Per-user unitary rate control: Difference between revisions

Revision as of 05:02, 31 January 2012

Latest revision as of 05:33, 3 February 2022

(38 intermediate revisions by 25 users not shown)

Line 1:

{{multiple issues|

{{multiple issues|COI=December 2011|POV=December 2011|lead too short=December 2011|technical=December 2011|very long=December 2011|refimprove = December 2011|wikify = January 2012}}

{{NOTCOI|date=DecemberMarch 20112018}}

{{close paraphrasingnotability|date=DecemberMarch 20112018}}

{{more footnotes|date=December 2021}}

{{citation style|date=July 2019}}}}

{{Use dmy dates|date=October 2017}}

'''Per-user unitary rate control''' ('''PU²RC''') is a multi-user [[MIMO]] (multiple-input and multiple-output) scheme. PU²RC uses both transmission pre-coding and multi-user scheduling. By doing that, the network capacity is further enhanced than the capacity of the single-user MIMO scheme.

;* Background technologies: A single-user MIMO was initially developed to improve the spectral efficiency of point-to-point wireless transmission link. A multi-user MIMO was developed for cellular systems where the base station simultaneously communicates with multiple users.

Per-User Unitary Rate Control (PU²RC) is the advanced multi-user [[MIMO]] technique which utilizes the concept of both pre-coding matrices and scheduling to enhance the system performance of multiple antenna wireless networks.

;* Principle: The concept of Per-User Unitary Rate Control (PU²RC) was proposed in [http://www.google.com/patents/about?id=lpWnAAAAEBAJ&dq=7,324,480 US Patent No. 7,324,480, ''Mobile communication apparatus and method including base station and mobile station having multi-antenna''] by James S. Kim, Kwang Bok Lee, Kiho Kim and Changsoon Park.

;Background technologies: A single-user MIMO was initially developed to improve the spectral efficiency of point-to-point wireless transmission link. A multi-user MIMO was developed for cellular systems where the base station simultaneously communicates with multiple users.

;Principle: The concept of Per-User Unitary Rate Control (PU²RC) was proposed in [http://www.google.com/patents/about?id=lpWnAAAAEBAJ&dq=7,324,480 US Patent No. 7,324,480, ''Mobile communication apparatus and method including base station and mobile station having multi-antenna''] by James S. Kim, Kwang Bok Lee, Kiho Kim and Changsoon Park.

Recently, PU²RC has been adopted in the IEEE 802.16m system description documentation (SDD) and the concept of this scheme was included in 3GPP [[3GPP Long Term Evolution|LTE]] standard.

==Technology==

Per-user unitary rate control (PU²RC) is a practical multi-user [[MIMO]] solution. PU²RC allows a base station to transmit different data streams to multiple users simultaneously. The base station selects target users from candidate users based on the information fed by users. Transmission data are multiplied by a pre-coding matrix selected from the set of predefined matrices before transmission. The selection of a pre-coding matrix is determined based on the information provided by users. The selection of both target users and a pre-coding matrix according to the information provided by mobiles enables the utilization of multi-user diversity and data multiplexing at the same time. Moreover, using predefined precoding matrices reduces feedback overhead from users to the base station. Pre-coding matrices used in this scheme is unitary. The use of unitary pre-coding matrices facilitates the estimation of interference from other users' data to the unintended user.

Per-User Unitary Rate Control (PU²RC) is the first practical multi-user MIMO scheme. In this scheme different data may simultaneously be transmitted to multiple users from the base station.

Users to be served are selected from the set of service-requesting users by the base station using the information provided by users.

Data transmitted to mobile users are multiplied by a pre-coding matrix selected from the set of predefined matrices before transmission. The selection of a pre-coding matrix is made based on the information provided by users.

The selection of users and a pre-coding matrix using the information provided by mobiles enables the utilization of multi-user diversity and reduces feedback overhead from users to the base station.

