(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2009/0067377 A1
`TALUKDAR et al.
`(43) Pub. Date: Mar. 12, 2009
`
`
`US 20090067377A1
`
`(54) MEDIUM ACCESS CONTROL FRAME
`STRUCTURE IN WIRELESS
`COIVIIVIUVICATION SYSTEM
`
`(22)
`
`Filed:
`
`Aug. 13, 2008
`
`Related US. Application Data
`
`(75)
`
`Inventors:
`
`ANUP K. TALUKDAR, Dekalb,
`it, (US); MARK C. CUDAK,
`ROLLING MEADOWS, IL (US);
`KEVIN I1. BAUIVI, ROLLING
`MEADOWS, IL (US); AMITAVA
`GHOSH, BUFFALO GROVE, II,
`(US); STAVROS TZAVIDAS,
`EVANSTON, II, (US); FAN
`WANG. VERNON HILLS. IL
`(US); HUA XU, LAKE ZURICH,
`IL (US); XIANGYANG ZHUANG,
`Lake Zurich, IL (US)
`
`Correspondence Address:
`MOTOROLA INC
`600 NORTH US HIGHWAY 45, W4 - 39Q
`LIBERTYVILLE, IL 60048-5343 (US)
`
`(73) Assignee:
`
`MOTOROLA, INC.,
`IIBERTYVILLE, H, (US)
`
`(21) Appl. No.:
`
`12/191,042
`
`(60) Provisional applicalion No. 60/95 6,031, filed on Aug.
`15, 2007.
`
`Publication Classification
`
`(51)
`
`Int.Cl.
`(2009.01)
`1104W 72/04
`(52) U.S.Cl. .......................................... 370/329
`
`(57)
`
`ABSTRACT
`
`A Wireless communication infrastructure entity configured to
`allocate radio resources, in a radio frame, to a Wireless termi-
`nal compliant with a first protocol and to a Wireless terminal
`compliant with a second protocol. The radio frame including
`a first protocol resource region and a second protocol resource
`region. The radio frame including a first protocol allocation
`control message that allocates resources Within the first pro—
`tocol resource region to the Wireless terminal compliant with
`the first protocol, and a second protocol allocation control
`message that allocates resources Within the second protocol
`resource region to the Wireless terminal compliant with the
`second protocol.
`
`M
`
`103
`
`BASE UNIT
`
`REMOTE UNIT
`
`
` REMOTE UNIT
`BASE UNIT
`
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`Patent Application Publication Mar. 12, 2009 Sheet 1 of 14
`
`US 2009/0067377 A1
`
`M
`
`103
`
`REMOTE UNIT
`
`BASE UNIT
`REMOTE UNIT BASE UNIT
`
`110
`
`FIG. I
`
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`Patent Application Publication Mar. 12, 2009 Sheet 2 of 14
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`US 2009/0067377 A1
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`
`2.5 msec
`
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`Patent Application Publication Mar. 12, 2009 Sheet 3 of 14
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`US 2009/0067377 A1
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`Patent Application Publication Mar. 12, 2009 Sheet 4 of 14
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`US 2009/0067377 A1
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`Patent Application Publication
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`Mar. 12, 2009 Sheet 6 of 14
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`Patent Application Publication
`
`Mar. 12, 2009 Sheet 7 of 14
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`US 2009/0067377 A1
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`Patent Application Publication Mar. 12, 2009 Sheet 8 of 14
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`US 2009/0067377 A1
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`Patent Application Publication
`
`Mar. 12, 2009 Sheet 9 of 14
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`US 2009/0067377 A1
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`Patent Application Publication Mar. 12, 2009 Sheet 10 0f 14
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`US 2009/0067377 A1
`
`
`
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`atent pplication Publication Mar. 12, 2009 Sheet 11 0f 14
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`US 2009/0067377 Al
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`Patent Application Publication Mar. 12, 2009 Sheet 12 of 14
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`US 2009/0067377 A1
`
`F m
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`Patent Application Publication Mar. 12, 2009 Sheet 13 of 14
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`US 2009/0067377 A1
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`FRAME n+2 VIII/A
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`Patent Application Publication Mar. 12, 2009 Sheet 14 of 14
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`US 2009/0067377 A1
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`FRAME n+2
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`US 2009/0067377 A1
`
`Mar. 12, 2009
`
`MEDIUM ACCESS CONTROL FRAME
`STRUCTURE IN WIRELESS
`COMlVIUNICATION SYSTEVI
`
`FIELD OF THE DISCLOSUR:LU
`
`
`
`[0001] The present disclosure relates generally to wireless
`communications and more specifically to medium access
`control frame structures in wireless communication systems
`with improved latency support.
