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Improving the Efficiency of Control Signaling in Wireless Multiple Access Systems
Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Prior to the transmission of payload data in any multiple access system, there is generally a need to send control information such as scheduling assignments, transmission parameters and HARQ acknowledgments. This process is called control signaling and has a significant impact on the overall system performance. This dissertation considers different aspects of control signaling and proposes some novel schemes for improving it. The dissertation is split into two parts where in the first part the focus is on the transmission of scheduling assignments, and in the second part the focus is on improving the “blind decoding” process that is used to achieve adaptive coding and modulation in transmission of control information.

More specifically, in the first part of the dissertation we first compare the two conventional schemes for control signaling using extensive system simulations. In doing so, we use practical assumptions on the scheduling algorithm as well as on the compression and transmission of the scheduling information. We then provide two schemes for reducing the amount of control signaling that concerns the transmission of scheduling assignments. The first scheme, which is reminiscent of source coding with side information, uses the knowledge that each user has about its own channel condition to compress the scheduling information more effectively. The second scheme uses the fact that in wireless multiple access systems, a user with a given channel condition can in principle decode the data intended to the users that have weaker channels. Therefore, the idea is to send the scheduling information of different terminals in a differential manner starting from the user with the weakest channel and letting all the terminals overhear the transmission of one another. Finally, in the last section of this part we use some of the recent results in information theory to form a general framework for the comparison of different control signaling schemes. We formulate an optimization problem that for a given desired error probability finds the minimum required number of channel uses for a given signaling scheme.

In the second part of the thesis, we propose three schemes for reducing the complexity of the blind decoding process. The first one is a novel scheme for fast blind identification of channel codes. More precisely, we propose an efficient algorithm that for a given sequence of received symbols and a given linear channel code, finds the posterior probability that all the parity check relations of the code aresatisfied. We then use this quantity to perform a sequential statistical hypotheses test that reduces the computational complexity of blind decoding. The idea in the second scheme is to broadcast a control message prior to the transmission of control information to instruct only a subset of the terminals (ideally only those terminals that have been scheduled for reception of payload data and hence benefit from performing a blind search attempt) to perform blind search decoding, which can be used for instance in LTE to reduce the complexity of the blind decoding process. Finally, in the third scheme we propose to split the CRC, used by the terminals to find their control information, into two parts and inject one part early in the control data stream so that the terminals can detect early if the current decoding attempt will be successful, which ultimately reduces the blind decoding complexity.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. , 36 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1556
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-102537DOI: 10.3384/diss.diva-102537ISBN: 978-91-7519-477-6 (print)OAI: oai:DiVA.org:liu-102537DiVA: diva2:678886
Public defence
2014-01-17, Visionen, B-huset, Campus Valla, Linköpings universitet, Linköping, 13:15 (English)
Opponent
Supervisors
Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2016-08-31Bibliographically approved
List of papers
1. Comparison of Strategies for Signaling of Scheduling Assignments in Wireless OFDMA
Open this publication in new window or tab >>Comparison of Strategies for Signaling of Scheduling Assignments in Wireless OFDMA
Show others...
2010 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 59, no 9, 4527-4542 p.Article in journal (Refereed) Published
Abstract [en]

This paper considers transmission of scheduling information in  OFDMA-based cellular communication systems such as 3GPP long-term  evolution (LTE). These systems provide efficient usage of radio  resources by allowing users to be scheduled dynamically in both  frequency and time. This requires considerable amounts of scheduling  information to be sent to the users.  The paper compares two basic transmission strategies: transmitting a  separate scheduling message to each user versus broadcasting a joint  scheduling message to all users. Different scheduling granularities  are considered, as well as different scheduling algorithms. The  schemes are evaluated in the context of the LTE downlink using  multiuser system simulations, assuming a full-buffer situation.  The results show that separate transmission of the scheduling  information requires a slightly lower overhead than joint  broadcasting, when proportional fair scheduling is employed and the  users are spread out over the cell area. The results also indicate  that the scheduling granularity standardized for LTE provides a good  trade-off between scheduling granularity and overhead.

