thus, one RLC-
PDU may be divided so that each of RLC-PDUs obtained by
division may be multiplexed into free space of different
MAC-PDUs. More specifically, as illustrated, for example,
in FIG. 3, a case will be considered when four PDUs of the
PDCP layer (hereinafter, referred to as "PDCP-PDU") with
mutually different sizes are multiplexed into two MAC-PDUs
(MAC-PDU#1 and MAC-PDU#2) for transmission. Priorities in
accordance with the importance of data or Quality of
Service (QoS) are given to the four PDCP-PDUs.
[^Q^Qjr In such a case, RLC#1 that has acquired the PDCP-
PDU with the highest priority attaches the header
(indicated by "H" in FIG. 3) to the PDCP-PDU to multiplex
the RLC-PDU (RLC-PDU#1) into MAC-PDU#1. The RLC-PDU with
the second highest priority will be multiplexed into the
remaining space of the MAC-PDU#1, but the free space size
of the MAC-PDU#1 is insufficient and RLC#2 that has
acquired the PDCP-PDU with the second highest priority
divides the PDCP-PDU and sets each divided PDCP-PDU as a
RLC-SDU. That is, a header is attached to each of the two
RLC-SDUs obtained by dividing one PDCP-PDU.
[p-et-TT Then, the RLC#2 multiplexes one RLC-PDU#2-1
obtained by adding the header thereto into the MAC-PDU#1
and the other RLC-PDU#2-2 into the MAC-PDU#2. Thus, the
PDCP-PDU with the second highest priority is divided and
the two obtained RLC-PDU#2-1 and RLC-PDU#2-2 are
multiplexed into free space of the MAC-PDU#1 and MAC-PDU#2
respectively. Then, RLC-PDU#3 containing the whole PDCP-
PDU with the third highest priority and RLC-PDU#4
containing a portion of the PDCP-PDU with the fourth
highest priority are multiplexed into the remaining space
of the MAC-PDU#2.
[Q&tZV However, if a PDCP-PDU is divided and each of the
divided PDCP-PDUs become an RLC-SDU, an RLC header will be
added to each RLC-SDU, thus, increasing the space of a MAC-
PDU allocated to the header. That is, radio resources
consumed for transmitting headers attached to RLC-SDUs will
increase. The header is not data containing information to
be transmitted and thus, if the proportion occupied by
headers of the RLC layer in MAC-PDUs increases, there is a
problem of decreasing transmission efficiency of data. In
other words, if one PDCP-PDU is divided and the number of
RLC-SDUs is thereby increased, data throughput decreases.
At the same time, it becomes necessary for the receiving
side to couple and reassemble a plurality of RLC-SDUs into
one PDCP-PDU and therefore, RLC layer processing loads also
increase on the receiving side with an increasing number of
divided PDCP-PDUs.
KLQ-tSi""7 In the example illustrated in FIG. 3 described
above, the PDCP-PDU with the second highest priority is
divided into two PDCP-PDUs and thus, unless both the MAC-
PDU#1 and MAC-PDU#2 are correctly received on the receiving
side, the PDCP-PDU with the second highest priority may not
be reassembled. On the other hand, the PDCP-PDU with the
third highest priority may be obtained on the receiving
side if only the MAC-PDU#2 is correctly received. That is,
the PDCP-PDU with the second highest priority is less
likely to be transmitted to the receiving side correctly
than the PDCP-PDU with the third highest priority. This
could cause a frequent retransmission of a PDCP-PDU with a
higher priority as compared to the lower priority PDCP-PDU,
so that requirements of QoS corresponding to priorities may
not be satisfied.
[0014] The present invention has been made in view of
the above issues and an object thereof is to provide a
communication apparatus capable of improving transmission
efficiency of data and exercising reliable QoS control, a
transmission data generation program, and a transmission
data generation method.
MEANS FOR SOLVING PROBLEM
[n£^ To sol ve the problems and achieve the object, a
communication apparatus has a communication protocol
including two layers, and includes an acquisition unit that
acquires a size of free space enabling data multiplexing
and provided in each of a plurality of data transmission
units of a first layer; an allocation unit that allocates
to each of a plurality of pieces of data of a second layer
a contiguous sequence of the free space equal to each piece
of data in size and provided in one of the data
transmission units, among the free spaces whose size is
acquired by the acquisition unit; and a multiplexing unit
that multiplexes the plurality of pieces of data of the
second layer into the plurality of data transmission units
of the first layer according to allocation of the free
space by the allocation unit.
A transmission data generation program causes a
computer to operate as a communication apparatus having a
communication protocol including two layers, and includes
an acquisition step of acquiring a size of free space
provided in each of a plurality of data transmission units
of a first layer and capable of multiplexing data by the
computer; an allocation step of allocating to each of a
plurality of pieces of data of a second layer a contiguous
sequence of the free space equal to the each piece of data
in size and provided in one of the data transmission units
of the free space whose size is acquired in the acquisition
step by the computer; and a multiplexing step of
multiplexing the plurality of pieces of data of the second
layer into the plurality of data transmission units of the
first layer according to allocation of the free space by
the allocation step by the computer.
[<&&£T~f A transmission data generation method causes a
computer to function as a communication apparatus having a
communication protocol including two layers, and includes
an acquisition step of acquiring a size of free space
provided in each of a plurality of data transmission units
of a first layer and capable of multiplexing data by the
computer; an allocation step of allocating to each of a
plurality of pieces of data of a second layer a contiguous
sequence of the free space equal to the each piece of data
in size and provided in one of the data transmission units
of the free space whose size is acquired in the acquisition
step by the computer; and a multiplexing step of
multiplexing the plurality of pieces of data of the second
layer into the plurality of data transmission units of the
first layer according to allocation of the free space by
the allocation step by the computer.
[(!Q-4-8"l According to these embodiments, data division of
the second layer may be minimized and thus, the amount of
headers added in the second layer may be minimized. As a
result, radio resources consumed for transmitting headers
may be reduced so that transmission efficiency of data may
be improved. Moreover, by allocating free space to data in
descending order of priority, reliable QoS control may be
exercised by avoiding division of data with higher
priorities.
EFFECT OF THE INVENTION
[Q&k9J According to a communication apparatus, a
transmission data generation program, and a transmission
data generation method disclosed by the present
specification, transmission efficiency of data may be
improved and also reliable QoS control may be exercised.
BRIEF DESCRIPTION OF DRAWINGS
1&Q2&] FIG. 1 is a diagram illustrating a configuration
of Layer 2 in LTE.
FIG. 2 is a diagram illustrating correspondences of
data configurations between layers.
FIG. 3 is a diagram illustrating a concrete example of
transmission data generation in Layer 2.