Pre-coding matrices used in this scheme is unitary. The use of unitary pre-coding matrices facilitates the estimation of interference from other users’ data to the unintended user.

==Mathematical description==

The operation isof describedPU²RC is mathematically belowdescribed for the transmitter and receiver sidesides, respectively.

[[Image:Pu2rc over single user.png|thumb|400px|right|Throughput performance of PU²RC over the single-user & no scheduling scheme]]

The operation is described mathematically below for the transmitter and receiver side.

===Base station===

The transmitter antenna array has <math>N_t</math> elements. The transmit signal vector is modeled as follows:

It is assumed that the base station employs <math>N_t</math> transmission antennas. The <math>N_t \times 1</math> transmission signal vector is given by

:<math> \mathbf{x} = \sum_{i=1}^K \mathbf{w}_i P_i s_i</math>

where :<math>\mathbf{x}</math> is= the <math>N_t\sum_{i=1}^K \timesmathbf{w}_i 1P_i s_i</math> vector of transmitted symbols and
where <math>\mathbf{w}_i</math> is the <math>N_t \times 1</math> linear precoding vector. PU²RC generates <math>{\mathbf{w}_i}</math> based on the received finite channel status information, which is delivered to the base station byfrom the user equipment (UE) usingthrough auplink codedfeedback signaling. The feedback signal consists of index in a look-up table indexof a precoding codebook.

===Receiver side===

Every receiver has a receive antenna array with <math>N_r</math> elements. The receive signal vector at user <math>k (=1,2,\ldots,K)</math> is modeled as follows:

:<math>\mathbf{y}_k = \mathbf{H}_k\mathbf{x}+\mathbf{n}_k</math>

where <math>\mathbf{y}_k</math> and <math>\mathbf{n}_k</math> are the <math>N_r \times 1</math> received symbol and noise, respectively, and <math>\mathbf{H}_k</math> is the <math>N_r \times N_t</math> matrix with the channel coefficients.

===Throughput performance===

The figure illustrates the throughput advantage of PU²RC over the conventional single-user and no scheduling scheme, assuming that the codebook size is one, i.e., <math>(G=1)</math>. For larger codebook sizes the performance can be better than the performance of the unit-size codebook. Because of codebook-based multi-user scheduling, PU²RC outperforms the conventional single-user and no scheduling scheme when the number of users is larger than one. Note that the performance plotted in the figure for the two systems were obtained assuming linear receiver.

==See also==

==PU²RC Source and Background Materials==

* [[Multiple-input multiple-output communications]]

* [[Multi-user MIMO]] as the advanced MIMO communication technology

* [[Precoding]]

* [[Spatial multiplexing]]

==References==

* James S. Kim, K. B. Lee, et al., Mobile communication apparatus and method including base station and mobile station having multi-antenna, US PTO 7,324,480

* [http://mobile.snu.ac.kr/mcl_list/papers/journal/IEICEtcomm_200608_sjkim_hjkim_cspark_kblee.pdf S. J. Kim, H. J. Kim, C. S. Park, and K. B. Lee, "On the Performance of Multiuser MIMO Systems in WCDMA/HSDPA: Beamforming, Feedback and User Diversity," IEICE Transactions on Communications, vol. E98-B, no. 8, pp. 2161–2169, Aug. 2006.]

* 3GPP TSG RAN WG1#31 R1-030354, [http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_31/docs/Zips/R1-030354.zip Per unitary basis stream user and rate Control (PU2RC)], 3GPP TSG-R1-030354, Tokyo, Fed 18-2118–21, 2003. (See also R1-030130)

#* Samsung, SNU, [http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_44/Docs/R1-060335.zip 3GPP"Downlink MIMO for EUTRA," in 3GPP TSG RAN WG1 # 44/R1-060335 “Downlink MIMO for EUTRA,” Samsung and SNU]