`BACKGROUND
`
`[0002] An important consideration for advanced wireless
`communication systems is one—wa y air—interfa ce latency. Air-
`interface latency is primarily dependent on the Medium
`Access Control (MAC) frame duration. In the developing
`IEEE 802.16m protocol, for example, the proposed target
`latency is less than approximately 10 msec and some ob serv-
`ers have suggested that a much lower latency may be required
`to compete with other developing protocols, for example,
`
`with 3GPP Long Term Evolution (LTE). The IEEE 802.16m
`protocol is an evolution of the WiMAX-OFDMA specifica-
`tion for the IEEE 802.16e protocol. However, the legacy
`lEEE 802.16e 'l'DD frame structure has a relatively long
`duration and is incapable of achieving the latency targets set
`for IEEE 802.16m.
`[0003] Evolutionary wireless communication systems
`should also support for legacy system equipment. For
`example, some IEEE 802.16e and IEEE 802.16m base sta-
`
`tions and mobile stations are likely to coexist within the same
`
`
`network while upgrading to the newer system. Thus 1.1;;
`
`
`
`802.16e mobile stations should be compatible with I3 3 3
`802.16m base stations, and 1131313. 802.16e base stations
`should support IEEE 802.16m mobile stations. 'l'hus frame
`structures for air-interfaces are proposed with a view to
`achieving lower latency and in some embodiments to main-
`taining backward compatibility.
`[0004] A legacy system is defined as a system compliant
`
`
`with a subset of the WirelesslVLAN—OFDMA capabilities
`
`
`specified by I 3
`3 802. 16-2004 (specification IEEE Std 802.
`16-2004: Part 16. IEEE Standard for Local and metropolitan
`area networks: Air Interface for Fixed Broadband Wireless
`Access Systems, June 2004) and amended by IEEE 802.16e-
`2005 (IEEE Stc. 802.16e-2005, IEEE Standard for Local and
`metropolitan area networks, Part 16: Air Interface for Fixed
`and Mobile Broadband Wireless Access Systems, Amend-
`ment 2: Physical and Medium Access Control Layers for
`Combined Fixed and Mobile Operation in Licensed Bands,
`
`
`and IEEE Std. 802.16-2004/C0r1-2005, Corrigendlun 1,
`
`
`December 2005) and I 3 3 3 802.16Cor2/D3, where the subset
`
`is defined by WiMAX 3orum Mobile System Profile, Release
`1.0 (Revision 1.4.0: 2007-05-02), excluding specific fre-
`quency ranges specified in the section 41.12 (Band Class
`Index).
`[0005] The various aspects, features and advantages of the
`disclosure will become more fully apparent to those having
`ordinary skill in the art upon careful consideration of the
`following Detailed Description thereof with the accompany-
`ing drawings described below. The drawings may have been
`simplified for clarity and are not necessarily drawn to scale.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`
`
`FIG. 1 is a wireless communication system.
`[0006]
`FIG. 2 is a legacy protocol frame mapped to a next
`[0007]
`generation 1:2 sub—frame.
`[0008]
`FIG. 3 is a frame structure configuration having a
`75% duty cycle.
`
`
`
`3 G. 4 is another frame structure configuration hav-
`[0009]
`ing a 25% duty cycle.
`[0010]
`3 G. 5 is a super-frame structure configuration.
`[001]]
`3 G. 6 is a frame having multiple sub—blocks of
`equal duration.
