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公开(公告)号：CA2298361A1
公开(公告)日：2000-09-11
申请号：CA2298361
申请日：2000-02-11
Applicant: LUCENT TECHNOLOGIES INC
Inventor： LAROIA RAJIV , VANDERVEEN MICHAELA C , LI JUNYI
Abstract: An orthogonal frequency division multiplexing (OFDM) based spread spectrum multiple access system using offsetting between cells, and in particular, the use of tone offsetting and time offsetting, is disclosed. More specifically, frequencies that define the tone set of one cell is offset from the frequencies that define the tone set of at least one adjacent cell. In other words, if a first base station is using tones F1, F2, ..., F N within a frequency band, then a second base station adjacent to the first base station uses tones F1+.DELTA.f, F2+.DELTA.f ..., F N+.DELTA.f within the same frequency band. Furthermore, the symbol timing of the base-station of one cell may be offset from the symbol timing of the base-station of an adjacent cell. Thus, if a first base station starts successive symbols at times T1, T2, and T3, then a second base station adjacent to the first base station starts its respective corresponding successive symbols at times T1+.DELTA.t, T2+.DELTA.t, and T3+.DELTA.t. For example, in a cellular system with hexagonally shaped cells, the tone sets of two adjacent cells are offset by 1/3 of the spacing between adjacent tones, and the symbol timings of two adjacent cells are offset by 1/3 of a symbol period. Advantageously, the intercell interference is more uniformly distributed among users in a cell.
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公开(公告)号：CA2298360A1
公开(公告)日：2000-09-11
申请号：CA2298360
申请日：2000-02-11
Applicant: LUCENT TECHNOLOGIES INC
Inventor： LI JUNYI , LAROIA RAJIV , VANDERVEEN MICHAELA C
Abstract: In an orthogonal frequency division multiplexing (OFDM) based spread spectrum multiple access system the entire bandwidth is divided into orthogonal tones, and all of the orthogonal tones are reused in each cell. To reduce peak-to-average ratio at the mobile transmitter, each voice user is allocated preferably a single one, but no more than a very small number, of the orthogonal tones for use in communicating with the base station. Data users are similarly allocated tones for data communication, however, the number of tones assigned for each particular data user is a function of the data rate for that user. The tone assignment for a given user is not always the same within the available band, but instead the tones assigned to each user are hopped over time. More specifically, in the downlink, the tones assigned to each user are change relatively rapidly, e.g., from symbol to symbol, i.e., the user fast "hops" from one tone to another. However, in the uplink, preferably slow hopping is employed to allow efficient modulation of the uplink signal which necessitates the employing of additional techniques, such as interleaving, to compensate for the reduction in the intercell interference averaging effect. For data communication power control is employed in the uplink and/or downlink so that the transmission rate is increased, e.g., by increasing the number of symbols transmitted per tone per unit time or the coding rate, as a function of allocated power per tone and the corresponding channel attenuation.
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公开(公告)号：CA2258412A1
公开(公告)日：1999-08-03
申请号：CA2258412
申请日：1999-01-12
Applicant: LUCENT TECHNOLOGIES INC
Inventor： KUSTKA GEORGE JOHN , WANG JIN-DER , LAROIA RAJIV , DAGDEVIREN NURI RUHI
Abstract: An Asymmetric Digital Subscriber Loop (ADSL) Discrete Multi-Tone system has disjoint and adjacent upstream and downstream channels. During the training phase of an ADSL connection, an ADSL DMT transmitter first determines a round trip propagation delay by transmitting a ranging signal to a far-end ADSL endpoint. During the subsequent communications phase, the ADSL transmitter synchronizes transmission of DMT symbols to a reference clock. In addition, the cyclic extensions of each DMT symbol are increased as a function of the propagation delay.