FIG. 4 is a block diagram illustrating main components
of a transmission apparatus according to a first embodiment.
FIG. 5 is a flow chart illustrating a transmission
data generation method according to the first embodiment.
FIG. 6 is a diagram illustrating a concrete example of
the transmission data generation according to the first
embodiment.
FIG. 7 is a block diagram illustrating main components
of the transmission apparatus according to a second
embodiment.
FIG. 8 is a flow chart illustrating the transmission
data generation method according to the second embodiment.
FIG. 9 is a block diagram illustrating main components
of the transmission apparatus according to a third
embodiment.
FIG. 10 is a flow chart illustrating the transmission
data generation method according to the third embodiment.
EXPLANATIONS OF LETTERS OR NUMERALS
[OQ-2-tT 110-1 to 110-n PCDP processing unit
120-1 to 120-n RLC processing unit
121 Free space allocation unit
122 RLC-SDU buffer unit
123 Retransmission buffer unit
124 RLC-PDU creation unit
130, 200, 300 MAC processing unit
131, 201 Radio resource information acquisition unit
132 MAC-PDU creation unit
140 Layer 1 processing unit
150, 150-1, 150-2 Antenna
202 Free space size estimation unit
301 Scheduler unit
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0022] Embodiments of the present invention will be
described in detail below with reference to drawings.
[ 0,8-23] First Embodiment
FIG. 4 is a block diagram illustrating main components
of a transmission apparatus according to a first embodiment.
The transmission apparatus illustrated in FIG. 4 includes
PDCP processing units 110-1 to 110-n (n is an integer equal
to 1 or greater), RLC processing units 120-1 to 120-n, a
MAC processing unit 130, a Layer 1 processing unit 140, and
antennas 150-1 and 150-2.
[J3J3-2-47 The PDCP processing units 110-1 to 110-n each add
the header of the PDCP layer to an SDU by setting
transmission data as the SDU of the PDCP layer. Then, the
PDCP processing units 110-1 to 110-n output the PDCP-PDU,
obtained by adding the header, to the corresponding RLC
processing units 120-1 to 120-n. The PDCP processing units
110-1 to 110-n correspond to PDCP-PDUs whose priorities are
the first to the n-th respectively. In the present
embodiment, the PDCP processing unit 110-1 corresponds to
the PDCP-PDU with the highest priority and the PDCP
processing unit 110-n to the PDCP-PDU with the lowest
priority. Therefore, regarding the RLC processing units
120-1 to 120-n described later, the RLC processing unit
120-1 similarly corresponds to the RLC-PDU with the highest
priority and the RLC processing unit 120-n to the RLC-PDU
with the lowest priority.
[OJ&Tf The RLC processing units 120-1 to 120-n set PDCP-
PDUs output from the PDCP processing units 110-1 to 110-n
as SDU's of the RLC layer (hereinafter, referred to as "RLC-
SDU") and create RLC-PDUs by adding the header of the RLC
layer to the RLC-SDUs. At this point, the RLC processing
units 120-1 to 120-n create RLC-PDUs in such a way that
division of RLC-SDUs is reduced to a minimum based on free
space information notified from the MAC processing unit 130.
More specifically, each of the RLC processing units 120-1
to 120-n includes a free space allocation unit 121, an RLC-
SDU buffer unit 122, a retransmission buffer unit 123, and
an RLC-PDU creation unit 124.
£0J3-2^j Free space information indicates the free space
in a MAC-PDU that may be allocated to RLC-PDUs created by
the RLC processing units 120-1 to 120-n. When free space
information is notified from the MAC processing unit 130,
the free space allocation unit 121 allocates the free space
of a MAC-PDU to new RLC-SDUs or to RLC-PDUs already
transmitted, which are to be retransmitted (hereinafter,
these data units before the RLC layer header is added may
collectively be referred to simply as "RLC-SDU"). In this
example, the free space allocation unit 121 preferentially
allocates the free space of a MAC-PDU to an RLC-SDU which
may be allocated without division. If an RLC-PDU to be
retransmitted is held in the retransmission buffer unit 123,
the free space allocation unit 121 preferentially allocates
free space to the RLC-PDU to be retransmitted over a new
RLC-SDU. Further, if there is RLC layer control
information waiting to be transmitted, the free space
allocation unit 121 preferentially allocates free space to
the RLC layer control information waiting to be transmitted
over new or retransmission RLC-SDUs.
[OP^T^ The maximum free space size of a MAC-PDU is
defined by radio resources of, for example, the bandwidth
or power. In the present embodiment, the total size of the
space where data is multiplexed inside two MAC-PDUs
transmitted simultaneously by the antennas 150-1 and 150-2
becomes the maximum free space size of a MAC-PDU. If the
space of a MAC-PDU is already allocated to an RLC-SDU by
another RLC processing unit, the free space size of the
MAC-PDUs of which the RLC processing unit is notified
becomes smaller accordingly.
[0Q-2-8T The free space allocation unit 121 notifies the
RLC-SDU buffer unit 122 and the retransmission buffer unit
123, which temporarily store data or perform processing
thereon, of the allocation space of a MAC-PDU allocated to
RLC-SDU and also notifies the MAC processing unit 130
thereof.
[0029] C-SDU buffer unit 122 temporarily holds
PDCP-PDUs output from the PDCP processing units 110-1 to
110-n as new RLC-SDUs. Then, the RLC-SDU buffer unit 122
outputs a new RLC-SDU in accordance with the allocation
space notified from the free space allocation unit 121.
That is, if the size of allocation space notified from the
free space allocation unit 121 is equal to the size of one
RLC-SDU or more, the RLC-SDU buffer unit 122 outputs an
entire new RLC-SDU to the RLC-PDU creation unit 124. On
the other hand, if the size of allocation space notified
from the free space allocation unit 121 is less than the
size of one RLC-SDU, the RLC-SDU buffer unit 122 divides
the new RLC-SDU and outputs a portion of the RLC-SDU equal
to the size of allocation space notified from the free
space allocation unit 121 to the RLC-PDU creation unit 124.
[O&3-0T However, if there is any RLC-PDU to be
retransmitted or control information to be preferentially
transmitted over the new RLC-SDU, the RLC-SDU buffer unit
122 does not output any RLC-SDU because the RLC-PDU to be
retransmitted or control information is preferentially
transmitted.
