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WO2008105718A1 - Allocation de transmission de liaison montante et de liaison descendante dans tdd dans un domaine orthogonal. - Google Patents

Allocation de transmission de liaison montante et de liaison descendante dans tdd dans un domaine orthogonal. Download PDF

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Publication number
WO2008105718A1
WO2008105718A1 PCT/SE2008/050128 SE2008050128W WO2008105718A1 WO 2008105718 A1 WO2008105718 A1 WO 2008105718A1 SE 2008050128 W SE2008050128 W SE 2008050128W WO 2008105718 A1 WO2008105718 A1 WO 2008105718A1
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WO
WIPO (PCT)
Prior art keywords
communications
domain
node
transmissions
duplex
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/SE2008/050128
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English (en)
Inventor
Erik Westerberg
Krister Sundberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefonaktiebolaget LM Ericsson AB
Original Assignee
Telefonaktiebolaget LM Ericsson AB
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
Application filed by Telefonaktiebolaget LM Ericsson AB filed Critical Telefonaktiebolaget LM Ericsson AB
Publication of WO2008105718A1 publication Critical patent/WO2008105718A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/14—Spectrum sharing arrangements between different networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0037—Inter-user or inter-terminal allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1469—Two-way operation using the same type of signal, i.e. duplex using time-sharing
    • H04L5/1484—Two-way operation using the same type of signal, i.e. duplex using time-sharing operating bytewise
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A) or DMT