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公开(公告)号：BRPI0100361B1
公开(公告)日：2015-12-15
申请号：BR0100361
申请日：2001-02-05
Applicant: LUCENT TECHNOLOGIES INC
Inventor： LI JUNYI , LAROIA RAJIV , UPPALA SATHYADEV VENKATA , RANGAN SUNDEEP
Abstract: método e aparelho de comunicação de link ascendente entre uma estação móvel e uma estação base de um sistema de comunicação sem fio técnicas aperfeiçoadas de sincronização de temporização e de controle de acesso para uso em um sistema sem fio multiplexado de divisão de freqüência ortogonal (ofdm) ou outro tipo de sistema de comunicação sem fio. de acordo com a invenção, um sistema de controle de acesso e de sincronização de link ascendente é provido no qual as estações móveis transmitem certos sinais de temporização e de acesso em intervalos dedicados em uma seqüência de link ascendente. controle de acesso é implementado ilustrativamente como um processo de dois estágios no qual uma estação móvel determinada transmite primeiro um sinal genérico de acesso de link ascendente em um dos intervalos. se esse acesso for aceito, a estação base transmite uma confirmação de acesso contendo correções iniciais de energia e de temporização, junto com atribuições iniciais de canal no qual a estação móvel pode iniciar um processo de estabelecimento de chamada. para re-sincronização, estações móveis transmitem sinais de sincronização de temporização nos intervalos dedicados de temporização e de acesso. a estação base mede o tempo de chegada dos sinais, e envia de volta correções apropriadas de temporização. a invenção dessa forma garante que seja mantida a ortogonalidade entre as estações móveis.
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公开(公告)号：CA2330776C
公开(公告)日：2008-03-18
申请号：CA2330776
申请日：2001-01-12
Applicant: LUCENT TECHNOLOGIES INC
Inventor： LI JUNYI , RANGAN SUNDEEP , LAROIA RAJIV , UPPALA SATHYADEV VENKATA
Abstract: Signal construction, detection and estimation techniques for use in uplink timing synchronization and access control in an orthogonal frequency division multiplexed (OFDM) wireless system or other type of wireless communication system. In accordanc e with an illustrative embodiment of the invention, timing and access signals to be transmitted in designated timing and access intervals are constructed from orthogonal multitone signals. The multitone signals may be similar to multitone signals used in OFDM data transmission, except that a cyclic prefix associated with reception of the signals in a ba se station is extended to cover the timing errors of mobile stations not yet synchronized. The invention also provides design techniques which optimize the time resolvability and pe ak- to-average ratio of the multitone signals, an efficient fast Fourier transform (FFT) based technique for maximum likelihood timing estimation, and a robust linear filtering techniqu e for averaging timing estimates from different synchronizations.
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Patent Agency Ranking
公开(公告)号：CA2327980C
公开(公告)日：2007-02-13
申请号：CA2327980
申请日：2000-12-08
Applicant: LUCENT TECHNOLOGIES INC
Inventor： RANGAN SUNDEEP , UPPALA SATHYADEV VENKATA , LI JUNYI , LAROIA RAJIV
IPC: H04J11/00 , H04B1/7136 , H04B1/7143 , H04L5/02
Abstract: Tone sequences in a frequency hopping arrangement are generated and assign ed by advantageously employing a combination of a sequence generator and a sequence assignor to generate sequences and assign them on a time slot by time slot basis. In a transmitter, the sequence generator and sequence assignor, in combination wi th a user tone assignor are employed to generate and assign tone sequences to a user o n a time slot by time slot basis. In a receiver, the sequence generator and sequence assignor, in combination with a user tone identifier are employed to generate sequences a nd to identify incoming tone sequences to a user on a time slot by time slot basis . Specifically, the sequence assignment in a time slot is such that a prescrib ed plurality of sequences is assigned to a particular user. This partitioning of the tasks facilitates the use of a sequence generator that generates sequences with the desirable properties of interference and frequency diversity and, which, leaves the task of properly assigning these sequences among one or more users to the sequence assignor. The sequen ce assignor functions in such a manner that the interference and frequency diversity properties for the one or more users are preserved, and this is further facilitated by assigning sequences in such a manner that they maximally overlap prior assigned sequences. In one embodiment of the invention, a Latin square based sequence is generated in accordance with a first prescribed process. In a second embodiment of the invention, a Latin cube based sequence is generated in accordance with a second prescribed process. In a third embodiment of the invention, a Latin hypercub e of prescribed dimension based sequence is generated in accordance with a third prescribed process. In still another embodiment of the invention, the principles of the invention are employed to realize frequency band hopping.
