WO2013136547A1 - A method of providing control information for user equipment in an lte communication system - Google Patents

A method of providing control information for user equipment in an lte communication system Download PDF

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Publication number
WO2013136547A1
WO2013136547A1 PCT/JP2012/069053 JP2012069053W WO2013136547A1 WO 2013136547 A1 WO2013136547 A1 WO 2013136547A1 JP 2012069053 W JP2012069053 W JP 2012069053W WO 2013136547 A1 WO2013136547 A1 WO 2013136547A1
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WIPO (PCT)
Prior art keywords
pdcch
cce
res
enodeb
mapping
Prior art date
Application number
PCT/JP2012/069053
Other languages
French (fr)
Inventor
Phong Nguyen
Satha Sathananthan
Kevin Lin
Original Assignee
Nec Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2012901017A external-priority patent/AU2012901017A0/en
Application filed by Nec Corporation filed Critical Nec Corporation
Publication of WO2013136547A1 publication Critical patent/WO2013136547A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/003Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048Allocation of pilot signals, i.e. of signals known to the receiver
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/24Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2612Arrangements for wireless medium access control, e.g. by allocating physical layer transmission capacity
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/003Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053Allocation of signaling, i.e. of overhead other than pilot signals
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W72/00Local resource management
    • H04W72/20Control channels or signalling for resource management
    • H04W72/23Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal

Definitions

  • the present invention relates to a method of providing control information for User Equipments (UEs) in data communication with an evolved Node B (eNodeB) over a Long Term Evolution (LTE) wireless communication system, and in particular to using Enhanced Physical Downlink Control Channels (E-PDCCH) for configuring the UEs to communicate data with the eNodeB over the Release 11 and future release of LTE wireless communication system.
  • UEs User Equipments
  • eNodeB evolved Node B
  • LTE Long Term Evolution
  • an eNodeB in the LTE system determines which User Equipment (UE) in the system should be granted uplink resources for data transmission and which UE should be scheduled for data reception in the downlink, and then provides suitable control information for the UEs accordingly.
  • the eNodeB determines an amount of control channel resources of a Physical Downlink Control Channel (PDCCH) that is required and supported for the UEs comprising this control information.
  • PDCCH Physical Downlink Control Channel
  • One aspect of the invention provides a method of providing control information for UEs in data communication with an eNodeB over a Long Term Evolution (LTE) wireless
  • the method comprising: encoding at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UEs to communicate data with the eNodeB over the LTE wireless communication system;
  • E-PDCCH Enhanced-Physical Downlink Control Channel
  • E-PDCCH mapping the at least one E-PDCCH on at least one allocated pair of Physical Resource Blocks (PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs) ;
  • E-CCE Enhanced-Control Channel Element
  • each E-CCE structure has a size of 3, 4, 5, 6, 9, 10, 11, 12, 14 or 16 REGs or equivalently 12, 16, 20, 24, 36, 40, 44, 48, 56 or 64 Resource Elements (REs).
  • REs Resource Elements
  • the E-CCE structure size can vary on a pair of PRBs or group of pairs of PRBs within a sub-frame.
  • the size of the E-CCE structure may be determined at the eNodeB by:
  • the size of the E-CCE structure may be determined at the
  • step (1) using the E-CCE structure size selected in step (1).
  • Another aspect of the invention provides a UE in data communication with an eNodeB over a Long Term Evolution (LTE) wireless communication system, the UE comprising:
  • a controller configured to:
  • E-PDCCH Enhanced-Physical Downlink Control Channel
  • PRBs Physical Resource Blocks
  • E-CCE Enhanced-Control Channel Element
  • REGs Resource Element Groups
  • Yet another aspect of the invention provides an eNodeB in data communication with UEs over a Long Term Evolution (LTE) wireless communication system, the eNodeB
  • LTE Long Term Evolution
  • a controller configured to:
  • E-PDCCH Enhanced-Physical Downlink Control Channel
  • PRBs Enhanced-Control Channel Element
  • E-CCE Enhanced-Control Channel Element
  • REGs Resource Element Groups
  • Fig. 1 is a schematic illustration of a Long Term Evolution (LTE) wireless
  • Fig. 2 is a flow chart illustrating encoding E-PDCCH according to an embodiment of the present invention.
  • Fig. 3 is a graphical representation of an E-CCE of size 36 REs mapping on an allocated PRB pair.
  • Fig. 4 is a graphical representation of an E-CCE of size 12 REs mapping on an allocated PRB pair.
  • Fig. 5 is a graphical representation of an E-CCE aggregation for E-CCE size of 12 REs.
  • Fig. 6 is a graphical representation of an E-CCE aggregation for E-CCE size of 12 REs.
  • Fig. 6 is a graphical representation of an E-CCE of size 20 REs mapping on an allocated PRB pair.
  • Fig. 7 is a graphical representation of an E-CCE aggregation for E-CCE size of 20 REs.
  • Fig. 8 is a graphical representation of an E-CCE aggregation for E-CCE size of 20 REs.