Definitions

  • the present invention relates to communication systems comprising time division duplex, TDD, technologies, and more especially it relates to allocation of uplink and downlink communications in such communication systems. Particularly, it relates to allocation of communications in such systems in another domain, such as frequency domain.
  • Time division duplex systems are receiving an increasing interest due to its relieved requirement on paired spectrum, required for frequency division duplex, FDD, systems.
  • FDD frequency division duplex
  • TDD allows use of a single frequency band for both uplink and downlink communications.
  • the single band requirement simplifies frequency licensing to various opera ⁇ tors .
  • Orthogonal Frequency Division Multiplex OFDM
  • radio interface systems e.g. WiMAX (Worldwide Interoperability for Microwave Access) uses a plurality of frequencies separated in frequency domain such that they do not correlate. The frequencies are said to be orthogonal .
  • WiMAX forum 'IEEE 802.16a Standard and WiMAX Igniting Broadband Wireless Access, White Paper, ' 2003, provides an overview of the IEEE 802.16a Standard and includes a discussion on the MAC (Media Access Control) layer and physical layer in WiMAX.
  • MAC Media Access Control
  • Gabor Fodor 'Performance Analysis of a Reuse Partitioning Technique for OFDM Based Evolved UTRA, ' Fourteenth IEEE International Workshop on Quality of Service (IWQoS 2006), June 19-21, 2006, USA, proposes and analyzes a simple reuse partitioning technique (assuming coordinated sub-carrier allocation in the cells) claimed to be capable of minimizing inter-cell interference.
  • System performance of OFDMA based systems in terms of sub-carrier collisions, session blocking probabilities and signal-to-noise-and-interference ratio is presented with numerical results.
  • 3GPP The 3 rd Generation Partnership Project, 3GPP, provides e.g. technical specifications for WCDMA (Wideband Code Division Multiple Access) systems, forming a substantial part of universal mobile telecommunications systems, UMTS, also specified by 3GPP.
  • WCDMA Wideband Code Division Multiple Access
  • UMTS universal mobile telecommunications systems
  • An extension of today's systems includ- ing among other things new modulation is included in their LTE (Long Term Evolution) and SAE (System Architecture Evolution) not affecting GPRS.
  • LTE Long Term Evolution
  • SAE System Architecture Evolution
  • the described technologies include or- thogonal frequency-division multiplexing, OFDM, single- carrier FDMA (frequency division multiple access) with dynamic bandwidth, SC-FDMA, multi-antenna solutions, evolved quality of service and link-layer concepts, and evolved system architecture.
  • AML-OFDM Adaptive Multilayer OFDM
  • AML-OFDM sub-carriers By varying the number of AML-OFDM sub-carriers, different allocations of spectrum ranging from 1.25 MHz to 20 MHz are supported.
  • OFDM facilitates smooth migration, e.g., of 2G spectrum.
  • a GSM operator may migrate on a carrier-by- carrier (for GSM 200 kHz wide) basis using only a fraction of available OFDM sub-carriers.
  • AML-OFDM support of time-division and frequency-division duplex operation Single-carrier Frequency Division Multiple Access, SC-FDMA, with dynamic bandwidth is preferred for up ⁇ link transmissions due to its power efficiency.
  • SC-FDMA Single-carrier Frequency Division Multiple Access
  • Each base station of a cellular radio communication system assigns terminals a unique frequency for transmitting user data and ensuring intra-cell orthogonality, thus avoiding intra-cell interference. Most of the time, time-domain scheduling is used to separate users .
  • Frequency-domain scheduling is used for terminals with limited power or little data to transmit. With limited transmission power mobile terminals cannot transmit a pilot signal covering an entire frequency band continuously. Because of limited knowledge of uplink channel conditions, frequency-domain adaptation is usually not used in the uplink. Slow power control is used to compensate for path loss and shadow fading. Thanks to the orthogonality of uplink transmissions, there is no need for fast power control to handle any near-far problem. Interference due to multipath propagation is handled at the base station, aided by insertion of a cyclic prefix in the transmitted signal. The transmission parameters, coding and modulation are similar to those of the downlink transmissions.
  • Figure 1 illustrates schematically a radio communications system, but is essentially applicable to any wireless communications system.
  • GSN+ An enhanced Gateway GPRS (Global Packet Radio Services) Support Node, GSN+, is a gateway anchor node in the home network.
  • Anchor 1 «Central Anchor 2» control base stations, or nodes B, «Node B ⁇ », «Node B 2 » «Node B 3 » «Node B 4 » interconnecting wireless user equipment «UE].
  • U.S. Patent No. 7099377 demonstrates a WCDMA-TDD system.
  • a scrambling code which is a long pseudo noise code sequence is associated with each base station and permits to distinguish the base stations from each other.
  • an orthogonal variable spreading factor code is allocated to each remote terminal (such as cellu- lar mobile phone) . All these OVSF codes are orthogonal to each other, which permits to distinguish a remote terminal from another.
  • a problem inherent with TDD communications is its sensitivity to interference between uplink and downlink communications. Particularly, this is a problem if the downlink and uplink communications are controlled by different opera- tors. If a nearby interfering user transmits in uplink direction, downlink communications received by an interfered user are generally of a smaller received signal level than the interference received from the nearby interfering user, thereby destroying downlink reception.
  • the abovementioned interference problem is generally solved by separating the various frequency bands, used by different operators, by allocating particular guard bands in frequency domain, thereby reducing or eliminating the interference between the different bands of communica- tion including interference between uplink communications of one operator with downlink communications of another.
  • the allocation of frequency guard bands is schematically illustrated in figure 2.