[ftp^PT The retransmission buffer unit 123 temporarily
holds RLC-PDUs transmitted from the antennas 150-1/150-2
and multiplexed into MAC-PDUs in preparation for
retransmission. The retransmission buffer unit 123 outputs
an RLC-PDU to be retransmitted in accordance with the
allocation space notified from the free space allocation
unit 121. That is, if the size of allocation space
notified from the free space allocation unit 121 is equal
to the size of one RLC-SDU or more, the retransmission
buffer unit 123 outputs the whole RLC-PDU to be
retransmitted to the RLC-PDU creation unit 124. On the
other hand, if the size of allocation space notified from
the free space allocation unit 121 is less than the size of
one RLC-PDU to be retransmitted, the retransmission buffer
unit 123 divides the RLC-PDU and outputs a portion of the
RLC-PDU equal to the size of allocation space to the RLC-
PDU creation unit 124.
[Q^rS^] However, if there is control information to be
preferentially transmitted over an RLC-PDU to be
retransmitted, the retransmission buffer unit 123 does not
output any RLC-PDU to be retransmitted because the control
information is preferentially transmitted.
\£&5^ The RLC-PDU creation unit 124 adds an appropriate
RLC layer header to an RLC-SDU output from the RLC-SDU
buffer unit 122 or the retransmission buffer unit 123 to
create an RLC-PDU. If an RLC-PDU to be retransmitted is
divided to fit to the size of allocation space and a
portion thereof is output from the retransmission buffer
unit 123 as a new RLC-SDU, the RLC-PDU creation unit 124
recreates a RLC layer header indicating that the RLC-PDU
has been divided anew and adds the header thereto. Then,
the RLC-PDU creation unit 124 outputs the created RLC-PDU
to the MAC processing unit 130.
[003-4^ The MAC processing unit 130 decides the size of
free space for a MAC-PDU based on radio resources of, for
example, the bandwidth or power available for transmission
of data and allocation conditions of space of a MAC-PDU by
each of the RLC processing units 120-1 to 120-n. The MAC
processing unit 130 notifies the RLC processing units 120-1
to 120-n of the size of the free space as free space
information. The MAC processing unit 130 creates MAC-PDUs
by multiplexing RLC-PDUs output from the RLC processing
units 120-1 to 120-n. More specifically, the MAC
processing unit 130 includes a radio resource information
acquisition unit 131 and a MAC-PDU creation unit 132.
[0£3-5"] The radio resource information acquisition unit
131 acquires information about radio resources available
for transmission of data from each of the antennas 150-1
and 150-2 to decide the maximum free space size of a MAC-
PDU transmitted from the two antennas based on the radio
resources information. When allocation space is notified
from the free space allocation unit 121 of the RLC
processing units 120-1 to 120-n, the radio resource
information acquisition unit 131 subtracts the size of the
allocation space from the size of free space for a MAC-PDU
to decide the new free space size for the MAC-PDU. Then,
the radio resource information acquisition unit 131 outputs
free space information containing the newly decided free
space size to the free space allocation unit 121 of the RLC
processing unit with the highest priority among the RLC
processing units that have not been notified of the free
space information indicating the size of free space of a
MAC-PDU.
[G^©-3-6f For example, if none of the RLC processing units
120-1 to 120-n was notified of free space information, the
radio resource information acquisition unit 131 notifies
the free space allocation unit 121 of the RLC processing
unit 120-1 of the maximum size of the free space for a MAC-
PDU. After the RLC processing unit 120-1 is notified of
the free space information, the radio resource information
acquisition unit 131 subtracts the size of allocation space
allocated to the RLC-PDU in the RLC processing unit 120-1
from the maximum size of free space and notifies the free
space allocation unit 121 of the RLC processing unit 120-2
of the remaining size of the free space.
LStfS?] The MAC-PDU creation unit 132 multiplexes the
RLC-PDU output from the RLC-PDU creation unit 124 of each
of the RLC processing units 120-1 to 120-n as a MAC-SDU and
adds the MAC layer header to create a MAC-PDU. At this
point, the MAC-PDU creation unit 132 multiplexes RLC-PDUs
according to the allocation space notified from the free
space allocation unit 121 of each of the RLC processing
units 120-1 to 120-n. Thus, two MAC-PDUs created by the
MAC-PDU creation unit 132 contain a minimum amount of
divided RLC-SDUs so that the space occupied by headers of
the RLC layer in MAC-PDUs is minimized.
[003-8*] The Layer 1 processing unit 140 controls the
bandwidth and power in the antennas 150-1 and 150-2 and
provides radio resource information to the radio resource
information acquisition unit 131 of the MAC processing unit
130. The Layer 1 processing unit 140 simultaneously
transmits the two MAC-PDUs created by the MAC-PDU creation
unit 132 of the MAC processing unit 130 from the different
antennas 150-1 and 150-2. That is, the Layer 1 processing
unit 140 performs Multi Input Multi Output (MIMO)
communication that simultaneously transmits different data
from a plurality of antennas. MAC-PDUs are simultaneously
transmitted from the two antennas 150-1 and 150-2 in the
present embodiment, but MAC-PDUs may simultaneously be
transmitted from three antennas or more. In such a case,
the total of the free space of as many MAC-PDUs as the
number of antennas becomes the space to be allocated to
RLC-SDUs in the RLC processing units 120-1 to 120-n.
[Q£2r*f\ A transmission data generation method by a
transmission apparatus configured similarly as the
transmission apparatus described above will be described
with reference to the flow chart in FIG. 5.
[&&4,QT~ Radio resources in each of the antennas 150-1 and
150-2 constantly change and thus, the radio resource
information acquisition unit 131 acquires radio resource
information concerning each of the antennas 150-1 and 150-2
via the Layer 1 processing unit 140 (step S101). Then, the
radio resource information acquisition unit 131 decides the
maximum size of the free space of the MAC-PDU corresponding
to each of the antennas 150-1 and 150-2 from the radio
resource information. The RLC processing unit with the
highest priority among the RLC processing units not already
notified of the free space information is notified of the
free space information decided by the radio resource
information acquisition unit 131 and indicating the size of
free space (step S102). Here, no RLC processing unit has
been notified of free space information and thus, the free
space allocation unit 121 of the RLC processing unit 120-1
with the highest priority is notified of the free space
information indicating the maximum size of the free space.
[0041] Then, the free space allocation unit 121 of the
RLC processing unit 120-1 allocates a portion of the size
of free space to the RLC-SDU of the RLC processing unit
120-1 (step S103). At this point, a contiguous sequence of
free space in one MAC-PDU is selected by the free space
allocation unit 121 as the allocation space of RLC-SDU and
the RLC-SDU buffer unit 122, the retransmission buffer unit
123, and the MAC processing unit 130 are notified of the
selected allocation space so that the RLC-SDU is allocated
to one MAC-PDU without being divided.