  • Fig. 8 is a graphical representation of different E-PDCCH configurations on the same subframe which requires different E-CCE sizes.
  • Fig. 9 is a flow chart showing steps involved in implementing the calculation of an optimized E-CCE size at an eNodeB.
  • Fig. 10 is a flow chart showing steps involved in implementing the calculation of an optimized E-CCE size at a UE.
  • Fig. 11 is a graphical representation of a first example of spatial multiplexing of different composite control information with the same modulation schemes.
  • Fig. 12 is a graphical representation of a second example of spatial multiplexing of different composite control information with the different modulation schemes.
  • CCE Control-Channel Elements
  • REG resource-element groups
  • the number of CCE(s) - namely one, two, four, or eight - required for a certain PDCCH depends on the payload size of the control information (DCI payload) and the channel-coding rate. This is used to realised link adaptation for the PDCCH. If the channel conditions for the terminal to which the PDCCH is intended are disadvantageous, a larger number of CCEs needs to be used compared to the case of advantageous channel conditions.
  • the number of CCEs used for a PDCCH is also referred to as the aggregation level.
  • the number of CCEs available for PDCCHs depends on the size of the control region, the cell bandwidth, the number of downlink antenna ports, and the amount of resources occupied by PHICH.
  • the sizes of the control region can vary dynamically from sub-frame to sub-frame, whereas other quantities are semi-statically configured.
  • the number of useful RE(s) available for E-PDCCH(s) depends on the size of the control region, the number of allocated PRB pair(s), location of PRB pair(s) (i.e. central 6 or 7 PRBs or other), sub-frame number (i.e. sub-frame #0, 5 or special sub-frame in case of type 2 sub-frame or other sub-frames), the number of CRS configuration, UE specific RS configuration, CSI-RS configuration, and sub-frame's type (i.e. normal CP or extended CP).
  • control region can vary dynamically from sub-frame to sub-frame, whereas other quantities are semi-statically configured but can also affect the number useful RE(s) available for E-PDCCH(s) mapping sub-frame by sub-frame due to the CSI-RS appearing periodically, REs reserved for PBCH, PSS, SSS, PRS and/or special sub-frame in case of type-2 frame structure. This leads to the ineffective usage of the available channel resources if the same CCE size (i.e. 9 REGs) as the legacy PDCCH is used.
  • the used RE(s) are not actually located at the end of sub-frame but are distributed around the allocated PBRs pair after the interleaving function 380 of E-PDCCH coding structure shown in Fig. 2, in the case of:
  • Control region size is 2 OFDM symbols, 3. 1 Pair of PRBs is allocate for a E-PDCCH within the central 72 sub carrier
  • Sub-frame number is not 0 or 5 or special sub-frame in case of type-2 frame structure.
  • the maximum aggregation level of 8 with possible aggregation levels of 4 and 8 in case of E-PDCCH(s) is QPSK modulated with the assumption that the current ambiguous sizes of information bit of 12, 14, or 16 is used as being illustrated in the lower parts of Fig. 5. That provides better link adaptation in term of different aggregation level.
  • multiple E-PDCCH(s) with the same modulation level can be multiplexed and utilised all available REs with possible aggregation levels of ⁇ 2, 4, 8 ⁇ . This illustrated in Fig. 5 for 16-QAM and 64-QAM modulated E-PDCCH(s).
  • the maximum aggregation level of 4 with no other possible aggregation levels in case of E-PDCCH(s) is QPSK modulated as being illustrated in the upper part of Fig. 7.
  • QPSK modulated As being illustrated in the upper part of Fig. 7.
  • E-PDCCH(s) with the same modulation level can be multiplexed and utilised all available REs with possible aggregation levels of ⁇ 1, 2, 4 ⁇ . This is illustrated in the lower parts of Fig. 7 for 16-QAM and 64-QAM modulated E-PDCCH(s).
  • the present invention proposes a set of different E-CCE sizes to be used for E-PDCCH, as well as a method for calculating and selecting of appropriate E-CCE sizes on a sub-frame basis for implementation at the eNodeB and UEs so that there is no need to use signalling to inform a UE of the configured E-CCE size used at its eNodeB.
  • E-PDCCH is but not limited to ⁇ 3, 4, 5, 6, 9, 10, 11, 12, 14, 16 ⁇ REGs or being equivalent to ⁇ 12, 16, 20, 24, 36, 40, 44, 48, 56, 64 ⁇ REs.
  • FIG. 1 An LTE wireless communication system 100 supporting E-PDCCH with variable E-CCE size is illustrated in Fig. 1.
  • the wireless system 100 comprises an eNodeB 110 for encoding control information and transmission of E-PDCCH(s) to an intended UE 150 via wireless channel using
  • E-CCE size calculation function 1 1 1 to derive optimum E-CCE size for link adaptation
  • E-PDCCH(s) physical channel processing function 1 15 to perform layer mapping, pre-coding and E-PDCCH(s) RE mapping on allocated PRB pairs for transmitting E-PDCCHs. Furthermore, the eNodeB can map E-PDCCH(s) with different configurations targeting different group of UEs or group of E-PDCCHs to maximise channel condition, link adaptation, and beamforming as well as performance target as being illustrated in Fig. 8.