`[0012]
`3 G. 7 is another frame having multiple sub—blocks
`of equal duration.
`[0013]
`3 G. 8 is a frame having multiple sub-blocks of
`equal duration.
`[0014]
`3 G. 9 is a super—frame comprising multiple frames
`of equal duration.
`[0015]
`3 G. 10 is an exemplary hybrid frame structure.
`[0016]
`3 G 11 is a frame having first and second protocol
`resource regions.
`[0017]
`3 G 12 is another frame having first and second
`protocol resource regions.
`[0018]
`3 G 13 is a frame having first and second protocol
`resource regions.
`[0019]
`3 G 141s a frame having first and second protocol
`resource regions.
`[0020]
`3 G 151s a lrame having first and second protocol
`resource regions.
`[0021]
`3 G. 16 is a sequence of radio frames having first
`and second resource regions.
`[0022]
`3 G. 17 is another sequence of radio frames having
`first and second resource regions.
`[0023]
`3 G. 18 is another sequence of radio frames having
`first and second resource regions.
`
`
`
`
`D 3 lAIL 3D DESCRIPTION
`
`
`
`In FIG. 1, the wireless communication system 100
`[0024]
`includes one or more fixedbase infrastructure units forming a
`network distributed over a geographical region. A base unit
`may also be referred to as an access point, access terminal,
`Node—B, eNode—B, or by other terminology used in the art.
`The one or more base units 101 and 102 serve a number of
`remote units 103 and 110 within a serving area, for example,
`a cell, or within a cell sector. The remote units may be fixed or
`terminal. The remote units may also be referred to as sub—
`scriber units, mobile stations, users, terminals, subscriber
`stations, user equipment (UE), terminals, or by other terrni—
`nology used in the art.
`[0025] Generally, base units 101 and 102 transmit down-
`link communication signals 104 and 105 to serving remote
`units on at lea st a portion of the same resources (time and/or
`frequency). Remote units 103 and 110 commtmicate with the
`one or more base units 101 and 102 via uplink communication
`signals 106 and 113. The one or more base units may com-
`prise one or more transmitters and one or more receivers that
`serve the remote units. The remote units may also comprise
`one or more transmitters and one or more receivers.
`[0026]
`In one embodiment, the conmiunication system uti-
`lizes OFDMA or a next generation single—carrier (SC) based
`FDMA architecture for uplink transmissions, such as inter-
`leaved FDIVJA (IFDMA), Localized FDMA (Ll-'DMA),1)13"1'—
`spread OFDM (DFT—SOFDM) with IFDMA or LFDMA. In
`OFDM based systems, the radio resources include OFDM
`symbols, which may be divided into slots, which are group-
`ings of sub—carriers. A11 exemplary OFDM based protocol is
`IEEE 802.16(e).
`[0027] Generally, the wireless communication system may
`implement more than one conmiunication technology as is
`typical of systems upgraded with newer technology, for
`example, the evolution of GSM to UMTS and future UMTS
`
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`Mar. 12, 2009
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`
`
`
`
`releases thereof. In FIG. 1, for example, one or more of the
`
`
`base units 101 may be legacy technology base stations, for
`example, 14 4 4 802.16(e) protocol base stations, and other
`base station may be newer generation technologies, for
`example, 1333 802.16(m) protocol base stations. In these
`cases, it is generally desirable for the new technologies to be
`backward compatible with the legacy technology For the
`evolution of BBB 802.16(e), the backward compatibility
`constraint
`implies that
`the legacy frame structure,
`for
`example, the 5 msec duration 802.16(e) frame, must be sup-
`ported by 802.16(m) base stations. Additionally, in order to
`efficiently support delay sensitive applications, 802.16(m)
`base stations should be able to service both 802.l6(m) and
`legacy terminals within the connnon frame structure.