[QQJ&tf When the RLC-SDU buffer unit 122 and the
retransmission buffer unit 123 are notified of the
allocation space, a new or retransmission RLC-SDU is output
to the RLC-PDU creation unit 124 and the RLC-PDU creation
unit 124 creates an RLC-PDU by adding an appropriate header
of the RLC layer to the RLC-SDU (step S104). At this point,
an RLC-PDU is created by preferentially inputting into the
RLC-PDU creation unit 124 RLC-PDUs to be retransmitted over
new RLC-SDUs, and control information over RLC-PDUs to be
retransmitted.
When the radio resource information acquisition
unit 131 of the MAC processing unit 130 is notified of the
allocation space, the radio resource information
acquisition unit 131 determines whether allocation of free
space of MAC-PDUs for all the RLC processing units 120-1 to
120-n is completed (step S105). Here, free space has been
allocated for only the RLC processing unit 120-1 and thus,
the description below will continue by assuming that
allocation of free space for all the RLC processing units
is not completed (No in step S105).
In this example, the radio resource information
acquisition unit 131 subtracts the size of the allocated
space for the RLC processing unit 120-1 from the maximum
size of the free space for the MAC-PDU to calculate a new
free space size for the MAC-PDUs. Then, the RLC processing
unit with the highest priority among the RLC processing
units not previously notified of free space information is
notified of the free space information indicating the
calculated size of free space (step S102). Here, only the
RLC processing unit 120-1 has been notified of the free
space information and thus, the free space allocation unit
121 of the RLC processing unit 120-2 with the second
highest priority is notified of the free space information
indicating the newly calculated size of the free space.
[0J}4-3'f Then, the free space allocation unit 121 of the
RLC processing unit 120-2 allocates a portion of the free
space size to the RLC-SDU of the RLC processing unit 120-2
(step S103). At this point, a contiguous sequence of free
space in one MAC-PDU is selected by the free space
allocation unit 121 as the allocation space for the RLC-SDU
and the RLC-SDU buffer unit 122, the retransmission buffer
unit 123, and the MAC processing unit 130 are notified of
the selected allocation space so that the RLC-SDU is
allocated to one MAC-PDU without being divided. If,
however, sufficient free space to allocate to the RLC-SDU
is not available in either of the two MAC-PDUs, space to be
allocated to the divided RLC-SDUs is reserved in each of
the MAC-PDUs.
[O^Kf After the RLC-SDU buffer unit 122 and the
retransmission buffer unit 123 are notified of the
allocation space, a new or retransmission RLC-SDU is output
to the RLC-PDU creation unit 124 and the RLC-PDU creation
unit 124 creates an RLC-PDU by adding an appropriate RLC
layer header of the RLC layer to the RLC-SDU (step S104).
If the notified size of the allocation space is small and
division of the RLC-SDU becomes necessary, the RLC-SDU is
divided by the RLC-SDU buffer unit 122 or the
retransmission buffer unit 123 to fit to the size of
allocation space and the divided data is output to the RLC-
PDU creation unit 124. Then, the RLC-PDU creation unit 124
adds an appropriate RLC layer header to each piece of data
to create a plurality of RLC-PDUs corresponding to one RLC-
SDU.
[0-&C7] When the radio resource information acquisition
unit 131 of the MAC processing unit 130 is notified of the
allocation space, the radio resource information
acquisition unit 131 determines whether allocation of free
space of MAC-PDUs for all the RLC processing units 120-1 to
120-n is completed (step S105). Here, free space has been
allocated for all the RLC processing units 120-1 to 120-n
and thus, the description below will continue by assuming
that allocation of free space for all the RLC processing
units is completed (Yes in step S105).
[00-4-81 The RLC-PDU created by the RLC-PDU creation unit
124 of each of the RLC processing units 120-1 to 120-n is
output to the MAC-PDU creation unit 132 of the MAC
processing unit 130 and the MAC-PDU creation unit 132
creates MAC-PDUs (step S106). That is, the MAC-PDU
creation unit 132 multiplexes each RLC-PDU as a MAC-SDU and
adds the header of the MAC layer to the whole of a
plurality of MAC-SDUs. In the present embodiment, free
space of the two MAC-PDUs corresponding to the two antennas
150-1 and 150-2 is allocated to RLC-PDUs of the RLC
processing units 120-1 to 120-n and thus, the MAC-PDU
creation unit 132 creates two MAC-PDUs.
[0Q>§^ Since free space of MAC-PDUs is allocated in such
a way that division of RLC-SDU is minimized in the present
embodiment, the number of MAC-SDUs contained in the created
two MAC-PDUs is minimized. In other words, the proportion
of space occupied by headers of the RLC layer in the two
MAC-PDUs is reduced to a minimum so that more data may be
multiplexed into the MAC-PDUs. As a result, transmission
efficiency of data is improved. Moreover, the RLC
processing unit allocates free space of MAC-PDUs to RLC-
PDUs in descending order of priority and thus, RLC-SDUs
with an increasingly higher priority are less likely to be
divided. As a result, important data to be prioritized is
less likely to be transmitted across a plurality of MAC-
PDUs so that QoS control may reliably be exercised.
[p&StTT^ The two MAC-PDUs created by the MAC-PDU creation
unit 132 are output to the Layer 1 processing unit 140 and
simultaneously transmitted from the two antennas 150-1 and
150-2 by transmission processing of Layer 1 being performed
thereon by the Layer 1 processing unit 140 (step S107). In
the present embodiment, an RLC-SDU with a higher priority
is multiplexed into one MAC-PDU without being divided and
thus, if the MAC-PDU transmitted from one antenna is
correctly received on the receiving side, the whole RLC-SDU
with a higher priority may be acquired. On the other hand,
an RLC-SDU with a lower priority may be multiplexed into
two MAC-PDUs after being divided and thus, unless both MAC-
PDUs transmitted from the two antennas are correctly
received, the whole RLC-SDU with a lower priority may not
be acquired on the receiving side.
Next, a concrete example of transmission data
generation according to the present embodiment will be
described with reference to FIG. 6. For the below example,
a case when a new RLC-SDU is transmitted is considered and
it is assumed that there is no transmission of an RLC-PDU
to be retransmitted or control information. More
specifically, an example will be described a case when a
new RLC-SDU is held in the RLC-SDU buffer unit 122 in each
of RLC#1 to #4 corresponding to four RLC processing units
and these RLC-SDUs are simultaneously transmitted after
being multiplexed into MAC-PDU#1 and #2 corresponding to
the two antennas 150-1 and 150-2. It is assumed that the
RLC-SDU of the RLC#1 has the highest priority of data
followed by the RLC-SDU of the RLC#2, the RLC-SDU of the
RLC#3, and the RLC-SDU of the RLC#4.