* Kim, J.S., Hojin Kim, Yongxing Zhou, Jianjun Li, ``Multi-Mode Multi-User MIMO System with Finite Rate Feedback'', IEEE Wireless Communication Systems, 2006. ISWCS '06. 3rd International Symposium on, 6-8 Sept. 2006

* [http://mobile.snu.ac.kr/mcl_list/papers/conference/ew200504_sjkim_hjkim_kblee.pdf Multiuser MIMO Scheme for Enhanced 3GPP HSDPA]

* Kim, J.S., Hojin Kim, Yongxing Zhou, Jianjun Li, `'`Multi-Mode Multi-User MIMO System with Finite Rate Feedback'', IEEE Wireless Communication Systems, 2006. ISWCS '06. 3rd International Symposium on, 6-86–8 Sept.Sep 2006''

* R. W. Heath, Jr., M. Airy, and A. J. Paulraj, "Multiuser Diversity for MIMO Wireless Systems with Linear Receivers," Proc. of the IEEE Asilomar Conf. on Signals, Systems, and Computers, pp.&nbsp;1194 –1199, vol.2, Pacific Grove, California, 4–7 Nov 2001.

* A. Kogiantis and L. Ozarow, "Downlink best-effort packet data with multiple antennas," ICC'03, Volume 1, 11–15 May 2003 Page(s):715 – 719.

* K.K. Wong, R.D. Murch and K.B. Letaief, "Performance Enhancement of Multiuser MIMO Wireless Communication Systems," IEEE Transactions on Communications, Vol 50 No 12, Dec. 2002, pp 1960 –1970

* Further benefits of the revised definition of CQI for TxAA, 3GPP TSG-R1-030130, San Diego, 7–10 Jan. 2003.

==Further reading==

== MU-MIMO Standard Contributions ==

* [http://www.eurecom.fr/~gesbert/papers/TutorialMUMIMOv3.pdf D. Gesbert, M. Kountouris, R W. Heath Jr., C. B. Chae, T. Sälzer, From Single User to Multiuser Communications: Shifting the MIMO Paradigm]

# [http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_31/docs/Zips/R1-030354.zip 3GPP TSG RAN WG1#31, R1-030354, Per unitary basis stream user and rate Control (PU2RC), 3GPP TSG-R1-030354, Tokyo, Fed 18-21, 2003. (See also R1-030130)]

* [http://www.ll.mit.edu/asap/asap_04/DAY1/14_PR_POOR.PDF V. Poor, Multiuser MIMO Systems]

# [http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_44/Docs/R1-060335.zip 3GPP, TSG RAN WG1#44/R1-060335 “Downlink MIMO for EUTRA,” Samsung and SNU]

*[https://web.archive.org/web/20110722145413/http://www.ieee.li/pdf/viewgraphs/wireless_mimo.pdf Dr. Jacob Sharony, "Introduction to Wireless MIMO – Theory and Applications", IEEE LI, 15 November 2006]

# [http://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_49/Docs/R1-072401.zip 3GPP, R1-072401, User Grouping Method for PU2RC Downlink MU-MIMO, Alcatel-Lucent]

*[http://www.ll.mit.edu/publications/journal/pdf/vol15_no1/15_1mimo.pdf Daniel W. Bliss, Keith W. Forsythe, and Amanda M. Chan, MIMO Wireless Communication, VOLUME 15, NUMBER 1, 2005 LINCOLN LABORATORY JOURNAL]

==See also==

KNOL Article: [http://knol.google.com/k/james-sungjin-kim/pu2rc/2ycwib2vxc76q/90 Kim, James Sungjin. PU2RC:Per-user unitary and rate control (Web). Version 4. Knol. 2009 Oct 17. Available from: http://knol.google.com/k/james-sungjin-kim/pu2rc/2ycwib2vxc76q/90.]

[[Category:3GPP]]

[[Category:IEEE 802]]

[[Category:Information theory]]

[[Category:Radio resource management]]

[[ko:PU2RC]]