Source: http://www.google.com/patents/US20090185632?ie=ISO-8859-1&dq=6437692
Timestamp: 2014-07-25 03:55:08
Document Index: 57119922

Matched Legal Cases: ['Application No. 60', 'Application No. 60', 'Application No. 61', 'Application No. 61', 'Application No. 61', 'Application No. 61']

Patent US20090185632 - Flexible ofdm/ofdma frame structure for communication systems - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA flexible OFDM/OFDMA frame structure technology for communication systems is disclosed. The OFDM frame structure technology comprises a configurable-length frame which contains a variable length subframe structure to effectively utilize OFDM bandwidth. Furthermore, the frame structure facilitates spectrum...http://www.google.com/patents/US20090185632?utm_source=gb-gplus-sharePatent US20090185632 - Flexible ofdm/ofdma frame structure for communication systemsAdvanced Patent SearchPublication numberUS20090185632 A1Publication typeApplicationApplication numberUS 12/267,502Publication dateJul 23, 2009Filing dateNov 7, 2008Priority dateNov 9, 2007Also published asCN101904125A, EP2215756A2, EP2456116A2, EP2456116A3, US8204025, US20110096783, US20110103406, WO2009062115A2, WO2009062115A3Publication number12267502, 267502, US 2009/0185632 A1, US 2009/185632 A1, US 20090185632 A1, US 20090185632A1, US 2009185632 A1, US 2009185632A1, US-A1-20090185632, US-A1-2009185632, US2009/0185632A1, US2009/185632A1, US20090185632 A1, US20090185632A1, US2009185632 A1, US2009185632A1InventorsSean Cai, Jerry Chow, Hongyun Qu, Huiying FangOriginal AssigneeSean Cai, Jerry Chow, Hongyun Qu, Huiying FangExport CitationBiBTeX, EndNote, RefManReferenced by (39), Classifications (10), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetFlexible ofdm/ofdma frame structure for communication systemsUS 20090185632 A1Abstract A flexible OFDM/OFDMA frame structure technology for communication systems is disclosed. The OFDM frame structure technology comprises a configurable-length frame which contains a variable length subframe structure to effectively utilize OFDM bandwidth. Furthermore, the frame structure facilitates spectrum sharing between multiple communication systems.
generating a frame comprising one or more subframes, each subframe comprising one or more unit subframes, each unit subframe comprising a fixed length duration Tu-sub, and generating a frame synchronization signal and a frame control signal for controlling the subframes in the frame. 2. The method of claim 1, further comprising generating directionality information for each subframe in the frame.
generating one or more frame partitions in the frame, each frame partition comprising one or more subframes, and generating a frame partition control signal for each frame partition comprising for controlling the subframes in the frame partition. 17. The method of claim of 16, wherein the frame control signal comprises the number of frame partitions in the frame.
transmitting a first frame by the first communication system, the first frame comprising one or more subframes, each subframe comprising one or more unit subframes, each unit subframe comprising a fixed length duration Tu-sub, wherein the first frame comprises directionality information for each subframe that indicates whether the subframe is used for downlink transmission, uplink transmission, or reserved, transmitting a second frame by the second communication system, the second frame comprising one or more subframes, wherein the second frame occupies the time durations of the reserved subframes in the first frame. 35. The method of claim 34, wherein the first frame comprises a frame synchronization signal and a frame control signal in a downlink subframe located at the beginning of the first frame.
transmitting a first frame by the first communication system, the first frame comprising one or more subframes, each subframe comprising one or more unit subframes, each unit subframe comprising a fixed length duration Tu-sub, wherein the first frame comprises directionality information for each subframe that indicates whether regions of frequency-time resources of the subframe are used for downlink transmission, uplink transmission, or reserved; transmitting a second frame by the second communication system, the second frame comprising one or more subframes, wherein the second frame occupies the reserved regions of frequency-time resources of the subframes in the first frame. 67. A method of frame control in a communication system, the method comprising:
transmitting a first frame on a first carrier, the first frame comprising one or more frame partitions, each frame partition comprising one or more subframes, each subframe comprising one or more unit subframes, each unit subframe comprising a fixed length duration Tu-sub, transmitting a second frame on a second carrier, the second frame comprising one or more frame partitions, each frame partition comprising one or more subframes, wherein each frame partition in the first frame has a corresponding frame partition in the second frame. 68. The method of claim of 67, wherein the first frame comprises a frame synchronization signal and a frame control signal in a downlink subframe located at the beginning of the first frame.
setting up a first carrier with a first center frequency and a first channel bandwidth; setting up a second carrier with a second center frequency and a second channel bandwidth, wherein the first carrier and the second carrier have a same subcarrier spacing, the first channel bandwidth is adjacent to the second channel bandwidth, the first center frequency and the second center frequency is separated by an integer number of a frequency step, and the frequency step is an integer number of the subcarrier spacing. 91. The method of claim 90, further comprising transmitting signals on subcarriers of the first carrier without causing substantial interference to subcarriers in the second carrier.