[OD-SrZT The RLC#1 has the highest priority and thus, the
maximum free space of the two MAC-PDU#1 and #2 is notified
from the radio resource information acquisition unit 131 as
free space information. The RLC#1 may freely allocate the
whole maximum free space of the two MAC-PDU#1 and #2 to the
RLC-SDU and so allocates head space of the MAC-PDU#1 to the
RLC-SDU so that the RLC-SDU is not divided. Therefore, as
illustrated in FIG. 6, the RLC-PDU#1 created by the RLC#1
is multiplexed into the head space of the MAC-PDU#1.
[QQ&S'l After deciding the allocation space to the RLC-
SDU, the RLC#1 notifies the radio resource information
acquisition unit 131 of the decided allocation space.
After receiving the notification, the radio resource
information acquisition unit 131 sets new free space by
excluding the space corresponding to the RLC-PDU#1.
[0Q5r4T Thus, the RLC#2 with the second highest priority
is notified of free space excluding the space into which
RLC-PDU#1 is multiplexed from the maximum free space of the
two MAC-PDU#1 and #2 as free space information. The RLC#2
may allocate the notified free space to the RLC-SDU and so
allocates head space of the MAC-PDU#2 to the RLC-SDU so
that the RLC-SDU is not divided. That is, the MAC-PDU#1
does not have sufficient free space remaining to be
allocated to the RLC-SDU of the RLC#2 and so the head space
of the MAC-PDU#2 is allocated to the RLC-SDU to avoid
division of the RLC-SDU. Therefore, as illustrated in FIG.
6, the RLC-PDU created by the RLC#2 is to be multiplexed
into the head space of the MAC-PDU#2 as RLC-PDU#3.
[QJ3-5-!?]' After deciding the allocation space to the RLC-
SDU, the RLC#2 notifies the radio resource information
acquisition unit 131 of the decided allocation space.
After receiving the notification, the radio resource
information acquisition unit 131 sets new free space by
excluding the space corresponding to the RLC-PDU#3.
[OQ&lff Thus, the RLC#3 with the third highest priority
is notified of free space excluding the space into which
RLC-PDU#1 and #3 are multiplexed from the maximum free
space of the two MAC-PDU#1 and #2 as free space information.
The RLC#3 may allocate the notified free space to the RLC-
SDU and so allocates the space immediately after the space
into which the RLC-PDU#1 of the MAC-PDU#1 is multiplexed,
to the RLC-SDU, so that the RLC-SDU is not divided. That
is, the MAC-PDU#1 has sufficient free space remaining to be
allocated to the RLC-SDU of the RLC#3 and so the space
immediately after the RLC-PDU#1 is allocated to the RLC-SDU
of the RLC#3. Therefore, as illustrated in FIG. 6, the
RLC-PDU created by the RLC#3 is multiplexed into the space
immediately after the RLC-PDU#1 as RLC-PDU#2.
[QjQ-57] After deciding the allocation space to the RLC-
SDU, the RLC#3 notifies the radio resource information
acquisition unit 131 of the decided allocation space.
After receiving the notification, the radio resource
information acquisition unit 131 sets new free space by-
excluding the space corresponding to the RLC-PDU#2.
[0££#T Thus, the RLC#4 with the fourth highest priority
is notified of free space excluding the space into which
RLC-PDU#1 to #3 are multiplexed from the maximum free space
of the two MAC-PDU#1 and #2 as free space information. The
RLC#4 may allocate the notified free space to the RLC-SDU
and so searches for free space that may be allocated
without dividing the RLC-SDU. However, sufficient free
space to multiplex the RLC-SDU does not remain and so the
remaining free space of the MAC-PDU#2 is allocated to a
portion of the RLC-SDU. That is, only the MAC-PDU#2 has
free space remaining that may be allocated to a portion of
the RLC-SDU of the RLC#4 and so the space immediately after
the RLC-PDU#3 is allocated to a portion of the RLC-SDU of
the RLC#4. Therefore, the RLC#4 divides the RLC-SDU by
fitting to the size of the allocation space and creates an
RLC-PDU from the obtained portion of the RLC-SDU to
multiplex the RLC-PDU, as illustrated in FIG. 6, into the
space immediately after the RLC-PDU#3 as RLC-PDU#4.
[0Q£r?f] According to the present embodiment, as described
above, if the size of free space of a plurality of MAC-PDUs
transmitted simultaneously from a plurality of antennas is
decided from radio resources, free space of the size that
allows multiplexing without dividing the RLC-SDU is
reserved for the RLC processing unit in descending order of
priority. Thus, the number of divided RLC-SDUs may be
minimized and so the number of RLC-PDUs created by adding
headers of the RLC layer may be minimized. As a result,
radio resources consumed for transmitting headers of the
RLC layer may be reduced and also transmission efficiency
of data may be improved. RLC-SDUs with an increasingly
higher priority are less likely to be divided and thus,
multiplexing of data with high demanded QoS across a
plurality of MAC-PDUs becomes less likely so that reliable
QoS control may be exercised.
Second Embodiment
A second embodiment of the present invention is
characterized in that the size of free space of a MAC-PDU
that will be transmitted in the future is estimated and
free space of a plurality of MAC-PDUs transmitted
chronologically is allocated to RLC-SDUs in descending
order of priority.
[p&Gl] FIG. 7 is a block diagram illustrating main
components of the transmission apparatus according to the
present embodiment. In FIG. 7, the same reference numerals
are attached to the same components as those in FIG. 4 and
a description thereof is not repeated here. The
transmission apparatus illustrated in FIG. 7 includes a MAC
processing unit 200, instead of the MAC processing unit 130
of the transmission apparatus illustrated in FIG. 4 and
includes only one antenna 150. The MAC processing unit 200
has a configuration in which, instead of the radio resource
information acquisition unit 131 of the MAC processing unit
130, a radio resource information acquisition unit 201 and
to which a free space size estimation unit 202 is added.
[0062] The radio resource information acquisition unit
201 acquires information about radio resources currently
available for data transmission from the antenna 150 and
based on the radio resource information, decides the size
of free space of the MAC-PDU currently to be transmitted
from the antenna 150. When the size of free space of a
MAC-PDU that will be transmitted in the future from the
antenna 150 is notified from the free space size estimation
unit 202, the radio resource information acquisition unit
201 adds up the size of free space of the MAC-PDU currently
to be transmitted and that of free space of the MAC-PDU
that will be transmitted in the future to decide the
maximum size of free space.
Further, when the allocation space is notified
from the free space allocation unit 121 of the RLC
processing units 120-1 to 120-n, the radio resource
information acquisition unit 201 decides the new size of
free space of the MAC-PDU by subtracting the size of
allocation space from the size of free space of the MAC-PDU.