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公开(公告)号：CA2258412C
公开(公告)日：2006-12-12
申请号：CA2258412
申请日：1999-01-12
Applicant: LUCENT TECHNOLOGIES INC
Inventor： KUSTKA GEORGE JOHN , LAROIA RAJIV , WANG JIN-DER , DAGDEVIREN NURI RUHI
Abstract: An Asymmetric Digital Subscriber Loop (ADSL) Discrete Multi-Tone system h as disjoint and adjacent upstream and downstream channels. During the training phase of an ADSL connection, an ADSL DMT transmitter first determines a round trip propagation delay by transmitting a ranging signal to a far-end ADSL endpoint. During th e subsequent communications phase, the ADSL transmitter synchronizes transmission of DMT symbols to a reference clock. In addition, the cyclic extensions of each DMT symbol are increased as a function of the propagation delay.
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公开(公告)号：CA2338471C
公开(公告)日：2006-11-07
申请号：CA2338471
申请日：2001-02-27
Applicant: LUCENT TECHNOLOGIES INC
Inventor： VISWANATH PRAMOD , RANGAN SUNDEEP , LI JUNYI , LAROIA RAJIV
IPC: H04B1/713 , H04J11/00 , H04B1/7143 , H04B1/7156 , H04B1/76 , H04B7/26 , H04L5/02 , H04L27/26 , H04Q7/36
Abstract: A base station having the strongest downlink signal is identified by utilizi ng a unique slope of a pilot tone hopping sequence being transmitted by a base station. Specifically, base station identification is realized by determining the slo pe of the strongest received pilot signal, i.e., the received pilot signal having the maximum energy. In an embodiment of the invention, the pilot tone hopping sequence i s based on a Latin Squares sequence. With a Latin Squares based pilot tone hopping sequence, all a mobile user unit needs is to locate the frequency of the pilot tones at on e time because the pilot tone locations at subsequent times can be determined from the slop e of the Latin Squares pilot tone hopping sequence. The slope and initial frequency shift of the pilot tone hopping sequence with the strongest received power is determined by employing a unique maximum energy detector. In one embodiment, the slope and initial frequency shift of the pilot signal having the strongest received power is determined by finding the slope and initial frequency shift of a predicted s et of pilot tone locations having the maximum received energy. In another embodiment, th e frequency shift of the pilot signal with the strongest, i.e., maximum, received power is estimated at each of times "t". These frequency shifts are employed in accordance with a prescribed relationship to determine the unknown slope and the initial frequency shift of the pilot signal.
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公开(公告)号：DE69925178T2
公开(公告)日：2006-02-23
申请号：DE69925178
申请日：1999-01-26
Applicant: LUCENT TECHNOLOGIES INC
Inventor： DAGDEVIREN NURI RUHI , KUSTKA GEORGE JOHN , LAROIA RAJIV , WANG JIN-DER
Abstract: An Asymmetric Digital Subscriber Loop (ADSL) Discrete Multi-Tone system has disjoint and adjacent upstream and downstream channels. During the training phase of an ADSL connection, an ADSL DMT transmitter first determines a round trip propagation delay by transmitting a ranging signal to a far-end ADSL endpoint. During the subsequent communications phase, the ADSL transmitter synchronizes transmission of DMT symbols to a reference clock. In addition, the cyclic extensions of each DMT symbol are increased as a function of the propagation delay.
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100.发明专利
公开(公告)号：AU783584B2
公开(公告)日：2005-11-10
申请号：AU8550301
申请日：2001-10-29
Applicant: LUCENT TECHNOLOGIES INC
Inventor： LAROIA RAJIV , LI JUNYI , UPPALA SATHYADEV VENKATA
Abstract: In a wireless communications system, multicast messages are transported to groups of wireless terminals by employing a common control channel to transmit a multicast paging message indicating that multicast traffic data is to be transmitted to a particular group of wireless terminals. In an embodiment of the invention, the essential information transmitted in the common control channel is the identifier of the group of wireless terminals intended to receive the multicast traffic data and the location of a traffic channel on which the multicast traffic is to be transported in a channel resource which may include a representation of bandwidth and time interval. In accordance with an aspect of the invention, the common control channel is associated with a traffic channel in a prescribed fixed manner. Further, the traffic channel used for the purpose of multicast can be the same traffic channel used for the normal point-to-point transmission of traffic data.
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