RELATED PATENT APPLICATIONS This application claims benefit of priority under 35 U.S.C. � 119(e) to Provisional Application No. 60/986,809, entitled �Flexible OFDM/OFDMA Frame Structure For Communication Systems�, filed Nov. 9, 2007; Provisional Application No. 60/987,747, entitled �Flexible OFDM/OFDMA Frame Structure For Communication Systems�, filed Nov. 13, 2007; Provisional Application No. 61/020,690, entitled �Flexible OFDM/OFDMA Frame Structure For Communication Systems�, filed Jan. 11, 2008; Provisional Application No. 61/021,442, entitled �Flexible OFDM/OFDMA Frame Structure For Communication Systems�, filed Jan. 16, 2008; Provisional Application No. 61/031,658, entitled �Flexible OFDM/OFDMA Frame Structure For Communication Systems�, filed Feb. 26, 2008; and Provisional Application No. 61/038,030, entitled �OFDM/OFDMA Frame Structure For Communication Systems�, filed Mar. 19, 2008, all of which are incorporated by reference herein in their entirety.
FIELD OF THE INVENTION The present invention relates generally to digital communications and more particularly to Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) systems.
BACKGROUND OF THE INVENTION There is an increasing need for mobile high-speed communication systems to provide a variety of services such as downloading music files, TV, Internet, and photo sharing. A mobile high-speed communication system must overcome many difficult operating conditions. Among the many conditions the system must contend with are interference, multipath signals, changing obstructions to the signal line-of-site, Doppler shift, inter-symbol interference (ISI), and changing distances between transmitter and receiver. Orthogonal Frequency Division Multiplexing (OFDM) is one technique developed for high-speed communications that can mitigate many of these difficult conditions.
In particular, the 802.16e amendment to the IEEE 802.16 standard, which is referred to as �802.16e� or simply as �16e� herein, has defined a relatively rigid frame structure in accordance with the WirelessMAN-OFDMA Reference System. A new amendment to the IEEE 802.16 standard, the 802.16m amendment, which is referred to as �802.16m� or simply as �16m� herein, has been proposed. Requirements for the development of the 802.16m as specified by IEEE 802.16m System Requirements Document (IEEE 802.16m SRD), IEEE 802.16m-07/002r4, Oct. 19, 2007, which is incorporated by reference herein in its entirety, stipulate many improvements in performance over the 802.16e WirelessMAN-OFDMA Reference System and operation in many different deployment environments. Improvements in performance include reductions in latency across the air interface, increases in user and sector throughput, and reductions in system overhead. Operation is also required in the presence of varying levels of mobility, from stationary up to 350 km/h and beyond, and in sectors and cells with drastically different coverage ranges, from micro-cells and even femto-cells with coverage ranges in the 10's to 100's meters to large rural macro-cells with coverage ranges greater than 5 kilometers.
SUMMARY OF THE INVENTION A flexible OFDM/OFDMA frame structure for communication systems is disclosed. The OFDM frame structure comprises a configurable-length frame which contains a variable length subframe structure to effectively utilize OFDM bandwidth. Furthermore, the frame structure facilitates spectrum sharing between multiple wireless communication systems.
BRIEF DESCRIPTION OF THE DRAWINGS The present invention, in accordance with one or more various embodiments, is described in detail with reference to the following Figures. The drawings are provided for purposes of illustration only and merely depict exemplary embodiments of the invention. These drawings are provided to facilitate the reader's understanding of the invention and should not be considered limiting of the breadth, scope, or applicability of the invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS In the following description of exemplary embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration of specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the preferred embodiments of the invention.
A subframe is defined as a contiguous number of time units of radio resources within a frame that has the same direction property�i.e., either downlink or uplink. Therefore, a subframe is characterized by two parameters: 1) a direction (downlink or uplink) and 2) a length or duration. This definition essentially retains the definition of subframe from the WirelessMAN-OFDMA Reference System except that there may be two consecutive subframes that possess the same directionality (e.g. downlink subframe followed by another downlink subframe) if the subframes belong to different frame partitions.