Then, the radio resource information acquisition unit 201
outputs free space information containing the newly decided
size of free space to the free space allocation unit 121 of
the RLC processing unit with the highest priority among the
RLC processing units not already notified of the free space
information indicating the size of free space of the MAC-
PDU.
The free space size estimation unit 202 estimates
the size of free space of the MAC-PDU that will be
transmitted in the future based on channel quality
information (CQI) reported from a reception apparatus (not
illustrated) to be a transmission destination of the MAC-
PDU. More specifically, the free space size estimation
unit 202 forecasts CQI that will be received next time and
thereafter from a history of CQI received to date. The CQI
indicates channel quality between the transmission
apparatus and the reception apparatus (not illustrated) and
does not normally change significantly in a short time.
Therefore, CQI that will be received next time and
thereafter may be forecast relatively correctly from a
history of CQI to date.
Then, the free space size estimation unit 202
estimates the size of free space of one MAC-PDU or more
transmitted subsequent to the MAC-PDU whose size of free
space has been decided by the radio resource information
acquisition unit 201 from forecast results of CQI. The
free space size estimation unit 202 also notifies the radio
resource information acquisition unit 201 of the size of
free space of the MAC-PDU obtained by estimation. The free
space size estimation unit 202 need not necessarily
estimate the size of free space of MAC-PDUs that will be
transmitted in the future based on CQI. That is, the free
space size estimation unit 202 may estimate the size of
free space of MAC-PDUs in the future based on, for example,
a history of the size of free space of MAC-PDUs to date.
[OQJerf)] Next, a transmission data generation method by a
transmission apparatus similarly configured as described
above will be described with reference to the flow chart in
FIG. 8. In FIG. 8, the same reference numerals are
attached to the same steps as those in FIG. 5 and a
description thereof is not repeated here.
[Q£-6T] Radio resources in the antenna 150 constantly
change and thus, the radio resource information acquisition
unit 201 acquires radio resource information concerning the
antenna 150 via the Layer 1 processing unit 140 (step S101).
Then, the radio resource information acquisition unit 201
decides the size of free space of the MAC-PDU transmitted
currently from the antenna 150 from the radio resource
information.
The free space size estimation unit 202 estimates
the size of free space of MAC-PDUs that will be transmitted
in the future from the antenna 150 based on CQI (step S201).
That is, the free space size estimation unit 202 estimates
the size of free space of one MAC-PDU or more transmitted
subsequent to the MAC-PDU whose size of free space has been
decided by the radio resource information acquisition unit
201 from the condition of channel quality to date. The
free space size estimation unit 202 notifies the radio
resource information acquisition unit 201 of the estimated
size of free space of MAC-PDUs and the radio resource
information acquisition unit 201 adds up the size of free
space of a predetermined number of MAC-PDUs transmitted
currently or hereinafter to decide the maximum size of free
space. The RLC processing unit with the highest priority
among the RLC processing units not notified of free space
information is notified of the free space information
indicating the size of free space decided by the radio
resource information acquisition unit 201 (step S102).
[O^Q-eiT] Then, the free space allocation unit 121 of the
RLC processing unit notified of the free space information
allocates a portion of the size of free space to RLC-SDUs
(step S103). At this point, the free space allocation unit
121 selects a contiguous sequence of free space in one MAC-
PDU as the allocation space of RLC-SDU so that one MAC-PDU
is allocated without the RLC-SDU being divided and notifies
the RLC-SDU buffer unit 122, the retransmission buffer unit
123, and the MAC processing unit 200 of the selected
allocation space.
[^QjQ-TOT After the RLC-SDU buffer unit 122 and the
retransmission buffer unit 123 are notified of the
allocation space, a new or retransmission RLC-SDU is output
to the RLC-PDU creation unit 124 and the RLC-PDU creation
unit 124 creates an RLC-PDU by adding an appropriate RLC
layer header to the RLC-SDU (step S104).
[0071] the radio resource information acquisition
unit 201 of the MAC processing unit 200 is notified of the
allocation space, the radio resource information
acquisition unit 201 determines whether allocation of free
space of MAC-PDUs for all the RLC processing units 120-1 to
120-n is completed (step S105). Hereinafter, like in the
first embodiment, the allocation of free space of MAC-PDUs
to RLC-SDUs is carried out in all the RLC processing units
120-1 to 120-n.
[0072] n the allocation of free space is completed in
all the RLC processing units (Yes in step S105), each RLC-
PDU created by the RLC-PDU creation unit 124 of the RLC
processing units 120-1 to 120-n is output to the MAC-PDU
creation unit 132 of the MAC processing unit 200 and the
MAC-PDU creation unit 132 creates MAC-PDUs (step S106).
Here, not only is the MAC-PDU to be transmitted currently
created, but also MAC-PDUs in the future whose size of free
space is estimated by the free space size estimation unit
202 are created. MAC-PDUs created by the MAC-PDU creation
unit 132 are output to the Layer 1 processing unit 140 and
successively transmitted from the antenna 150 by
transmission processing of Layer 1 being performed by the
Layer 1 processing unit 140 (step S107).
[Q£L?-3^ In the present embodiment, an RLC-SDU with a
higher priority may be multiplexed into one MAC-PDU without
being divided and thus, if one MAC-PDU is correctly
received on the receiving side, the whole RLC-SDU with a
higher priority may be acquired. On the other hand, an
RLC-SDU with a lower priority may be multiplexed into two
MAC-PDUs after being divided and thus, unless both MAC-PDUs
transmitted in different timing are correctly received on
the receiving side, the whole RLC-SDU with a lower priority
may not be acquired. As a result, important data to be
prioritized will not be transmitted across a plurality of
MAC-PDUs so that QoS control may reliably be exercised.
[0n-7-*rT> According to the present embodiment, as described
above, if the size of free space of a plurality of MAC-PDUs
transmitted in different timing is estimated based on radio
resources and channel quality, free space of the size that
allows multiplexing without dividing the RLC-SDU is
reserved for the RLC processing unit in descending order of
priority. Thus, the number of divided RLC-SDUs may be
minimized in a transmission apparatus including one antenna
and so the number of RLC-PDUs created by adding headers of
the RLC layer may be minimized. As a result, radio
resources consumed for transmitting headers of the RLC
layer may be prevented from increasing and also
transmission efficiency of data may be improved. RLC-SDUs
with an increasingly higher priority are less likely to be
divided and thus, multiplexing of data with high demanded
QoS across a plurality of MAC-PDUs becomes less likely so
that reliable QoS control may be exercised.
[p&?3] Third Embodiment
A third embodiment of the present invention is
characterized in that, instead of allocating free space of
MAC-PDUs to RLC-SDUs in the RLC layer, scheduling of
deciding allocation of free space is carried out in the MAC
layer.