`[0028] Regarding frame structure, it is generally necessary
`to design frames having a relatively short duration in order to
`reduce latency. Thus to deliver low latency in 802.16m sys-
`tems with backward compatibility, it is necessary to develop
`a sub—frame structure based on the legacy 802.16(e) frame. In
`order to address the latency requirements, it is necessary to
`design frames with shorter than 5 msec duration. However, to
`efficiently serve legacy traffic, it is also necessary that 802.
`l6(mi) systems have 5 msec legacy frames. Thus two broad
`classes of frames would be required for an 802.16(m) system
`having reduced latency and support for legacy 802.l 6(e)
`devices. The first class includes a full-frame (having a 5 msec
`duration) with one DL interval and one UL interval similar to
`the 802.16(e) TDD legacy frames. The second class offrames
`includes a sub-frame. For example, a 5 msec frame having N
`DL intervals andN UL intervals. This frame may also contain
`N transmit/receive transition gap (TTG) and receive/transmit
`transition gap (RTG) intervals. N could be kept small, typi-
`cally N:2, in order to limit TTG and RTG related overhead.
`According to this exemplary scheme, the legacy 802.16(e)
`TDD frames can only be a full-frame and the 802.16(m)
`frames are preferably sub—frame 1:2, althoughthey could also
`be full-frames. The h-frames can be either full-frame or sub-
`frame 1:2. FIG. 2 illustrates an 802.16(m) sub—frame 1:2 that
`is backwards compatible with a legacy 802 . l 6(e) TDD frame,
`wherein the first and third blocks are downlink blocks and the
`second and fourth blocks are uplink blocks. In general, the
`length of the intervals ofthe blocks can be different.
`[0029] The 802.16(m) 5 msec frame can be perceived to be
`composed of following types of basic regions: e—DL region
`used for transmission of downlink traffic to 802.16(e) tenni-
`nals; e—UL: region allocated for transmission of data and
`control messages by 802.16(e) terminals; m-DL: region allo-
`cated for transmission to 802.l6(m) terminals; and iii—UL:
`region allocated for transmission by 802.16(m) terminals.
`The e—DI, and e—UI, regions can also be used for transmis-
`sions to/from 802.16(m) terminals. In general, the structures
`of the 802.16(m) region (sub—channel and pilot structures)
`can be different from those of the 802. 16(e) regions. Depend-
`ing on the population of legacy and newer generation termi-
`nals, it may be necessary to allocate the entire 5 msec frame
`for 802.16(e) services or 802.16(111) services.
`[0030] Using these different types ofregions, various types
`of 5 msec frame structures can be created to suit the traffic
`service requirements. These are: e-frames composed of only
`e-DL and e-UL regions used to serve legacy 802.16(e) TDD
`terminals (802.16(m) tenninals can also be served in these
`frames in legacy mode); m—frames composed of m—DL and
`m-UL regions only for serving only 802.16(m) terminals;
`h-frames containing both e-DL/e-UL and m-DL/m-UL
`
`
`
`
`
`regions for serving 802.16(e) and 802.16(m) tenninals. The
`802.16(111) portion and the 802.16(e) portion should be time
`division multiplexed so that the 802.16(m) control channel,
`pilot, and sub-channelization can provide flexibility.
`[0031] Depending on the device type population and traffic
`pattern, it may be necessary to treat an m-frame or an h-frame
`as a legacy Virtual frame in a cell/sector. The m—DI, and m—I II,
`regions in these frames may have different sub-chamiel/pilot
`structures than the legacy systems; those regions need to be
`treated as “dead zones”, which the legacy terminals should
`not use. The full—frame, being similar in structure to the
`legacy 802.16(e) frame, can be easily mapped to a legacy
`virtual frame with full utilization of the frame resources.
`However, the sub-frame lzN, which can also be mapped to
`legacy 802.16(e) virtual frame, will contain “dead zone(s)”
`where no 802.16(e) (TDD) transmission can be allowed to
`ensure DL/UL synchronization.
`[0032] An 802.16(m) base unit can provide service to
`legacy 802.16(e) tenninals in full-frames. To provide service
`in the sub-frame IN, the 802.16(m) base unit can map a
`legacy virtual 5 msec frame to N adjacent sub-frames and the
`train of sub—frames can be organized as a train of legacy 5
`msec virtual frames. There are N choices for the time division
`duplex frame (TDD) split position in a legacy virtual frame.