T offset - sub  [ n ] = ∑ i = 1 n - 1  T sub  [ i ] . The subframe directionality 202 can take on one of two values (i.e., downlink or uplink) and thus, can be represented by 1 bit of control information per subframe. This subframe direction control bit may be grouped together with the other attributes of each subframe or may be organized as a vector of subframe direction control bits indexed in the order of subframe starting from the 1st subframe at the beginning of the frame. These are examples of ways of organizing the subframe direction control information within a frame; other ways are possible. In order to reduce control signaling overhead at the expense of frame structure flexibility, the applicable frame structure may be selectable from a set of predefined settings in which the positions, lengths and directionalities of subframes within a frame would not need to be individually signaled.
T offset - sub  [ n ] = ∑ i = 1 n - 1  T sub  [ i ] . The subframe directionality 314 can take on one of two values (i.e., downlink or uplink) and thus, can be represented by 1 bit of control information per subframe. This subframe direction control bit may be grouped together with the other attributes of each subframe or may be organized as a vector of subframe direction control bits indexed in the order of subframe starting from the 1st subframe at the beginning of the Frame Partition. These are examples of ways of organizing the subframe direction control information within a Frame Partition; other ways are possible.
As shown in FIG. 5, this method utilizes the concept of physical resource allocation based on a rectangular area within the two-dimensional OFDMA signal�the two dimensions being time and frequency. Such a physical resource allocation is often known as an OFDMA region.
Also in the exemplary method of FDD support of FIG. 8, the parameter Tf,offset 821 should be designed to be configurable on a per-secondary-carrier basis so that the value of the parameter can be set appropriately depending on whether only full FDD MSs are supported or half-duplex FDD (H-FDD) MSs need to be supported also. H-FDD MSs do not transmit and receive at the same time. In the H-FDD case, sufficient delay must be introduced by Tf,offset to allow sufficient non-overlap of the associated Frame Partitions between the primary carrier 800 and the secondary carrier 801 so that downlink and uplink transmissions of sufficient sizes can be performed to an H-FDD MS. For example, the Frame Partitions may be set equal in size and the delay Tf,offset may be set to the size of the Frame Partition to essentially provide an alternating pattern for a particular Frame Partition between the primary and secondary carriers. If only full FDD MSs are supported on a particular BS, the value of Tf,offset may be set substantially shorter since the MS can receive on the primary carrier 800 and transmit on the secondary carrier 801 simultaneously; in this case, time need only be allotted for the MS to receive and process the Frame Partition control information 814 for the secondary carrier. A shorter value of Tf,offset allows faster exchanges of data between a BS and MS, which is especially relevant for control signaling exchanges�this can improve performance of certain operations that benefit substantially from fast signaling exchanges, such as Hybrid Automatic Repeat Request (HARQ) operation.
FIG. 9 illustrates legacy 16e support in a 16m frame structure according to an embodiment of the invention. According to this embodiment of the invention, the 16m frame structure 900 retains many of the attributes of the flexible frame depicted in FIG. 1. In addition, as shown in FIG. 9, certain NULL subframes 904 in the 16m frame are reserved for legacy 16e use. There are no 16m transmissions in the time durations of those �NULL� subframes 904. These time durations are reserved for use by subframes 910, 911, 912 and 913 of the legacy 16e frame.
Option 2: Take one of the legacy sets of numerology (for example, the popular 5/10 MHz). The MS will still need to support different sets of numerology for legacy support�namely 7/14 MHz and 8.75 MHz. The argument of sharing only one set of numerology between 16m and 16e design will no longer be true. At least we cannot have one set of numerology for 16m design for global roaming. Since a 16m MS design would need to support multiple sampling base frequencies for legacy support anyway, such as providing support for both 16m (2.5 GHz, 10.9375 kHz) and 16e (3.5 GHz, 7.8125 kHz) using a rate change filter with one crystal or via separate crystals, then there is no difference in design complexity regardless of the subcarrier spacing used by 16m�either 10.9375 kHz or other subcarrier spacing such as 12.5 kHz. However, as discussed below, there are many issues with using the 10.9375 kHz subcarrier spacing.