[Q^Tiof FIG. 9 is a block diagram illustrating main
components of the transmission apparatus according to the
present embodiment. In FIG. 9, the same reference numerals
are attached to the same components as those in FIG. 4 and
a description thereof is not repeated here. The
transmission apparatus illustrated in FIG. 9 includes a MAC
processing unit 300, instead of the MAC processing unit 130
of the transmission apparatus illustrated in FIG. 4. The
MAC processing unit 300 includes a scheduler unit 301,
instead of the radio resource information acquisition unit
131 of the MAC processing unit 130.
[Qprf] The scheduler unit 301 monitors the RLC-SDU
buffer unit 122 and the retransmission buffer unit 123 of
each of the RLC processing units 120-1 to 120-n to detect
the quantity of RLC-SDU(s) holding in the RLC layer. That
is, the scheduler unit 301 acquires the amount of data
holding in the RLC layer to be transmitted such as a new or
retransmission RLC-SDU waiting to be transmitted and
control information.
The scheduler unit 301 also acquires information
about radio resources available for data transmission from
each of the antennas 150-1 and 150-2 to decide the maximum
size of free space of MAC-PDUs transmitted from the two
antennas based on the information about radio resources.
[QS&4] Then, the scheduler unit 301 carries out
scheduling to allocate free space of MAC-PDUs to data
holding in the RLC layer held by the RLC processing units
120-1 to 120-n. At this point, the scheduler unit 301
allocates free space of MAC-PDUs that may be allocated
without dividing data to holding data holding in the RLC
processing unit in descending order of priority.
[OOtfOl The scheduler unit 301 notifies the RLC-SDU
buffer unit 122 and the retransmission buffer unit 123 in
each of the RLC processing units 120-1 to 120-n of the
allocation space of the MAC-PDU allocated to holding data
in each of the RLC processing units 120-1 to 120-n and also
notifies the MAC-PDU creation unit 132 thereof.
[0034] A transmission data generation method by a
transmission apparatus similarly configured as described
above will be described with reference to the flow chart in
FIG. 10.
4-0-013"2Sj Radio resources in each of the antennas 150-1 and
150-2 constantly change and thus, the scheduler unit 301
acquires radio resource information concerning each of the
antennas 150-1 and 150-2 via the Layer 1 processing unit
140 (step S101). Then, the scheduler unit 301 decides the
maximum size of free space of the MAC-PDU corresponding to
each of the antennas 150-1 and 150-2 from the radio
resource information.
[0Q-6T3] The scheduler unit 301 acquires the amount of
control information of RLC-PDUs and the RLC layer held in
the RLC-SDU buffer unit 122 and the retransmission buffer
unit 123 of the RLC processing units 120-1 to 120-n.
Accordingly, the amount of holding data in the RLC layer
waiting to be transmitted in the RLC processing units 120-1
to 120-n is acquired (step S301).
[0P#3f] After the maximum size of free space of MAC-PDUs
is decided and the amount of holding data in the RLC layer
is acquired, the scheduler unit 301 carries out scheduling
to allocate free space of MAC-PDUs to holding data of each
of the RLC processing units 120-1 to 120-n (step S302) .
That is, the scheduler unit 301 first allocates a portion
of free space to holding data in the RLC processing unit
120-1 with the highest priority. At this point, a
contiguous sequence of free space in one MAC-PDU is
selected as the allocation space so that holding data in
the RLC processing unit 120-1 is allocated to one MAC-PDU
without being divided.
[0Q81T] After the allocation space to the holding data in
the RLC processing unit 120-1 being selected, the scheduler
unit 301 subtracts the size of the allocation space to the
holding data in the RLC processing unit 120-1 from the
maximum size of free space of the MAC-PDU to calculate the
new size of free space of the MAC-PDU. Then, the scheduler
unit 301 allocates a portion of new free space to holding
data in the RLC processing unit 120-2 with the second
highest priority. Also in this case, a contiguous sequence
of free space in one MAC-PDU is selected as the allocation
space of RLC-SDU so that holding data in the RLC processing
unit 120-2 is allocated to one MAC-PDU without being
divided. If, however, sufficient free space to allocate to
holding data is available in none of the two MAC-PDUs,
space to be allocated to the divided holding data is
reserved in each of the MAC-PDUs.
[00-8-61 Hereinafter, free space of the MAC-PDUs is
allocated to holding data of all the RLC processing units
120-1 to 120-n in descending order of priority. When free
space is allocated to all holding data, the RLC-SDU buffer
unit 122 or the retransmission buffer unit 123 of the RLC
processing units 120-1 to 120-n is notified of the
allocation space allocated to each piece of holding data
(step S303) .
[0P8T\ When the RLC-SDU buffer unit 122 and the
retransmission buffer unit 123 is notified of the
allocation space in each of the RLC processing units 120-1
to 120-n, a new or retransmission RLC-SDU is output to the
RLC-PDU creation unit 124 and the RLC-PDU creation unit 124
creates an RLC-PDU by adding an appropriate RLC layer
header to the RLC-SDU (step S104). If the notified size of
allocated space is too small and division of RLC-SDU
becomes necessary, the RLC-SDU buffer unit 122 or the
retransmission buffer unit 123 divides the RLC-SDU to fit
to the size of allocation space and divided data is output
to the RLC-PDU creation unit 124. Then, the RLC-PDU
creation unit 124 creates a plurality of RLC-PDUs
corresponding to one RLC-SDU by adding appropriate RLC
layer headers to the respective data.
[008^] Each RLC-PDU created by the RLC-PDU creation unit
124 of the RLC processing units 120-1 to 120-n is output to
the MAC-PDU creation unit 132 of the MAC processing unit
300 and the MAC-PDU creation unit 132 creates MAC-PDUs
(step S106). The MAC-PDUs created by the MAC-PDU creation
unit 132 are output to the Layer 1 processing unit 140 and
simultaneously transmitted each from the antennas 150-1 and
150-2 by transmission processing of Layer 1 being performed
by the Layer 1 processing unit 140 (step S107).
In the present embodiment, holding data of an RLC
processing unit with a higher priority is multiplexed into
one MAC-PDU without being divided and thus, if an MAC-PDU
transmitted from one antenna is correctly received on the
receiving side, the whole data of the RLC processing unit
with a higher priority may be acquired. On the other hand,
holding data of an RLC processing unit with a lower
priority may be multiplexed into two MAC-PDUs after being
divided. Thus, unless both MAC-PDUs transmitted from two
antennas are correctly received on the receiving side, the
whole data of the RLC processing unit with a lower priority
may not be acquired. As a result, important data to be
prioritized will not be transmitted across a plurality of
MAC-PDUs so that QoS control may reliably be exercised.