  • E-PDCCH channel coding and physical channel coding (300) is further illustrated in Fig. 2.
  • the exemplary eNodeB implemented E-PDCCH(s) physical channel processing function 115 has spatial multiplexing of composite control information stream with same or different modulation schemes for multi-layers transmission and precoding as being illustrated in Figs. 11 and 12 respectively.
  • the wireless system 100 further comprises a UE 150 for performing the reception, detection and decoding of its indented E-PDCCH(s) using E-PDCCH(s) reception function 153, E-CCE size calculation function 151, and E-PDCCH(s) blind decoding function 152.
  • the eNodeB implemented E-CCE size calculation function is further described in the following steps with the summarised procedure specified in Fig. 9.
  • UE(s) belonging to an eNodeB are geometrically distributed and therefore different configurations for a UE or group of UE(s) can improve the E-PDCCH(s) demodulation performance.
  • This also requires different E-CCE sizes to be used for each UE or group of UE(s) which shares the same allocated PRB pairs for E-PDCCH(s) RE(s) mapping and/or beam forming configuration.
  • the eNodeB calculates E-CCE sizes for all possible size of control region and sub-frame with and without CSI-RS using the following steps:
  • the eNodeB uses the calculated E-CCE size corresponding to the dynamically configured control region size with or without CSI-RS for the E-PDCCH encoding, E-CCEs aggregation and E-PDCCH(s) multiplexing. These eNodeB calculated E-CCE size(s) will be valid until the set of semi-static parameters being reconfigured and activated or number of allocated PRB-pairs has been changed and become effective.
  • the UE(s) implements the procedure for calculating E-CCE sizes described in the following steps with the summarised procedure specified in Fig. 10.
  • an eNodeB can configure a UE to monitor different set of allocated PRB pairs for different E-PDCCH(s) configurations as being illustrated in Fig. 8. This also requires different E-CCE sizes to be used for each E-PDCCH
  • E-PDCCH configurations that a UE is configured to monitor For each E-PDCCH configurations that a UE is configured to monitor the UE calculates E-CCE sizes for all possible sizes of control region and sub-frame with and without CSI-RS, using the following steps:
  • the UE will use the calculated E-CCE size corresponding to the dynamically detected control region size and with or without CSI-RS for the E-PDCCH(s) reception and E-PDCCH(s) blind decoding for its intended control information. These UE's calculated E-CCE size(s) will be valid until the set of semi-static parameters being reconfigured and activated or number of allocated PRB -pairs has been changed and become effective.
  • E-PDCCH E-CCE sizes can be selected and configured by eNodeB to effectively utilise the Resource Element(s) ( REs ) available for mapping the E-PDCCH(s) in a pair of PRB(s) or multiple pairs of PRB(s).
  • REs Resource Element
  • Procedures are implemented by the eNodeB for calculating optimised E-CCE sizes and applying the calculated E-CCE on subframe basis without notifying UE.
  • Procedures are implemented by the UE for calculating optimised E-CCE sizes used by eNodeB and applying the correct E-CCE used by eNodeB on sub-frame by sub-frame basis and E-PDCCH configuration by E-PDCCH configuration basis without signalling.
  • E-PDCCH(s) are mapped with different configurations on the same channel BW to obtain optimum link adaptation and channel conditions and maintain optimised E-PDCCHs channel allocation by using different E-CCE sizes on different E-PDCCH configuration.
  • the present invention can be applied to a method of providing control information for User Equipment (UEs) in data communication with an eNodeB over a Long Term Evolution (LTE) wireless communication system.
  • UEs User Equipment
  • LTE Long Term Evolution

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Abstract

There is provided a method of providing control information for UEs (150) in data communication with an eNodeB (110) over a LTE wireless communication system (100). This method includes: encoding at least one E-PDCCH that includes control information for configuring the UEs (150) to communicate data with the eNodeB (110) over the LTE wireless communication system (100); mapping the at least one E-PDCCH on at least one allocated pair of PRBs according to an E-CCE structure including a variable number of REGs; varying the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and communicating the at least one E-PDCCH mapped onto the at least one allocated pair of PRBs to the UEs (150) so that the UEs (150) can be configured to communicate the data over the LTE wireless communication system (100) based on the control information.

Description

DESCRIPTION
Title of Invention
A METHOD OF PROVIDING CONTROL INFORMATION FOR USER EQUIPMENT IN AN LTE COMMUNICATION SYSTEM
Technical Field
[0001]
The present invention relates to a method of providing control information for User Equipments (UEs) in data communication with an evolved Node B (eNodeB) over a Long Term Evolution (LTE) wireless communication system, and in particular to using Enhanced Physical Downlink Control Channels (E-PDCCH) for configuring the UEs to communicate data with the eNodeB over the Release 11 and future release of LTE wireless communication system.