Problem No. 2 is that legacy numerology has low spectral efficiency due to unused guard subcarriers. The numerology based on a typical legacy 16e design can be found in Table 310 a of IEEE 802.15e 2005. Out of 914 subcarriers that fall into the 10 MHz bandwidth, there are only 840 subcarriers that can be used to transmit information�8.8% of the bandwidth is wasted. Furthermore, the bandwidth occupied by the 914 subcarriers does not fully fill the 10-Mhz carrier bandwidth. The following is the formula on how to calculate the maximum frequency efficiency:
n Efficiency = R Modulation � n UsedSubcarriers T symobol � BW System ( Eq .  2  -  1 ) where RModulation is modulation rate (e.g., 4 for 16QAM), nUsedSubcarriers is number of used subcarriers within the nominal system bandwidth, Tsymobol is symbol period, and BWsystem is the nominal system bandwidth.
T symobol = 1 f Δ ( Eq .  2  -  2 ) where fΔ is subcarrier spacing.
BW system ≧n MaximumSubcarriers �f Δ (Eq. 2-3)
n Efficiency ≤ R Modulation � n UsedSubcarriers n MaximumSubcarriers ( Eq .  2  -  4 ) The frequency efficiency is proportional to the number of used subcarriers number over the maximum number of subcarriers within the system bandwidth. We can see if we can use the 73 Guard Subcarriers (nMaximumSubcarriers−nUsedSubcarriers=914−841=73) and 1 DC subcarrier to transmit data and divided it by the maximum number of subcarriers of 914, the new 16m system can be immediately 8.8% more efficient. The proposed 16m numerology described in one embodiment of the invention allows all subcarriers to be used for data transmission without Guard Subcarriers since the subcarrier spacings between adjacent abutting carriers are aligned. This makes operation with the proposed 16m numerology to be 8.8% more efficient by design when compared to PUSC operation with the existing 16e numerology. When the operator bandwidth has sufficient guard band around a carrier, then the 8.8% would not be wasted.
Also shown in FIG. 14 is the issue with using the legacy subcarrier spacing of 10.9375 kHz for the 5 and 10-MHz bandwidths in this scenario�since there is not an integer number of subcarriers from the carrier center frequency to the carrier edge, the subcarriers are not aligned between the adjacent carriers. The nature of OFDM operation is such that transmissions on a subcarrier do not introduce interference power at points that are an integer number of subcarrier spacings from the transmitting subcarrier but do cause interference power between these points. Therefore, subcarriers not being aligned between adjacent carriers means that interference from transmissions near the edge of one carrier causes excessive interference to subcarriers near the edge of the adjacent carrier if not properly addressed. In the design of the legacy WirelessOFDMA-MAN Reference System, this issue was addressed via the combination of two approaches: 1) the reservation of a number of subcarriers at the carrier edge as unused guard subcarriers so that some interference reduction is achieved by natural decay of the transmitted signal power with increasing frequency separation, and 2) the use of a transmit filter to further reduce the interference power to the adjacent carrier to an acceptable level. Both of these approaches incur overhead: 1) loss of capacity of between 5% to more than 8% due to guard subcarriers, and 2) implementation cost/complexity due to requirement of transmit filter. Both of these overheads of the legacy system can be eliminated by simply aligning the subcarriers between the adjacent carriers.
Problem No. 4 is that legacy numerology lacks multi-carrier scalability for multi-carrier deployment. Service providers often prefer scalable deployment plan in which more carriers are launched as the business grows. The incompatible subcarrier spacing unnecessarily restricts the efficiency and flexibility for 1.25 MHz series (5, 8.75, 10, 20 MHz) and 3.5 MHz series (3.5, 7, 14 MHz) to work in multi-carrier mode, with the carriers being of the same or a mixture of different system bandwidths. FIG. 15 illustrates an exemplary operation of multi-carrier deployment with guard bands. FIG. 16 illustrates an exemplary operation of mixed system bandwidths multi-carrier deployment. If the carriers are operated as adjacent carriers as illustrated in FIGS. 15 and 16, inter-carrier interference due to incompatible subcarrier spacings necessitates the presence of guard subcarriers as was discussed above. In addition, the multiple carriers cannot be operated as an overlay of several multiple bandwidths onto a common aggregate bandwidth (common FFT) in order to support devices of different bandwidth capabilities at the same time�this feature is important for supporting devices with very different cost, complexity and throughput requirements on a common air interface (e.g., from low-rate, low-cost remote data collection/monitoring devices to high-end multimedia devices). This multi-carrier mode is illustrated in FIG. 17, which illustrates an exemplary operation of mixed bandwidths multi-Carrier deployment without guard bands.