  • frequencies are grouped in blocks «A1», «A2», «A3», «Bl», «B2», «B3» allo- cated to two different operators «A», «B».
  • two of the groups «A1», «B1» form a guard band.
  • the guard band needs not be allocated to particular one or more operators.
  • the bands used for communications «A2», «A3», «B2», «B3» are used for communications in both uplink and downlink directions.
  • Dividing frequency band to be used partly for unidirectional communications, e.g. downlink communications, and partly for bi-directional communications eliminates or reduces substantially the risk of interference between commu- nications in downlink and uplink directions and enables control of interference between two operators using the unidirectional part of the band for communications in one direction within allocated fractions of the unidirectional part of the band, thereby relieving the requirement on guard band allocation.
  • the division need not be completely disjoint if transmissions are controlled or limited.
  • some transmission power for control purposes is allowed according to an embodiment of the invention, despite the fact that this transmission power is sent in a direction opposite from the dedicated transmission direction of the frequency range in which it is transmitted. This can be allowed due to controlled im- pact of the transmissions.
  • guard bands in order to reduce or eliminate cross-direction interference can be reduced or eliminated, with the apparent advantage of a limited nature resource being more efficiently used than otherwise.
  • Figure 1 illustrates schematically a radio communications system according to prior art.
  • Figure 2 illustrates allocation of frequency guard bands in an example TDD system according to prior art.
  • Figure 3 demonstrates schematically frequency bands allocated to unidirectional communications according to the in- vention.
  • Figure 4 demonstrates frequency band allocation according to an embodiment of the invention where operations include control signaling required to be included in the upper range of each operator's transmission range.
  • FIG. 5 illustrates frequency allocation according to an additional embodiment of the invention.
  • Figure 6 shows schematically a flowchart of channel allocation for a method of guard band reduction according to the invention.
  • Figure 7 illustrates a communications node comprising processing means adapted to the invention.
  • Figure 8 illustrates example allocation of downlink and uplink frames according to the invention.
  • a common frequency band for uplink and downlink transmissions dividing the different communications directions in e.g. time-domain has an advantage as regards utilization of un-paired frequency spectrum, making it easier to find frequency spectrum useful for interna- tional or world-wide communications systems in accordance with international frequency plans.
  • a common frequency band for uplink and downlink transmissions also facilitates improved adaptation to varying channel parameters due to channel reciprocity, providing similar or identical proper- ties for uplink and downlink transmissions.
  • a drawback of separating communications directions solely in the time-domain is an increased risk of interference be- tween uplink and downlink communications directions, particularly interference between uplink communications of one operator and downlink communications of another, due to out-of-band transmission power.
  • interference In a non-ideal world, there is a small amount of transmission power dissipating out of an operator's desired or allocated frequency band, thereby affecting adjacent frequencies.
  • a main reason for this interference being a problem is the different distances to the receiver from transmitters transmitting de- sired signals and interfering signals, respectively.
  • One well-known means of reducing interference, in addition to specifying allowable and reasonable out-of-band energy or transmission power, is to introduce guard bands. Guard bands, however, allocate valuable frequency resources and blocks the frequency space which otherwise could have been used for communications .
  • Advantageous reduction of inter-operator guard band and/or interference is preferably achieved according to the invention by separating communications between different commu- nications directions, which may interfere between the different operators, in a domain in addition to the time- domain.
  • frequency division multiplex FDM
  • FDM frequency division multiplex
  • OFDMA or SC-FDMA is applied for channel access.
  • allocation and scheduling of transmissions reduce or eliminate uplink traffic transmis ⁇ sions in a particular part or interval of the carrier fre ⁇ quency range, such as the upper or lower part of the car- rier frequency range.
  • the invention is also applicable to a TDD operator which is frequency neighbor of another operator e.g. allocating a neighboring frequency interval for uplink or downlink com- munications .
  • the neighboring operator allocates a frequency band next to the TDD operator's allocated band for downlink communications
  • the TDD operator applies transmission restrictions on downlink transmissions in a frequency range next to the neighboring operators allocated band, and possibly entirely eliminates downlink transmissions in the particular frequency range, in order to reduce frequency space otherwise allocated for guard band.
  • the neighboring operator allo- cates a frequency range next to the TDD operator's allocated band for uplink communications
  • the TDD operator applies transmission restrictions on TDD uplink transmissions in a frequency range next to the neighboring operator's allocated band.
  • bandwidth allocation is a further means to provide additional downlink capacity while limiting or eliminating particularly inter-operator interference, and thereby further improving system performance.
  • FIG. 3 illustrates schematically a TDD carrier which in effect can be specified using FDD terminology.
  • Data blocks sent on frequencies well separated in frequency domain be ⁇ tween different operators «AII», «AIII», «BII», «BIII» can be used for bi-directional communications or uplink commu ⁇ nications and adjacent frequencies of the two operators «AI», «BI» are used for downlink communications.
  • the exam ⁇ ple frequency range between 3500 and 3584 MHz is just an example and is not intended to limit the invention.