`The system wide synchronization requirement for the TDD
`system imposes additional constraints on the downlink and
`uplink transmission intervals, creating dead zones during
`which no transmission should be done to and from legacy
`802.16(e) TDD terminals. However, transmissions to and
`from 802.16(111) terminals are possible in these dead zones.
`FIG. 3 illustrates a first configuration wherein a legacy 802.
`16(e) TDD terminal encounters a 5 msec frame having a 75%
`duty cycle. The frame includes a legacy preamble 302, a DL
`map 304, and a dead zone 306 during which there is no legacy
`downlink allocation during the 802.16(m) uplink interval.
`FIG. 4 illustrates a second configuration wherein the frame
`includes a dead zone 406 during which there is no legacy
`uplink allocation during the 802.16(m) downlink interval.
`[0033] A generic message structure and its parameters to
`indicate a dead zone is shown in Table l.
`
`TART F. 1
`
`Message parameter for dead zone indication
`Parameter
`value
`
`location
`dedicated pilot tag
`
`<symbol number>/<Li.[ne>
`0 or 1
`
`In the above message, the parameter “loca tion" indi—
`[0034]
`cates a position within the frame in time (which may be
`denoted by the symbol number within the frame or absolute
`time or time offset from the start of the frame or offset from
`some other specified time); the interpretation ofthe parameter
`“location” depends on the value of the parameter “dedicated
`pilot tag”. If“dedicated pilot tag” is l, the pilot symbols after
`“location” are dedicated; if it is 0, it indicates that the pilot
`symbols after the “location” are not dedicated pilots. Thus a
`zone with dedicated pilots can be described by two occur-
`rences of this message: the first message With dedicated pilot
`tag:1 and location:“T1”, followed by a 2"” message with
`dedicated pilot tag:0 and location:“T2”, where T2>:T1; a
`legacy terminal which has been allocated resources within
`this zone should use only pilots within its burst for cham1el
`
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`estimation. A legacy terminal which has not been allocated
`resources within this zone will ignore the pilots in this zone
`and also it will not need to decode any of the data transmis-
`sions within the dedicated pilot zone. This combined with the
`BS not making an allocation to any 16e mobile in the zone
`indirectly disables or isolates the 16e mobiles from this zone.
`Thus, 16e mobile effectively ignores whatever is in the zone.
`[0035] An example mes sage which can be used for indicate
`(lead zones is the STC_DL_ZONE_1E( ,) of IEEE 802.16e
`specification; the parameters “OFDMA symbol offset” and
`“Dedicated pilots” in this message corresponds to the param-
`eters “location” and “dedicated pilot tag” in the above generic
`message in Table l.
`[0036] Another message structure and its parameters which
`can be used to implement dead zones are shown in Table 2.
`
`TABLE 2
`
`Dead zone message t_vpe 2
`value
`
`Parameter
`
`<symbol number>/<time>
`Starting symbol
`Starting subechnnnel <subecarrier number>/<subechannel nurnber>
`Symbol count
`<Number of symbols>/<duration in time>
`Sub-channel co LLlll.
`<nurnber ofsub-carriers>/<nuniber ofsub-
`channels>
`
`[0037] The four parameters describe a rectangular dead
`7one of time—frequency resources.