Background Art
[0002]
In existing Long Term Evolution (LTE) wireless communication systems, such as LTE Release 8, 9 and 10, an eNodeB in the LTE system determines which User Equipment (UE) in the system should be granted uplink resources for data transmission and which UE should be scheduled for data reception in the downlink, and then provides suitable control information for the UEs accordingly. In one example, the eNodeB determines an amount of control channel resources of a Physical Downlink Control Channel (PDCCH) that is required and supported for the UEs comprising this control information.
Summary of Invention
Technical Problem
[0003]
There current exists a need to optimise the use of control channel resources to improve system capabilities of LTE wireless communication systems.
Solution to Problem
[0004]
One aspect of the invention provides a method of providing control information for UEs in data communication with an eNodeB over a Long Term Evolution (LTE) wireless
communication system, the method comprising: encoding at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UEs to communicate data with the eNodeB over the LTE wireless communication system;
mapping the at least one E-PDCCH on at least one allocated pair of Physical Resource Blocks (PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs) ;
varying the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and
communicating the at least one E-PDCCH mapped onto the at least one allocated pair of PRBs to the UEs so that the UEs can be configured to communicate said data over the LTE wireless communication system based on the control information.
[0005]
In one or more embodiments, each E-CCE structure has a size of 3, 4, 5, 6, 9, 10, 11, 12, 14 or 16 REGs or equivalently 12, 16, 20, 24, 36, 40, 44, 48, 56 or 64 Resource Elements (REs).
[0006]
In one or more embodiments, the E-CCE structure size can vary on a pair of PRBs or group of pairs of PRBs within a sub-frame.
[0007]
When implemented at an eNodeB, the size of the E-CCE structure may be determined at the eNodeB by:
(1) calculating the number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping on a PRB pair or multiple PRB pairs intended for E-PDCCH(s);
(2) for each E-CCE structure size, calculating the number of remainder REs of the calculated number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the E-CCE structure size in numbers of REs;
(3) selecting the E-CCE structure size that gives the smallest number of remainder REs in step (2); and
(4) if there are more than 1 E-CCE structure sizes giving the smallest number of remainder REs, then:
a. for each E-CCE structure size giving the smallest number of remainder REs, determining the maximum possible aggregation level from nominated aggregation levels of 1, 2, 4 and 8,
b. for each E-CCE structure size, calculating the remainder of the calculated number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the maximum possible aggregation level in step (4) a. in number of REs,
c. selecting the E-CCE structure size with the smallest remainder,
(5) or if not, then using the E-CCE structure size selected in step (3).
[0008]
When implemented at a UE, the size of the E-CCE structure may be determined at the
UE by:
(1) calculating the number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in allocated PRB pair or multiple PRB pairs;
(2) for each E-CCE structure size, calculating the number of remainder REs of the calculated number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the E-CCE structure size in numbers of REs;
(3) selecting the E-CCE structure size that gives the smallest number of remainder REs in step (2); and
(4) if there are more than 1 E-CCE structure sizes giving the smallest number of remainder REs, then:
a. for each E-CCE structure size giving the smallest number of remainder REs, determining the maximum possible aggregation level from nominated aggregation levels of 1 , 2, 4 and 8,
b. for each E-CCE structure size, calculating the remainder of the calculated number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the maximum possible aggregation level in step (4) a. in number of REs,
c. selecting the E-CCE structure size with the smallest remainder,
(5) or if not, then using the E-CCE structure size selected in step (1).
[0009]
Another aspect of the invention provides a UE in data communication with an eNodeB over a Long Term Evolution (LTE) wireless communication system, the UE comprising:
a controller configured to:
receive at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UE to communicate data with the eNodeB over the LTE wireless communication system, the at least one E-PDCCH being mapped on at least one allocated pair of Physical Resource Blocks (PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs);
vary the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and
configure the UE for communicating data with the eNodeB over the LTE wireless communication system based on the control information.
[0010]
Yet another aspect of the invention provides an eNodeB in data communication with UEs over a Long Term Evolution (LTE) wireless communication system, the eNodeB
comprising:
a controller configured to:
transmit at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UEs to communicate data with the eNodeB over the LTE wireless communication system, the at least one E-PDCCH being mapped on at least one allocated pair of Physical Resource Blocks
(PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs);
vary the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and
configure the eNodeB for communicating data with the UEs over the LTE wireless communication system based on the control information.
Advantageous Effects of Invention
[0011]
According to the present invention, it is possible to at least optimise the use of control channel resources to improve system capabilities of LTE wireless communication systems.
Brief Description of Drawings
[0012]
[Fig. 1]
Fig. 1 is a schematic illustration of a Long Term Evolution (LTE) wireless
communication system according to an embodiment of the present invention.
[Fig- 2]
Fig. 2 is a flow chart illustrating encoding E-PDCCH according to an embodiment of the present invention.
[Fig. 3]
Fig. 3 is a graphical representation of an E-CCE of size 36 REs mapping on an allocated PRB pair.