Place, publisher, year, edition, pages
IEEE, 2010
Keyword
Control signaling, resource allocation in wireless OFDMA, signaling of scheduling assignments, signaling overhead
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-58156 (URN)10.1109/TVT.2010.2066589 (DOI)000284087700029 ()
Note
©2010 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Reza Moosavi, Jonas Eriksson, Erik G. Larsson, Niclas Wiberg, Pål Frenger and Fredrik Gunnarsson, Comparison of Strategies for Signaling of Scheduling Assignments in Wireless OFDMA, 2010, IEEE Transactions on Vehicular Technology. http://dx.doi.org/10.1109/TVT.2010.2066589 Available from: 2010-08-09 Created: 2010-08-09 Last updated: 2017-12-12
2. Reducing Physical Layer Control Signaling Using Mobile-Assisted Scheduling
Open this publication in new window or tab >>Reducing Physical Layer Control Signaling Using Mobile-Assisted Scheduling
2013 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 12, no 1, 368-379 p.Article in journal (Refereed) Published
Abstract [en]

We present a scheme for reducing the part of the downlink signaling  traffic in wireless multiple access systems that contains scheduling  information.  The theoretical basis of the scheme is that the  scheduling decisions made by the base station are correlated with  the CSI reports from the mobiles.  This correlation can be exploited  by the source coding scheme that is used to compress the scheduling  maps before they are sent to the mobiles. In the proposed scheme,  this idea is implemented by letting the mobiles make tentative  scheduling decisions themselves, and then letting the base station  transmit "agreement maps" instead of raw scheduling maps to the  mobiles.  The agreement maps have lower entropy and they require  less resources to be transmitted than the original scheduling maps  do. The improvement can be substantial.  We also model the task of  finding the optimal scheduling assignments according to the proposed  scheme as a combinatorial optimization problem and present an  efficient algorithm to find the optimal solution.

Place, publisher, year, edition, pages
IEEE, 2013
Keyword
Mobile-assisted scheduling; Control signaling; Resource allocation; Signaling overhead
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-68071 (URN)10.1109/TWC.2012.120312.120680 (DOI)000314178100035 ()
Available from: 2011-05-10 Created: 2011-05-10 Last updated: 2017-12-11
3. Differential Signaling of Scheduling Information in Wireless Multiple Access Systems
Open this publication in new window or tab >>Differential Signaling of Scheduling Information in Wireless Multiple Access Systems
2010 (English)In: Proceedings of the IEEE Global Communications Conference (GLOBECOM), 2010, 1-6 p.Conference paper, Published paper (Refereed)
Abstract [en]

This paper considers the control signaling on the downlink in wireless multiple access systems, with focus on the part of the control signaling that carries information on the user's time/frequency scheduling assignments. A new idea is presented to reduce the amount of channel resources needed for this signaling. The idea is to exploit the fact that provided that only one single user is scheduled on each channel resource, then the different users' scheduling assignments are correlated. This correlation can be exploited by encoding the scheduling information differentially. In order to recover the scheduling information, a user must then decode the scheduling information of some of the others. This is possible, because on the downlink, all users can hear the transmission by the base station so that users with a high SNR may decode the control signaling sent to users with a lower SNR. We present a practical scheme to exploit this idea. Both analytical analysis and numerical examples illustrate that the proposed technique can provide a substantial reduction in signaling traffic.

Series
Global Telecommunications Conference, ISSN 1930-529X
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-57630 (URN)10.1109/GLOCOM.2010.5683176 (DOI)978-1-4244-5637-6 (ISBN)978-1-4244-5636-9 (ISBN)
Conference
The IEEE Global Communications Conference (GLOBECOM), 06-10 December, Miami, FL, USA
Note
©2010 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.: Reza Moosavi, Jonas Eriksson and Erik G. Larsson, Differential Signaling of Scheduling Information in Wireless Multiple Access Systems, 2010, Proceedings of the IEEE Global Communications Conference 2010 (GLOBECOM 2010).Available from: 2010-06-24 Created: 2010-06-24 Last updated: 2016-08-31Bibliographically approved
4. Optimized Encoding of Scheduling Assignments Using Finite Blocklength Coding Bounds
Open this publication in new window or tab >>Optimized Encoding of Scheduling Assignments Using Finite Blocklength Coding Bounds
2014 (English)In: Wireless Communications Letters, IEEE, ISSN 2162-2337, Vol. PP, no 99, 1-4 p.Article in journal (Refereed) Published
Abstract [en]

We provide an analytical framework for optimizing the resources required for signaling of control information in wireless multiple access systems. In doing so, we use recent results in information theory, namely a new bound on the achievable rate in the finite blocklength regime by Polyanskiy. We formulate optimization problems for finding the minimum required number of channel uses such that the overall error probability in decoding the control information is below a given threshold for three different control signaling schemes.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-102534 (URN)10.1109/WCL.2014.022314.140009 (DOI)
Note

On the day of the defence date the status of this article was Manuscript.

Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2016-08-31Bibliographically approved
5. Fast Blind Recognition of Channel Codes
Open this publication in new window or tab >>Fast Blind Recognition of Channel Codes
2014 (English)In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 62, no 5, 1393-1405 p.Article in journal (Refereed) Published
Abstract [en]

We present a fast algorithm that, for a given input sequence and a linear channel code, computes the syndrome posterior probability (SPP) of the code, i.e., the probability that all parity check relations of the code are satisfied. According to this algorithm, the SPP can be computed blindly, i.e., given the soft information on a received sequence we can compute the SPP for the code without first decoding the bits. We show that the proposed scheme is efficient by investigating its computational complexity.

We then consider two scenarios where our proposed SPP algorithm can be used. The first scenario is when we are interested in finding out whether a certain code was used to encode a data stream. We formulate a statistical hypothesis test and we investigate its performance. We also compare the performance of our scheme with that of an existing scheme. The second scenario deals with how we can use the algorithm for reducing the computational complexity of blind decoding process, the process that, for instance, is used by terminals in LTE for detection of control information. We propose a heuristic sequential statistical hypotheses test to use the fact that in real applications, the data arrives sequentially, and we investigate its performance using system simulations.

Place, publisher, year, edition, pages
IEEE, 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-102536 (URN)10.1109/TCOMM.2014.050614.130297 (DOI)000338028300001 ()
Note

On the day of the defence date the status of this article was Manuscript.

Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2017-12-06Bibliographically approved
6. Fast Identification of Control Signaling Aided by Please-Decode-Blindly (PDB) Messages
Open this publication in new window or tab >>Fast Identification of Control Signaling Aided by Please-Decode-Blindly (PDB) Messages
2012 (English)In: 2012 Swedish Communication Technologies Workshop (Swe-CTW), IEEE Press, 2012, 53-58 p.Conference paper, Published paper (Refereed)
Abstract [en]

Blind decoding of control information is used in some wireless  multiple access systems such as LTE to achieve adaptive modulation  and coding, as well as to address the multiple access problem on the  control channel. Blind decoding incurs high computational complexity in mobile terminals. In this paper, we describe a scheme to reduce  the computational complexity associated with the blind decoding. The  main idea is to broadcast a "please-decode-blindly" message to all  terminals that are eligible for scheduling, to instruct a subset of  the terminals to perform the blind search. We propose two schemes to  implement our idea and we investigate their performances via system  simulations.

Place, publisher, year, edition, pages
IEEE Press, 2012
Keyword
Blind decoding, Adaptive coding and modulation, Control signaling
National Category
Communication Systems
Identifiers
urn:nbn:se:liu:diva-82104 (URN)10.1109/Swe-CTW.2012.6376289 (DOI)978-1-4673-4762-4 (ISBN)978-1-4673-4761-7 (priint) (ISBN)
Conference
IEEE Swedish Communication Technologies Workshop (Swe-CTW), 24-26 October, Lund, Sweden
Available from: 2012-09-30 Created: 2012-09-30 Last updated: 2016-08-31Bibliographically approved
7. Complexity Reduction of Blind Decoding Schemes Using CRC Splitting
Open this publication in new window or tab >>Complexity Reduction of Blind Decoding Schemes Using CRC Splitting
2012 (English)In: 2012 IEEE Global Communications Conference (GLOBECOM), IEEE , 2012, 3731-3736 p.Conference paper, Published paper (Refereed)
Abstract [en]

Blind decoding, used on control channels of some multi-user wireless  access systems, is a technique for achieving adaptive modulation and  coding. The idea is to adapt the modulation and coding scheme to the  channel quality but instead of signaling the parameters used  explicitly, the receiver blindly tries a number of fixed parameter  combinations until a successful decoding attempt is detected, with  the help of a cyclic redundancy check. In this paper we suggest a  new method for reducing the complexity and energy consumption  associated with such blind decoding schemes. Our idea is to use a  mini-CRC injected early in the data stream to determine if the  current decoding attempt is using the correct modulation and coding  parameters. We analyze and exemplify the complexity gain of this  approach and also investigate the impact of the rearrangement of the  CRC scheme in terms of the probability of undetected error. The  presented results for the complexity gain are promising and the  impact on the error detection capability turns out to be small if  any.

Place, publisher, year, edition, pages
IEEE, 2012
Series
IEEE Global Communications Conference, Exhibition, & Industry Forum (GLOBECOM), ISSN 1930-529X
Keyword
Blind decoding, Adaptive coding and modulation, CRC splitting, Code detection
National Category
Communication Systems
Identifiers
urn:nbn:se:liu:diva-79226 (URN)10.1109/GLOCOM.2012.6503697 (DOI)978-1-4673-0919-6 (ISBN)978-1-4673-0920-2 (ISBN)
Conference
IEEE GLOBECOM 2012, 3-7 Dec 2012, Anaheim, California, USA
Available from: 2012-07-03 Created: 2012-07-03 Last updated: 2016-08-31Bibliographically approved

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