`In this message,
`the
`parameter “starting symbol” indicates a position within the
`frame in time (which may be denoted by the symbol number
`within the frame or absolute time or time offset from the start
`of the frame or offset from some other specified time) where
`the dead zone begins; “symbol count” indicates the duration
`of the dead zone, starting from the “starting symbol”. The
`parameter “starting sub-channel” indicates the location in thc
`sub-carrier frequency where the dead zone begins; this is in
`units of sub-carrier or sub-channel, which is a group of sub-
`carriers; “sub-channel coun ” indicates the length ofthe dead
`zone in the frequency dimension. An example of this generic
`message type is the PAPR_Reduction_and_Safety_Zone_
`Allocation_lE( ) of the IEEE 802.16e specification. In this
`message, the parameters “OFDMA_symbol_offset”, “Sub-
`channel offset”, “No. OFDMA symbols” and “No. sub-chan-
`nels” corresponds to the parameters “starting symbol”, “start-
`ing sub-channel”, “symbol count” and “sub—channel count”
`of the generic dead zone message type 2, respectively; the
`PAPR_Reduction_Safety_Zone parameter in the PAPR_Re-
`duetioniandisafety7Zone7AllocationilE( ) should be set to
`“l” to indicate a reduced interference zone to the legacy
`terminal; this will effectively direct the terminal not to per-
`form airy uplink transmission in that zone.
`[0038]
`Striking a balance between efficient legacy support
`and low-latency 80216011) service is challenging with a
`homogeneous frame size. The full-frames discussed above
`provide efficient legacy support while sacrificing latency per-
`formance for 802.16(m) terminals. The sub-frames provide
`low—latency support for 802.16(m) terminals while sacrific-
`ing capacity for legacy terminals in the form of dead zones.
`[0039]
`In one embodiment. a heterogeneous configuration
`contains both full-frames and sub-frames, wherein the full-
`frames and sub-frames are interleaved over time. Within a
`cell, the full—frames are primarily used for serving legacy
`terminals present in the cell, whereas the sub-frames are
`primarily used to serve the 802.1 6(111) terminals. However, for
`
`servicing packets with urgent delay constraints, either frame
`type can be used to service either type of terminal. The full-
`framcs and the sub-frames are organized in a repeating pat-
`tem, called a super-frame.
`[0040]
`lnthc super-frame ofFIG. 5. the interlcavingpattcrn
`consists of two sub—fraines 1:2 followed by one full—frame.
`This pattern is generally the same over all sector/cells. The
`first super-frame contains an 802.16(e) TDD virtual frame
`configuration with 75% duty cycle and the 2"“ super-frame
`contains a 802.16(e) TDD virtual frame configuration with
`25% duty cycle. Generally. for the same 802.16(e) TDD
`Virtual fi‘ame, the configuration options can be different for
`different base stations. One base station may employ the
`802.16(e) virtual frame to communicate with a legacy termi-
`nal while another neighboring base station may employ a 16m
`Sub-frame 1:2 structure to communicate with a 16m base
`station without any undesired interference between uplink
`and downlink transmissions. The proportion of the different
`types offrames and their interleaving pattern in a super—frame
`is generally determined by the proportion of 802.16(e) and
`80216011) terminals in the system. The configurations may
`be implemented on a system-wide basis to ensure that there is
`no conflict between base unit transmission and reception in
`adjacent cells (e.g., no conflict in TDD Tx/Rx boundaries
`among adjacent cells).
`[0041] Thus a next generation wireless communication
`infrastructure entity, for example, an 802.] 6(m) base unit in
`FIG. 1, would transmit a super-frame including a plurality of
`frames wherein each frame includes at least two regions. The
`regions are generally some sort of resource that may be allo-
`cated to the terminals for uplink or downlink communications
`in the case of a TDD system. The super-frames are generally
`transmitted in a sequence. This superframe structure must be
`communicated to all base stations in a TDD system to main-
`tain synchronization of all sectors and cell in order to ensure
`that there is no conflict between base unit transmission and
`reception in adjacent cells. This structure may be communi-
`cated in a control message specifying a configuration charac—
`teri stic ofthe regions within each frame ofa super-flame. The
`control message may be transmitted to other base stations
`over the land line network or by other means such as radio
`communication links between the base stations. This control
`message may also be transmitted to terminals in at least one
`frame of the superframe. The message may specify the con—
`figuration characteristic of regions within each frame of the
`same super—frame in which the message occurs, or in the
`frames of another super-frame, for example a sub sequent
`super-frame. In one embodiment, the configuration charac—
`teri stic of the regions within each frame ofthe super-frame is
`specified in a control message map or by other means. In any
`case, in some embodiments, the control message may contain
`a reference number specifying the map applicable for the
`super-frame,
`thereby enabling terminals
`to distinguish
`among versions of the control message containing the con—
`figuration characteristic.