[Fig. 4]
Fig. 4 is a graphical representation of an E-CCE of size 12 REs mapping on an allocated PRB pair.
[Fig- 5]
Fig. 5 is a graphical representation of an E-CCE aggregation for E-CCE size of 12 REs. [Fig. 6]
Fig. 6 is a graphical representation of an E-CCE of size 20 REs mapping on an allocated PRB pair.
[Fig- 7]
Fig. 7 is a graphical representation of an E-CCE aggregation for E-CCE size of 20 REs. [Fig. 8]
Fig. 8 is a graphical representation of different E-PDCCH configurations on the same subframe which requires different E-CCE sizes.
[Fig. 9]
Fig. 9 is a flow chart showing steps involved in implementing the calculation of an optimized E-CCE size at an eNodeB.
[Fig. 10]
Fig. 10 is a flow chart showing steps involved in implementing the calculation of an optimized E-CCE size at a UE.
[Fig. 11]
Fig. 11 is a graphical representation of a first example of spatial multiplexing of different composite control information with the same modulation schemes.
[Fig. 12]
Fig. 12 is a graphical representation of a second example of spatial multiplexing of different composite control information with the different modulation schemes.
Description of Embodiments
[0013]
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. [0014]
In the current legacy PDCCH design, the mapping of PDCCHs to resource elements is subject to a structure of so called Control-Channel Elements (CCE ), which is a set of 36 useful resources elements that is in turn grouped into 9 resource-element groups (REG) with each REG consisting of 4 RE(s). The number of CCE(s) - namely one, two, four, or eight - required for a certain PDCCH depends on the payload size of the control information (DCI payload) and the channel-coding rate. This is used to realised link adaptation for the PDCCH. If the channel conditions for the terminal to which the PDCCH is intended are disadvantageous, a larger number of CCEs needs to be used compared to the case of advantageous channel conditions. The number of CCEs used for a PDCCH is also referred to as the aggregation level.
[0015]
For the legacy PDCCH, the number of CCEs available for PDCCHs depends on the size of the control region, the cell bandwidth, the number of downlink antenna ports, and the amount of resources occupied by PHICH. The sizes of the control region can vary dynamically from sub-frame to sub-frame, whereas other quantities are semi-statically configured.
[0016]
According to the working assumption and agreement achieved for the E-PDCCH (Enhanced - PDCCH), the number of useful RE(s) available for E-PDCCH(s) depends on the size of the control region, the number of allocated PRB pair(s), location of PRB pair(s) (i.e. central 6 or 7 PRBs or other), sub-frame number (i.e. sub-frame #0, 5 or special sub-frame in case of type 2 sub-frame or other sub-frames), the number of CRS configuration, UE specific RS configuration, CSI-RS configuration, and sub-frame's type (i.e. normal CP or extended CP). The size of control region can vary dynamically from sub-frame to sub-frame, whereas other quantities are semi-statically configured but can also affect the number useful RE(s) available for E-PDCCH(s) mapping sub-frame by sub-frame due to the CSI-RS appearing periodically, REs reserved for PBCH, PSS, SSS, PRS and/or special sub-frame in case of type-2 frame structure. This leads to the ineffective usage of the available channel resources if the same CCE size (i.e. 9 REGs) as the legacy PDCCH is used.
[0017]
In the simplified example shown in Fig. 3, the used RE(s) are not actually located at the end of sub-frame but are distributed around the allocated PBRs pair after the interleaving function 380 of E-PDCCH coding structure shown in Fig. 2, in the case of:
1. Normal CP sub-frame
2. Control region size is 2 OFDM symbols, 3. 1 Pair of PRBs is allocate for a E-PDCCH within the central 72 sub carrier
4. Sub-frame number is not 0 or 5 or special sub-frame in case of type-2 frame structure.
5. 2 CRS antenna ports,
6. 2 DMRS antenna ports,
7. 2 CSI-RS antenna ports,
8. On sub-frame without CSI-RS.
[0018]
If the same design as the legacy PDCCH is applied with CCE size of 9 REG(s) (or 36 REs ) and aggregation level of 2, there are 12 REGs (or 48 REs ) left unused which can possibly be used for E-PDCCH REs additional mapping to increase coding gain hence to improve the E-PDCCH demodulation performance. These unused RE(s) occupy 40% of overall channel capacity available for E-PDCCH mapping. In this case, with the assumption that the current ambiguous sizes of information bit of 12, 14, or 16 is used, the maximum aggregation level is 2 and aggregation level of 1 is not applicable for QPSK modulated E-PDCCH unless coding rate higher than 1/3 is used. This shall limit the link adaptation on the transmitted E-PDCCH that is only 1 coding rate can be used to enable to aggregation level of 1.