There are issues with approach (a) described above. Legacy support is adversely affected since the centering of carriers for 802.16m will be different from that for the WirelessOFDMA-MAN Reference System. This mis-alignment of carriers is illustrated in FIG. 18. An important characteristic to note from FIG. 18 is that the offsets between the two sets of carriers are not constant, which complicates the design and engineering of legacy support significantly. The offset in center frequencies resulting from the different rasters causes mis-alignment of the operating carrier bandwidth and of the subcarriers between the legacy zones and the new 16m zones when they occupy overlapping frequency spaces�an example of which is illustrated in FIG. 18. Having a separate set of carrier center frequencies for 802.16m operation due to a different raster also adversely affects the time required for 802.16m MSs to search for available 16m or legacy service due to a doubling of the number of possible center frequencies that need to be searched.
Implementations are affected since a consistent centering of a carrier or a set of adjacent carriers within the same relative position within a spectrum band or block within a band cannot be defined�this may impact the availability of low-cost generic parts in designs.
Problem No. 9 is that a new 16m frame design based on legacy numerology is not backward compatible with LTE frame structure in time. Due to the unequal symbol durations caused by multiple sets of existing legacy numerology, a 16m frame structure based on substructure boundaries that are aligned to symbols of the legacy numerology is unsuitable. Therefore the 16m unit subframe design (or equivalent term of �slot�) can not be aligned with the current LTE design. It can not be backward compatible with LTE Super-frame in time.
FIG. 19 illustrates a 16m system having a subcarrier spacing of 12.5 kHz. As shown in FIG. 19, the 12.5 kHz subcarrier spacing is applied for all the channel bandwidth, e.g., 5/10/20 MHz, 3.5/7/14 MHz and also 8.75 MHz. The 12.5 kHz subcarrier spacing has a property of good trade-off of mobility and frequency efficiency with CP overhead, and divides evenly into the 250-kHz channel raster. The sampling frequency of different channel bandwidths will be based on this subcarrier spacing and appropriate FFT size. It means that all the channel bandwidths will have the same base sampling frequency. The mobile stations can roam to different carrier bandwidths in different frequency bands while utilizing the same OFDMA parameter set�this feature is very crucial for a simplified coherent 4G standard and developing a healthy ecosystem.
Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7953050 *Dec 30, 2010May 31, 2011Huawei Technologies Co., Ltd.Relay transmission method and apparatusUS7953051 *Jan 31, 2011May 31, 2011Huawei Technologies Co., Ltd.Relay transmission method and apparatusUS7961688 *Jan 31, 2011Jun 14, 2011Huawei Technologies Co., Ltd.Relay transmission method and apparatusUS7961689Sep 11, 2008Jun 14, 2011Adc Telecommunications, Inc.Method and apparatus for determining an end of a subframe in a TDD systemUS8036145 *Apr 28, 2009Oct 11, 2011Fujitsu LimitedFrame structure for a wireless communication systemUS8139537 *Nov 5, 2008Mar 20, 2012Wi-Lan, Inc.Advanced technology frame structure with backward compatibilityUS8326309 *Mar 6, 2009Dec 4, 2012Bae Systems Information And Electronic Systems Integration Inc.Resource allocation in co-existence modeUS8385373 *Jun 24, 2008Feb 26, 2013Adc Telecommunications, Inc.Method and apparatus for frame detection in a communications systemUS8542639 *Jan 2, 2009Sep 24, 2013Lg Electronics Inc.Frame for flexibly supporting heterogeneous modes and TDD/FDD modes, and method for transmitting signals using the sameUS8547989 *Apr 28, 2009Oct 1, 2013Qualcomm IncorporatedMethods and systems for LTE-WIMAX coexistenceUS8553593 *Jun 17, 2010Oct 8, 2013Lg Electronics Inc.Apparatus and method for performing communication using frame structure supporting H-FDD operationUS8553632 *Mar 17, 2009Oct 8, 2013Ntt Docomo, Inc.Base station