  • each mobile station is dynamically scheduled on different points in the orthogonal domain, e.g. onto different frequency components, also called tones, for OFDM forming the orthogonal domain for various transmission instants.
  • a mobile station For OFDM, a mobile station is generally scheduled for a plurality of tones for each transmission instant. This holds for both uplink and downlink transmissions in general. Some downlink transmissions, e.g. due to bandwidth requirements or availability, are allocated a particular downlink frequency band with downlink transmissions in only one direction.
  • processing means of the central anchor nodes «Central Anchor» are preferably adapted for channel alloca- tion in accordance with the invention.
  • the invention is of value also if not all anchor nodes of a communications system implement the invention. However, the risk of interference then increases unless anchor nodes not implementing the invention reserve guard bands in accordance with prior art.
  • FIG. 4 illustrates such a situation, where operations include control signaling re- quired to be included in the upper range of each operator's transmission range.
  • restrictions on the control signaling non-exclusively e.g. including equivalent isotropic radiated power, transmission power spectral den ⁇ sity or transmission intermittence . Due to the restric- tions imposed, it is possible to both eliminate or reduce guard band between operators and eliminate or reduce interference between uplink and downlink directions, and par ⁇ ticularly interference between operators .
  • Figure 5 illustrates frequency allocation according to an additional embodiment of the invention.
  • a frequency band «AI», «BI» is subject to transmission power limitation «RI» in order to eliminate interference between downlink and up- link directions with no or small guard bands between operators.
  • an uplink response channel «RI» of very limited transmission spectral density will not significantly affect downlink transmissions «AI», «BI» for the operators and radio technology of interest due to the limited transmission spectral density of the uplink transmissions «RI».
  • a flowchart of channel allocation for a method of guard band reduction according to the invention is schematically illustrated in figure 6.
  • channel resources are allocated to either or both of a first and second example frequency ranges or groups of frequency ranges.
  • downlink, DL, direction is used as an example direction of two duplex directions merely for illustration of a communications direction for which conditions on transmissions are less restricted.
  • the invention does not exclude that the roles of uplink and downlink directions are interchanged, e.g. if greater capacity in uplink direction than in downlink direction is preferred. However, according to registered load with most users, there is generally a greater need for capacity in downlink direction than in uplink direction.
  • the method according to the invention can preferably be distributed in the form of a computer program product stored on any suitable me ⁇ dium, such as one or more optically readable disks, mag ⁇ netically readable disks or memories such as read-only or random access memories .
  • the computer program product is preferably installed in a control node of a communications system, e.g. a radio network controller in UMTS or a Central Anchor in LTE (long-term evolution), operating accord- ing to the invention.
  • All frequency ranges are available for allocation, typically controlled by a MAC (Media Access Control) layer of control node, to transmissions of the communications direction which is less restricted in relation to other opera- tors (in the example the downlink, DL, direction) «S2».
  • the more restricted communications direction (uplink direction) is limited to allocations in one or more example second frequency ranges «S3».
  • Figure 7 illustrates in principle processing means « ⁇ » of a communications node «Communications Node», the processing means being particularly adapted to the invention, e.g., by means of an installed computer program product, preferably stored in memory means «M», the processing means allocating channels as described above.
  • the memory means can be inte- grated in the same physical entity as the processing means or be a separate memory or storage means connected to the processing means such that stored data can be accessed.
  • input/output means «1/0» for interconnecting other one or more nodes .
  • the frame structure of uplink and downlink transmissions is maintained similar to a system not implementing the invention. Consequently, no uplink frames are scheduled for the particular downlink frequency band in the example with such a particular frequency band.
  • Figure 8 illustrates example allocation of downlink and uplink frames according to an embodiment of the invention.
  • Scheduling information is preferably provided in the beginning of a downlink frame.
  • the scheduling information indicates which one or more frequencies are allocated to each user during a particular time interval .
  • the scheduling information provided in the downlink frame also indicates to a mobile station or user equipment which frequencies are exclusively reserved for downlink transmission and should not be used for uplink transmissions .
  • receiver and transmitter properties of, e.g., a user equipment are general in nature.
  • the use of concepts such as user equipment, UE, adaptive multilayer, AML, WiMAX or WCDMA within this patent application is not intended to limit the invention only to devices associated with these acronyms. It concerns all devices operating correspondingly, or being obvious to adapt thereto by a person skilled in the art, in relation to the invention.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention concerne des systèmes de communication comprenant des technologies duplex à répartition dans le temps, et elle concerne plus particulièrement l'allocation de communications de liaison montante et de liaison descendante dans de tels systèmes de communication dans un domaine orthogonal, comme un domaine fréquentiel.
PCT/SE2008/050128 2007-02-28 2008-01-31 Allocation de transmission de liaison montante et de liaison descendante dans tdd dans un domaine orthogonal. Ceased WO2008105718A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0700508 2007-02-28
SE0700508-5 2007-02-28