[0019]
In reference to Fig. 4, and once again noting that this figure is simplified only for illustration purpose as the used RE(s) are not actually located in logical order but being distributed around the allocated PRB pair after the interleaving function 380 of Fig. 2, instead of using CCE size of 9 REG(s) (or 36 RE ), the E-CCE size of 3 REG(s) (or 12 REs ) is utilised. There will be 10 CCEs can be fitted into the allocated pair of PRB. If aggregation level of 8 is used. There are 6 REGs (i.e. 24 REs ) left unused. That is 20% overall channel capacity available for E-PDCCH mapping. Furthermore, the maximum aggregation level of 8 with possible aggregation levels of 4 and 8 in case of E-PDCCH(s) is QPSK modulated with the assumption that the current ambiguous sizes of information bit of 12, 14, or 16 is used as being illustrated in the lower parts of Fig. 5. That provides better link adaptation in term of different aggregation level. When considering higher modulation schemes such as 16-QAM or 64-Q AM, multiple E-PDCCH(s) with the same modulation level can be multiplexed and utilised all available REs with possible aggregation levels of {2, 4, 8}. This illustrated in Fig. 5 for 16-QAM and 64-QAM modulated E-PDCCH(s).
[0020]
In reference to Fig. 6, and once again noting that this figure is simplified only for illustration purpose as the used RE(s) are not actually located logical order but being distributed around the allocated PRB pair after the interleaving function 380 of Fig. 2, instead of using CCE size of 9 REG(s) (i.e. 36 REs ), the E-CCE size of 5 REG(s) (i.e. 20 REs ) is utilised. 6 CCEs can be fitted into the allocated pair of PRB if an aggregation level of 4 is used. There are 10 REGs (or 40 REs ) left unused. That is 33% overall channel capacity available for E-PDCCH mapping. Furthermore, the maximum aggregation level of 4 with no other possible aggregation levels in case of E-PDCCH(s) is QPSK modulated as being illustrated in the upper part of Fig. 7. When considering higher modulation schemes such as 16-QAM or 64-QAM, multiple
E-PDCCH(s) with the same modulation level can be multiplexed and utilised all available REs with possible aggregation levels of { 1, 2, 4} . This is illustrated in the lower parts of Fig. 7 for 16-QAM and 64-QAM modulated E-PDCCH(s).
[0021]
The above examples demonstrate the need for different CCE size design for E-PDCCH in order to utilise the channel capacity allocated to E-PDCCH efficiently as well as allow link adaptation being realised effectively.
[0022]
According to one or more embodiments, the present invention proposes a set of different E-CCE sizes to be used for E-PDCCH, as well as a method for calculating and selecting of appropriate E-CCE sizes on a sub-frame basis for implementation at the eNodeB and UEs so that there is no need to use signalling to inform a UE of the configured E-CCE size used at its eNodeB.
[0023]
According to one or more embodiments, the set of E-CCE sizes nominated for
E-PDCCH is but not limited to {3, 4, 5, 6, 9, 10, 11, 12, 14, 16 } REGs or being equivalent to { 12, 16, 20, 24, 36, 40, 44, 48, 56, 64} REs.
[0024]
An LTE wireless communication system 100 supporting E-PDCCH with variable E-CCE size is illustrated in Fig. 1.
[0025]
The wireless system 100 comprises an eNodeB 110 for encoding control information and transmission of E-PDCCH(s) to an intended UE 150 via wireless channel using
a. implemented E-PDCCH encoding function 1 12 to encode the transmitted control information,
b. E-CCE size calculation function 1 1 1 to derive optimum E-CCE size for link adaptation, c. implemented E-CCE(s) aggregation function 1 13 and E-PDCCHs multiplexing function 1 14 to form composite control information, and
d. Implemented E-PDCCH(s) physical channel processing function 1 15 to perform layer mapping, pre-coding and E-PDCCH(s) RE mapping on allocated PRB pairs for transmitting E-PDCCHs. Furthermore, the eNodeB can map E-PDCCH(s) with different configurations targeting different group of UEs or group of E-PDCCHs to maximise channel condition, link adaptation, and beamforming as well as performance target as being illustrated in Fig. 8.
[0026]
The detailed E-PDCCH channel coding and physical channel coding (300) is further illustrated in Fig. 2.
[0027]
Additionally, the exemplary eNodeB implemented E-PDCCH(s) physical channel processing function 115 has spatial multiplexing of composite control information stream with same or different modulation schemes for multi-layers transmission and precoding as being illustrated in Figs. 11 and 12 respectively.
[0028]
The wireless system 100 further comprises a UE 150 for performing the reception, detection and decoding of its indented E-PDCCH(s) using E-PDCCH(s) reception function 153, E-CCE size calculation function 151, and E-PDCCH(s) blind decoding function 152.
[0029]
The eNodeB implemented E-CCE size calculation function is further described in the following steps with the summarised procedure specified in Fig. 9.