apparatus, user apparatus, and method used in mobile communication systemUS8619724 *May 16, 2011Dec 31, 2013Huawei Technologies Co., Ltd.Relay transmission method and apparatusUS8638652 *May 28, 2010Jan 28, 2014Zte (Usa) Inc.Signal transmission with fixed subcarrier spacing within OFDMA communication systemsUS8675537Apr 2, 2009Mar 18, 2014Qualcomm IncorporatedMethod and apparatus for using MBSFN subframes to send unicast informationUS8687585Feb 13, 2012Apr 1, 2014Wi-Lan, Inc.Advanced technology frame structure with backward compatibilityUS8699385 *Jan 6, 2010Apr 15, 2014Lg Electronics Inc.Method for transmitting and receiving signals using a time division duplexing frame structureUS8711773 *Sep 2, 2010Apr 29, 2014Blackberry LimitedMulti-carrier operation for wireless systemsUS8711781Sep 14, 2012Apr 29, 2014Blackberry LimitedMulti-carrier operation for wireless systemsUS8761032Jun 27, 2008Jun 24, 2014Qualcomm IncorporatedRandom reuse based control channelsUS8761151Sep 2, 2009Jun 24, 2014Blackberry LimitedUplink control signal design for wireless systemUS20090116427 *Nov 5, 2008May 7, 2009Nextwave Broadband Inc.Advanced technology frame structure with backward compatibilityUS20090219875 *Jan 2, 2009Sep 3, 2009Lg Electronics Inc.Frame for flexibly supporting heterogeneous modes and tdd/fdd modes, and method for transmitting signals using the sameUS20090257388 *Apr 6, 2009Oct 15, 2009Qualcomm IncorporatedSystems and methods to define control channels using reserved resource blocksUS20100128690 *Nov 25, 2009May 27, 2010Futurewei Technologies, Inc.Method and Apparatus for Partitioning a Resource in a Wireless Communication SystemUS20100135235 *Nov 25, 2009Jun 3, 2010Qualcomm IncorporatedBlank subframe uplink designUS20100135272 *Apr 28, 2009Jun 3, 2010Qualcomm IncorporatedMethods and systems for lte-wimax coexistenceUS20110013543 *Jun 17, 2010Jan 20, 2011Lg Electronics, Inc.Apparatus and method for performing communication using frame structure supporting h-fdd operationUS20110032850 *May 28, 2010Feb 10, 2011Sean CaiSignal transmission with fixed subcarrier spacing within ofdma communication systemsUS20110051634 *Aug 25, 2010Mar 3, 2011Lg Electronics Inc.Method of transmitting and receiving control information in a wireless communication systemUS20110075750 *Mar 17, 2009Mar 31, 2011Ntt Docomo, Inc.Base station apparatus, user apparatus, and method used in mobile communication systemUS20110158196 *Mar 11, 2011Jun 30, 2011Fujitsu LimitedFrame structure for a wireless communication systemUS20110216675 *May 16, 2011Sep 8, 2011Huawei Technologies Co., Ltd.Relay Transmission Method and ApparatusUS20110256836 *Oct 29, 2009Oct 20, 2011Ntt Docomo, Inc.Radio base station apparatus and mobile terminal apparatusUS20120002575 *Jan 6, 2010Jan 5, 2012Min Seok Nohmethod and device for transmitting and receiving a signal using a time division duplexing frame structure in a wireless communication systemUS20120057524 *Sep 2, 2010Mar 8, 2012Dong-Sheng YuMulti-carrier operation for wireless systemsUS20120287837 *Jan 12, 2011Nov 15, 2012Jeongki KimApparatus and method for performing carrier switching operation for e-mbs service in multicarrier systemWO2011108846A2 *Mar 2, 2011Sep 9, 2011Lg Electronics Inc.Multicarrier based communication method and deviceWO2011147167A1 *Nov 18, 2010Dec 1, 2011Zte CorporationMessage transmission method, base station, terminal and multi-standard communication system* Cited by examinerClassifications U.S. Classification375/260International ClassificationH04K1/10Cooperative ClassificationH04L5/0044, H04L5/0091, H04L5/1469, H04L5/0053, H04L5/0007, H04L5/0048European ClassificationH04L5/00C4, H04L5/14TLegal EventsDateCodeEventDescriptionApr 2, 2009ASAssignmentOwner name: ZTE (USA) INC., CALIFORNIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CAI, SEAN;CHOW, JERRY;QU, HONGYUN;AND OTHERS;REEL/FRAME:022509/0065;SIGNING DATES FROM 20090122 TO 20090306Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CAI, SEAN;CHOW, JERRY;QU, HONGYUN;AND OTHERS;SIGNING DATES FROM 20090122 TO 20090306;REEL/FRAME:022509/0065RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google