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WO2008105718A1 true WO2008105718A1 (fr) 2008-09-04

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2521408A4 (fr) * 2009-12-31 2016-01-20 Zte Corp Procédé de communication en duplex, procédé et système de planification de terminal
EP3026973A1 (fr) * 2011-04-13 2016-06-01 Google Technology Holdings LLC Procédé et appareil pour détecter la configuration de bande passante de transmission d'un canal en liaison avec réduction des interférences entre canaux dans des systèmes de communication sans fil
US9729304B2 (en) 2012-09-27 2017-08-08 Telefonaktiebolaget Lm Ericsson (Publ) Methods and devices for radio communication configuration
US10313995B2 (en) 2015-08-31 2019-06-04 Samsung Electronics Co., Ltd. Apparatus and method for operating radio access technology in communication system supporting time division duplexing scheme
US11206705B2 (en) 2018-07-23 2021-12-21 At&T Mobility Ii Llc Flexible carrier downlink and uplink pairing for advanced networks

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7151795B1 (en) * 2001-12-31 2006-12-19 Arraycomm Llc Method and apparatus for increasing spectral efficiency using mitigated power near band-edge
WO2007146017A2 (fr) * 2006-06-06 2007-12-21 Sr Télécom & Co, S.E.C. Utilisation de la bande garde entre des systèmes sans fil fdd et tdd

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7151795B1 (en) * 2001-12-31 2006-12-19 Arraycomm Llc Method and apparatus for increasing spectral efficiency using mitigated power near band-edge
WO2007146017A2 (fr) * 2006-06-06 2007-12-21 Sr Télécom & Co, S.E.C. Utilisation de la bande garde entre des systèmes sans fil fdd et tdd

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
HOLMA H. ET AL.: "Interference Considerations for the Time Division Duplex Mode of the UMTS Terrestrial Radio Access", IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, vol. 18, no. 8, August 2000 (2000-08-01), XP011055185 *
POVEY G.J.R. ET AL.: "TDD-CDMA Extension to FDD-CDMA Based Third Generation Cellular System", pages 813 - 817, XP002138091 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2521408A4 (fr) * 2009-12-31 2016-01-20 Zte Corp Procédé de communication en duplex, procédé et système de planification de terminal
EP3026973A1 (fr) * 2011-04-13 2016-06-01 Google Technology Holdings LLC Procédé et appareil pour détecter la configuration de bande passante de transmission d'un canal en liaison avec réduction des interférences entre canaux dans des systèmes de communication sans fil
US9565655B2 (en) 2011-04-13 2017-02-07 Google Technology Holdings LLC Method and apparatus to detect the transmission bandwidth configuration of a channel in connection with reducing interference between channels in wireless communication systems
US9729304B2 (en) 2012-09-27 2017-08-08 Telefonaktiebolaget Lm Ericsson (Publ) Methods and devices for radio communication configuration
US10313995B2 (en) 2015-08-31 2019-06-04 Samsung Electronics Co., Ltd. Apparatus and method for operating radio access technology in communication system supporting time division duplexing scheme
US11206705B2 (en) 2018-07-23 2021-12-21 At&T Mobility Ii Llc Flexible carrier downlink and uplink pairing for advanced networks

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