[0030]
In a wireless system, UE(s) belonging to an eNodeB are geometrically distributed and therefore different configurations for a UE or group of UE(s) can improve the E-PDCCH(s) demodulation performance. This also requires different E-CCE sizes to be used for each UE or group of UE(s) which shares the same allocated PRB pairs for E-PDCCH(s) RE(s) mapping and/or beam forming configuration. For each group of UEs who share the same allocated PRB pairs for E-PDCCHs RE mapping , have the same DMRS configuration, and have same beam forming configuration setting, with each semi-static configuration the eNodeB calculates E-CCE sizes for all possible size of control region and sub-frame with and without CSI-RS using the following steps:
1. Calculate number of RE(s) available for E-PDCCH(s) mapping, 2. For each E-CCE size, calculate the remainder RE(s) of the Calculated number of RE(s) available for E-PDCCH(s) mapping in (1) divided by E-CCE size in number of PvE(s),
3. Select E-CCE size(s) that give the smallest remainder in (2),
4. If there are more than 1 E-CCE sizes giving the same smallest remainder, then
a. For each E-CCE size giving the same smallest remainder, Determine the maximum possible aggregation level, and the nominate aggregation level is { 1, 2, 4, 8},
b. For each E-CCE size calculate the remainder of the Calculated number of RE(s) available for E-PDCCH(s) mapping in (1) divided by maximum possible aggregation level in (a) in number of RE(s),
c. Select E-CCE size with the smallest remainder.
5. Else, use the E-CCE size selected in (3)
[0031]
For every sub-frame the eNodeB uses the calculated E-CCE size corresponding to the dynamically configured control region size with or without CSI-RS for the E-PDCCH encoding, E-CCEs aggregation and E-PDCCH(s) multiplexing. These eNodeB calculated E-CCE size(s) will be valid until the set of semi-static parameters being reconfigured and activated or number of allocated PRB-pairs has been changed and become effective.
[0032]
To enable UE(s) to apply the same E-CCE sizes that have been calculated and used by eNodeB without signalling, the UE(s) implements the procedure for calculating E-CCE sizes described in the following steps with the summarised procedure specified in Fig. 10.
[0033]
In a wireless system such as system 100, an eNodeB can configure a UE to monitor different set of allocated PRB pairs for different E-PDCCH(s) configurations as being illustrated in Fig. 8. This also requires different E-CCE sizes to be used for each E-PDCCH
configurations that a UE is configured to monitor. For each E-PDCCH configurations that a UE is configured to monitor the UE calculates E-CCE sizes for all possible sizes of control region and sub-frame with and without CSI-RS, using the following steps:
1. Calculate number of RE(s) available for E-PDCCH(s) mapping,
2. For each E-CCE size, calculate the remainder RE(s) of the Calculated number of RE(s) available for E-PDCCH(s) mapping in (1) divided by E-CCE size in number of RE(s),
3. Select E-CCE size(s) that give the smallest remainder in (2),
4. If there are more than 1 E-CCE sizes giving the same smallest remainder, then a. For each E-CCE size giving the same smallest remainder, Determine the maximum possible aggregation level, and the nominate aggregation level is { 1, 2, 4, 8},
b. For each E-CCE size calculate the remainder of the Calculated number of RE(s) available for E-PDCCH(s) mapping in (1) divided by maximum possible aggregation level in (a) in number of RE(s),
c. Select E-CCE size with the smallest remainder.
5. Else, use the E-CCE size selected in (3)
[0034]
For every sub-frame, the UE will use the calculated E-CCE size corresponding to the dynamically detected control region size and with or without CSI-RS for the E-PDCCH(s) reception and E-PDCCH(s) blind decoding for its intended control information. These UE's calculated E-CCE size(s) will be valid until the set of semi-static parameters being reconfigured and activated or number of allocated PRB -pairs has been changed and become effective.
[0035]
From the foregoing, it will be appreciated that the various described embodiments of the invention provide the following non-exhaustive list of advantages:
1. Various E-PDCCH E-CCE sizes can be selected and configured by eNodeB to effectively utilise the Resource Element(s) ( REs ) available for mapping the E-PDCCH(s) in a pair of PRB(s) or multiple pairs of PRB(s).
2. Procedures are implemented by the eNodeB for calculating optimised E-CCE sizes and applying the calculated E-CCE on subframe basis without notifying UE.
3. Procedures are implemented by the UE for calculating optimised E-CCE sizes used by eNodeB and applying the correct E-CCE used by eNodeB on sub-frame by sub-frame basis and E-PDCCH configuration by E-PDCCH configuration basis without signalling.
4. E-PDCCH(s) are mapped with different configurations on the same channel BW to obtain optimum link adaptation and channel conditions and maintain optimised E-PDCCHs channel allocation by using different E-CCE sizes on different E-PDCCH configuration.
5. Composite control information streams are multiplexed with different E-CCE aggregation and modulation schemes
[0036]
It is to be understood that various alterations, additions and/or modifications may be made to the parts previously described without departing from the ambit of the present invention, and that, in the light of the above teachings, the present invention may be implemented in software, firmware and/or hardware in a variety of manners as would be understood by the skilled person.
[0037]
The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.
[0038]
Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.
[0039]
This application is based upon and claims the benefit of priority from Australian
Provisional Patent Application No.2012901017, filed on March 14, 2012, the disclosure of which is incorporated herein in its entirety by reference.
