Joydeep Acharya

US Patent:

8391876, Mar 5, 2013

Filed:

Aug 19, 2010

Appl. No.:

12/805769

Inventors:

Long Gao - Santa Clara CA, US
Joydeep Acharya - Sunnyvale CA, US

Assignee:

Hitachi, Ltd. - Tokyo

International Classification:

H04W 40/00

US Classification:

455447, 455446, 455450

Abstract:

A central base station for interference management in a distributed antenna system comprises a processor; a memory; and a frequency partition module configured to divide the remote radio heads into clusters and allocate a frequency band to each cluster. Multiple clusters use the same frequency band and groups of clusters are formed. A joint scheduler is configured, for each group, to activate at most two clusters at any given time and deactivate remaining clusters in the group, one of the at most two activated clusters being a serving cluster of the group, and to associate one or more users with the serving cluster in the group. An interference alignment module is configured to apply downlink interference alignment between the at most two activated clusters in each group to align transmit directions of all interferences between the at most two activated clusters.

US Patent:

8451944, May 28, 2013

Filed:

Mar 19, 2010

Appl. No.:

13/377866

Inventors:

Sudhanshu Gaur - Campbell CA, US
Joydeep Acharya - Sunnyvale CA, US

Assignee:

Hitachi, Ltd. - Tokyo

International Classification:

H04K 1/02
H04L 25/03
H04L 25/49

US Classification:

375296, 375299, 375346, 375350

Abstract:

A method for processing user symbols with Tomlinson Harashima precoder (THP) in a base station, of a wireless system having K user terminals (UEs) which communicate with the base station via an uplink channel and corresponding downlink (DL) channel, comprises estimating a DL channel matrix H; determining receiver processing matrix V; computing an effective matrix DL channel H; performing QR decomposition of H; computing THP matrices; calculating scalar weights for the UEs; processing user symbols by the THP having the THP matrices to produce an output of filtered vector symbols for the UEs; directing output of the THP to the channel represented by the DL channel matrix through which communications occur in the wireless system with the UEs; performing additional receiver processing on the transmitted signals at the UEs based on Vfor each of the K UEs; and using the scalar weights on the transmitted signals at the UEs.

US Patent:

8488613, Jul 16, 2013

Filed:

May 5, 2011

Appl. No.:

13/101867

Inventors:

Joydeep Acharya - Sunnyvale CA, US

Assignee:

Hitachi, Ltd. - Tokyo

International Classification:

H04L 12/28
H04J 11/00
H04W 4/00

US Classification:

37039521, 370329, 370203

Abstract:

Systems and methods for scheduling multiple user equipments such as mobiles for transmission in the downlink of a cellular communications system. At each scheduling instant the systems and methods return a set of users who should be scheduled based on the past scheduling history of the users, the current individual link gains of the users to the base station, and how the simultaneous scheduling of multiple users affect each other's performance. Since optimal scheduling for communication systems require high computational complexity, low complexity systems and methods are utilized with a performance that is close to the theoretical optimal solution.

US Patent:

8509831, Aug 13, 2013

Filed:

Sep 27, 2010

Appl. No.:

12/890886

Inventors:

Joydeep Acharya - Sunnyvale CA, US
Long Gao - Santa Clara CA, US

Assignee:

Hitachi, Ltd. - Tokyo

International Classification:

H04B 7/00

US Classification:

455507, 4555621, 455562, 4555757, 455 333, 455446

Abstract:

A distributed antenna system comprises users; remote radio heads which are to be divided into clusters; and a central base station (CBS) including a CBS processor, a CBS memory, a user ordering module, and a user scheduling and cluster formation module. The user ordering module is configured to order the users in decreasing values of proportional fair scheduling metrics to provide a set of ordered users. The user scheduling and cluster formation module is configured to schedule the users according to the order of the users in decreasing values of proportional fair scheduling metrics; and for each user being scheduled according to the order of the users, pick up first N number of remote radio heads, in decreasing order of signal strength to the user being scheduled, which have not been picked up previously, to form a cluster of size N for the user being scheduled.

US Patent:

8553639, Oct 8, 2013

Filed:

Feb 7, 2012

Appl. No.:

13/368264

Inventors:

Joydeep Acharya - Sunnyvale CA, US
Long Gao - Santa Clara CA, US
Sudhanshu Gaur - Santa Clara CA, US

Assignee:

Hitachi, Ltd. - Tokyo

International Classification:

H04W 4/00
H04L 12/26
H04W 72/00
G06F 15/173

US Classification:

370329, 370252, 455450, 709226

Abstract:

Systems and methods are directed to deciding the number of subframes in a frame to use for uplink transmission, with the remaining frames used for downlink transmission for a Base Station (BS) in a Time Division Duplexing Long Term Evolution (TDD-LTE). Systems and methods are based on the number of User Equipment (UEs) that the BS has to serve in the uplink and in the downlink, as well as the uplink (UL) and downlink (DL) traffic loads per user. Systems and methods are directed to allowing a TDD LTE BS to partition the subframes in a frame for its UL and DL traffic.

US Patent:

20100290409, Nov 18, 2010

Filed:

May 15, 2009

Appl. No.:

12/466533

Inventors:

JOYDEEP ACHARYA - Sunnyvale CA, US
SIVARAMA VENKATESAN - Milltown NJ, US
HARISH VISWANATHAN - Morristown NJ, US

International Classification:

H04W 72/12

US Classification:

370329, 375260

Abstract:

The present invention provides a method for use in a wireless communication system that supports orthogonal frequency division multiplexing (OFDM) of transmissions over a plurality of subcarriers. One embodiment of the method includes a network entity that allocates one or more of a plurality of sub-bands for communication with an access terminal. Each of the sub-bands includes one or more of the subcarriers and is associated with a corresponding a pseudo-random sequences. The network entity can also transmit one or more of the plurality of pseudo-random sequences over an air interface. The transmitted pseudo-random sequence indicate the sub-bands that are allocated for communication with the access terminal.

US Patent:

20110171955, Jul 14, 2011

Filed:

Jan 14, 2010

Appl. No.:

12/687405

Inventors:

JOYDEEP ACHARYA - Sunnyvale CA, US

Assignee:

HITACHI, LTD. - Tokyo

International Classification:

H04W 48/20

US Classification:

455434

Abstract:

In the embodiments of the present invention, proposed is a method in which a CoMP enabled UE chooses the BSs to be in its cooperating set and a BS partitions its bandwidth to serve its own UEs and UEs from other cells that have requested it to be in its cooperating set.

US Patent:

20130089034, Apr 11, 2013

Filed:

Oct 5, 2011

Appl. No.:

13/253907

Inventors:

Joydeep ACHARYA - Sunnyvale CA, US
Sudhanshu GAUR - Santa Clara CA, US
Long GAO - Santa Clara CA, US

Assignee:

HITACHI, LTD. - Tokyo

International Classification:

H04W 72/04

US Classification:

370329

Abstract:

In a cellular system a user equipment (UE) can associate with different base stations (BS) for its uplink (UL) and downlink (DL) communications. To achieve this, the two BS have to communicate with each other. Systems and methods described herein provide a signaling methodology within a cellular standards framework (such as LTE), by which a UE can associate with different BS for UL and DL communications and further facilitate communication between a BS handling UL and a BS handling DL.