[00,90] According to the present embodiment, as described
above, if the size of free space of a plurality of MAC-PDUs
transmitted simultaneously from a plurality of antennas is
decided from radio resources, the amount of holding data in
each RLC layer is acquired in the MAC layer and free space
of the size that allows multiplexing without dividing the
holding data is reserved for the holding data in the RLC
layer in descending order of priority. Thus, the number of
pieces of data in the RLC layer transmitted after being
divided may be minimized and so the number of RLC-PDUs
created by adding headers of the RLC layer may be minimized.
As a result, radio resources consumed for transmitting
headers of the RLC layer may be prevented from increasing
and also transmission efficiency of data may be improved.
Data of the RLC layer with an increasingly higher priority
is less likely to be divided and thus, multiplexing of data
with high demanded QoS across a plurality of MAC-PDUs
becomes less likely so that reliable QoS control may be
exercised.
In each of the above embodiments, a case when a
plurality of SDUs of an upper layer, the RLC layer, is
multiplexed into PDUs of a lower layer, the MAC layer, has
been described, but the present invention is not limited to
such a case and may be applied also to between layers other
than the RLC layer and the MAC layer. That is, when a
plurality of pieces of data of an upper layer is
multiplexed into free space in predetermined data
transmission units of a lower layer, effects similar to
those of each of the above embodiments may be achieved by
allocating free space in data transmission units to each
piece of data so that division of each piece of data is
avoided if possible. In this case, reliable QoS control
may be exercised by allocating free space to data in
descending order of priority.
[09^21 A transmission apparatus and a transmission data
generation method similar to those described in each of the
above embodiments can be realized by generating a
transmission data generation program describing the
transmission data generation method described in each of
the above embodiments in a computer executable form and
causing the computer to execute the transmission data
generation program. In this case, a computer readable
recording medium can be caused to store the transmission
data generation program to introduce the transmission data
generation program into the computer by using the recording
medium.
Further, in each of the above embodiments, the
RLC layer and the MAC layer of Layer 2 in LTE have been
described as an upper layer and a lower layer respectively,
but the present invention is not limited to such an example
and can be widely applied when a plurality of pieces of
data in an upper layer is multiplexed into a plurality of
data transmission units of a lower layer in various
communication protocols and communication methods.
CLAIMS
1. A communication apparatus having a communication
protocol including two layers, the communication apparatus
comprising:
an acquisition unit that acquires a size of free space
enabling data multiplexing and provided in each of a
plurality of data transmission units of a first layer;
an allocation unit that allocates to each of a
plurality of pieces of data of a second layer a contiguous
sequence of the free space equal to each piece of data in
size and provided in one of the data transmission units,
among the free spaces whose size is acquired by the
acquisition unit; and
a multiplexing unit that multiplexes the plurality of
pieces of data of the second layer into the plurality of
data transmission units of the first layer according to
allocation of the free space by the allocation unit.
2. The communication apparatus according to claim 1,
wherein the allocation unit allocates the free space to the
data in descending order of priority when allocating the
free space to each of the plurality of pieces of data of
the second layer.
3. The communication apparatus according to claim 1,
wherein the allocation unit allocates a free space across a
plurality of data transmission units to the data when no
contiguous sequence of the free space equal to one of
pieces of data of the second layer in size is available in
one data transmission unit.
4. The communication apparatus according to claim 1,
wherein the allocation unit includes a plurality of data
distinct processing units provided corresponding to each of
the plurality of pieces of data of the second layer, each
data distinct processing unit allocating a free space to
one piece of data corresponding to the each data distinct
processing unit from among the free space notified from the
acquisition unit, and
the acquisition unit acquires a new free space by
excluding allocation space already allocated from the free
space each time the free space is allocated to the data by
the data distinct processing unit and notifies the data
distinct processing unit not notified of the free space
among the plurality of data distinct processing units, of
the new free space.
5. The communication apparatus according to claim 1,
wherein the allocation unit includes a layer processing
unit provided corresponding to the first layer to decide
allocation of the free space to each piece of data based on
a collected data amount after collecting the data amount of
the plurality of pieces of data of the second layer.
6. The communication apparatus according to claim 1,
wherein the acquisition unit acquires the size of the free
space of the plurality of data transmission units
transmitted from mutually different antennas.
7. The communication apparatus according to claim 1,
wherein the acquisition unit acquires the size of the free
space of the plurality of data transmission units
transmitted in different timing.
8. The communication apparatus according to claim 7,
wherein the acquisition unit forecasts channel quality
information in the future from the channel quality information
to date to estimate the size of the free space in the data
transmission units transmitted in the future based on a forecast
result of the channel quality information.
9. A computer readable storage medium having stored therein a
transmission data generation program for causing a computer to
operate as a communication apparatus having a communication
protocol including two layers, the transmission data generation
program causing the computer to execute a process comprising :
acquiring a size of free space provided in each of a
plurality of data transmission units of a first layer and
capable of multiplexing data;
allocating to each of a plurality of pieces of data of a
second layer a contiguous sequence of the free space equal to
the each piece of data in size and provided in one of the data
transmission units of the free space whose size is acquired at
the acquiring ; and
multiplexing the plurality of pieces of data of the second
layer into the plurality of data transmission units of the first
layer according to allocation of the free space by the
allocating.
10. A transmission data generation method causing a computer
to function as a communication apparatus having a communication
protocol including two layers, the transmission data generation
method comprising :
acquiring a size of free space provided in each of a
plurality of data transmission units of a first layer and
capable of multiplexing data;
allocating to each of a plurality of pieces of data of a
second layer a contiguous sequence of the free space equal to
the each piece of data in size and provided in one of the data
transmission units of the free space whose size is acquired at
the acquiring ; and
multiplexing the plurality of pieces of data of the second
layer into the plurality of data transmission units of the first
layer according to allocation of the free space by the
allocating.

To improve transmission efficiency of data and
exercise reliable QoS control. To solve this problem, a
free space allocation unit preferentially sets space that
can be allocated without dividing one RLC-SDU of free space
of an MAC-PDU as allocation space of the RLC-SDU. An RLC-
PDU creation unit creates an RLC-PDU by adding an
appropriate header of an RLC layer to the RLC-SDU output
from an RLC-SDU buffer unit or a retransmission buffer unit.
A radio resource information acquisition unit outputs free
space information to the free space allocation unit of an
RLC processing unit with a highest priority among RLC
processing units not notified of the free space information
of the MAC-PDU. An MAC-PDU creation unit multiplexes the
RLC-PDU according to the allocation space notified from the
free space allocation unit of each RLC processing unit.