Industrial Applicability
[0040]
The present invention can be applied to a method of providing control information for User Equipment (UEs) in data communication with an eNodeB over a Long Term Evolution (LTE) wireless communication system. Reference Signs List
[0041]
100 LTE WIRELESS COMMUNICATION SYSTEM
110 eNodeB
111 E-CCE SIZE CALCULATION FUNCTION
112 E-PDCCH ENCODING FUNCTION
113 E-CCE(s) AGGREGATION FUNCTION
114 E-PDCCHs MULTIPLEXING FUNCTION
115 E-PDCCH(s) PHYSICAL CHANNEL PROCESSING FUNCTION
150 USER EQUIPMENT (UE) E-CCE SIZE CALCULATION FUNCTION E-PDCCH(s) BLIND DECODING FUNCTION E-PDCCH(s) RECEPTION FUNCTION

Claims

[Claim 1]
A method of providing control information for UEs in data communication with an eNodeB over a Long Term Evolution (LTE) wireless communication system, the method comprising:
encoding at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UEs to communicate data with the eNodeB over the LTE wireless communication system;
mapping the at least one E-PDCCH on at least one allocated pair of Physical Resource Blocks (PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs) ;
varying the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and
communicating the at least one E-PDCCH mapped onto the at least one allocated pair of PRBs to the UEs so that the UEs can be configured to communicate said data over the LTE wireless communication system based on the control information.
[Claim 2]
The method according to claim 1, wherein each E-CCE structure has a size of 3, 4, 5, 6,9, 10, 11 , 12, 14 or 16 REGs or equivalently 12, 16, 20, 24, 36, 40, 44, 48, 56 or 64 Resource Elements (REs) respectively..
[Claim 3]
The method according to either one of claims 1 or 2 when implemented at an eNodeB, wherein the size of the E-CCE structure is determined at the eNodeB by:
(1) calculating the number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping on a PRB pair or multiple PRB pairs intended for E-PDCCH(s);
(2) for each E-CCE structure size, calculating the number of remainder REs of the calculated number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the E-CCE structure size in numbers of REs;
(3) selecting the E-CCE structure size that gives the smallest number of remainder REs in step (2); and
(4) if there are more than 1 E-CCE structure sizes giving the smallest number of remainder REs, then: a. for each E-CCE structure size giving the smallest number of remainder REs, determining the maximum possible aggregation level from nominated aggregation levels of 1, 2, 4 and 8,
b. for each E-CCE structure size, calculating the remainder of the calculated
number of REs available for E-PDCCH PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the maximum possible aggregation level in step (4) a. in number of REs,
c. selecting the E-CCE structure size with the smallest remainder,
(5) or if not, then using the E-CCE structure size selected in step (3).
[Claim 4]
The method according to either one of claims 1 or 2 when implemented at a UE, wherein the size of the E-CCE structure is determined at the UE by:
(1) calculating the number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in allocated PRB pair or multiple PRB pairs;
(2) for each E-CCE structure size, calculating the number of remainder REs of the calculated number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the E-CCE structure size in numbers of REs;
(3) selecting the E-CCE structure size that gives the smallest number of remainder REs in step (2); and
(4) if there are more than 1 E-CCE structure sizes giving the smallest number of remainder REs, then:
a. for each E-CCE structure size giving the smallest number of remainder REs, determining the maximum possible aggregation level from nominated aggregation levels of 1, 2, 4 and 8,
b. for each E-CCE structure size, calculating the remainder of the calculated
number of REs available for E-PDCCH or multiplexed E-PDCCHs mapping in the step (1), divided by the maximum possible aggregation level in step (4) a. in number of REs,
c. selecting the E-CCE structure size with the smallest remainder,
(5) or if not, then using the E-CCE structure size selected in step (1).
[Claim 5] A UE in data communication with an eNodeB over a Long Term Evolution (LTE) wireless communication system, the UE comprising:
a controller configured to:
transmit at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UE to communicate data with the eNodeB over the LTE wireless communication system, the at least one E-PDCCH being mapped on at least one allocated pair of Physical Resource Blocks (PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs);
vary the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and
configure the UE for communicating data with the eNodeB over the LTE wireless communication system based on the control information.
[Claim 6]
An eNodeB in data communication with UEs over a Long Term Evolution (LTE) wireless communication system, the eNodeB comprising:
a controller configured to:
receive at least one Enhanced-Physical Downlink Control Channel (E-PDCCH) comprising control information for configuring the UEs to communicate data with the eNodeB over the LTE wireless communication system, the at least one E-PDCCH being mapped on at least one allocated pair of Physical Resource Blocks (PRBs) according to an Enhanced-Control Channel Element (E-CCE) structure including a variable number of Resource Element Groups (REGs);
vary the number of REGs in an E-CCE structure to optimise the channel capacity utilisation for the E-PDCCH mapping; and
configure the eNodeB for communicating data with the UEs over the LTE wireless communication system based on the control information.
PCT/JP2012/069053 2012-03-14 2012-07-19 A method of providing control information for user equipment in an lte communication system WO2013136547A1 (en)

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