`[0042]
`In one embodiment, the configuration characteristic
`ofthe regions is selected from a group comprising: a number
`regions; region size; region type (e.g., uplink or downlink for
`a TDD system); and the ordering of the regions. Multiple
`characteristics may also be specified. In one embodiment, for
`a TDD system, the control message specifies whether the
`regions of the frame are uplink regions or downlink regions.
`Thus the regions are selected from a group of regions com-
`prising: an uplink region and a downlink region. The control
`
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`message may also specify the number of uplink regions or
`downlink regions within each frame of a super-frame.
`I11
`some embodiments, the control message specifies a size of
`uplink regions or downlink regions within each frame of a
`super-frame. In FIG. 5, the frames generally have different
`numbers ofresourceblocks (a resource block is a downlink or
`uplink transmission interval). For example, the first and sec-
`ond 5 msec sub-fi‘ames have four resource blocks, and the
`third 5 msec sub—frame has two blocks.
`
`[0043] There are various ways to configure frames that
`provide legacy compatibility and reduce latency based on the
`proposed framework. Another factor to consider in the design
`ofa new protocol frame structure is support for both TDD and
`FDD. Preferably, similar frame and sub-frame structures can
`be applied for both TDD and FDD.
`[0044]
`In one embodiment, a frame is divided into multiple
`blocks of equal size, wherein the blocks may support one or
`more protocols, for example, IEEE 802.16(e) and/or 802.16
`(n1). Such a frame would enable an 802.l6(m) wireless com-
`munication infrastructure entity to allocate radio resources to
`both 802.16(e) and 802.l6(m) wireless terminals. Generally,
`the radio frame includes a plurality ofhlocks, including a first
`block and last block, wherein each block comprises a plural-
`ity of symbols In one embodiment, each block comprises
`substantially the same number of symbols. The first block
`includes a first protocol preamble, for example, a legacy
`protocol preamble like 802.l6(e). The remaining blocks in
`the frame are devoid of the first protocol preamble.
`[0045] Generally, the radio frame includes at least one first
`protocol block and/or at least one second protocol block, for
`example, 802.l6(e) and/or 802.l6(m) blocks.
`In some
`embodiment, the frame includes both first and second proto-
`col blocks. In another embodiment, the frame includes only
`second protocol blocks, for example, 802.16(m) blocks. The
`radio frame includes an allocation control message for allo-
`cating resources within a protocol block. In frames that
`include first and second protocol blocks,
`the radio frame
`includes a first protocol allocation control message for allo-
`cating resources in the first protocol block, and a second
`protocol allocation control message for allocating resources
`in the second protocol block. In one embodiment, the alloca-
`tion control message is a first protocol allocation control
`message for allocating resources within a first protocol block
`of a radio frame, for example, a subsequent frame, that is
`different than the radio frame within which the first protocol
`allocation control message is located. In one embodiment, the
`first allocation control message is located in the first block.
`The first block may be a first or second protocol block, for
`example, an 802.l6(e) or 802.16(m) block.
`[0046] The sub-blocks may be described based on their
`position in the frame and the characteristics of the sub-block.
`For example, a 5 msec frame supporting both 802.16(e) and
`802.16(m) protocols may be characterized as one of the
`region types discussed above. There are five types of 802.16
`(n1) sub-blocks. Each sub block has a unique characteristic
`designed to achieve the backward compatibility goals and
`efficient 802.l6(m) performance. An 802.16(m) DL Lead
`Sub-Block contains a legacy 802.16(e) pre-amble in the first
`symbol. The remaining symbols of the frame may be allo-
`cated to 80216011). This sub-block may only be transmitted
`in the first sub-frame. An 802.l6(m) DL Lead Compatible
`sub—block also contain a 802.16(e) FCH and 802.16e DL-
`MAP in addition to the l6e pre-amble for backward compat-
`ibility with