BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:Europe/Stockholm BEGIN:DAYLIGHT DTSTART:20240331T030000 TZOFFSETFROM:+0100 TZOFFSETTO:+0200 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3 TZNAME:CEST END:DAYLIGHT BEGIN:STANDARD DTSTART:20241027T020000 TZOFFSETFROM:+0200 TZOFFSETTO:+0100 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:CET END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20241026T090948Z UID:2A0F1B91-71D1-48A5-B8E9-3844AEF21FFB DTSTART;TZID=Europe/Stockholm:20241023T133000 DTEND;TZID=Europe/Stockholm:20241023T143000 DESCRIPTION:Title:\n\nPrivate Information Retrieval at 1 bit/sec/Hz of the Unconstrained Capacity of the Gaussian MAC and Some Results on Covert Cont rol of a Linear System\n\nAbstract:\n\nIn Private Information Retrieval (P IR)\, there are N replicated non-communicating databases containing the sa me M messages\, and a user who wishes to retrieve one of the messages with out revealing the message's index to the databases. In most cases\, one as sumes orthogonal\, error free links between the user and the databases. In this talk\, we will assume a shared medium between the user and the datab ases. Specifically\, a block-fading Additive White Gaussian Noise Multiple Access Channel (AWGN MAC). We will review some previously known results o n PIR in general\, show how a separated coding scheme fails to achieve opt imal performance in this case\, then propose a joint channel-PIR coding sc heme whose rate scales with both the number of databases N and the power P similarly to the channel capacity without the privacy constraint. Further more\, the analysis reveals that the proposed scheme has only a finite gap from this unconstrained channel capacity: 1 bit/sec/Hz as N increases.\n\ nWe will then turn to consider a different problem\, that of covertly cont rolling a linear system. In this problem\, Alice desires to control (stabi lize or change the behaviour of) a linear system\, while keeping an observ er\, Willie\, unable to decide if the system is indeed being controlled or not. We will formally define the problem\, under a model where Willie can only observe the system's output. Focusing on AR(1) systems\, we will sho w that when Willie observes the system's output through a clean channel\, an inherently unstable linear system can not be covertly stabilized. Howev er\, under some conditions on the parameters and observation time\, an inh erently stable linear system can be covertly controlled\, in the sense of covertly changing its parameter or resetting its memory. Moreover\, we wil l give positive and negative results for two important controllers: a mini mal-information controller\, where Alice is allowed to use only 1 bit per sample\, and a maximal-information controller\, where Alice is allowed to view the real-valued output. The results reveal an interesting interplay i n covert control\, between the amount of information used by the controlle r\, control performance and covertness.\n\nJoint work with Or Elimelech an d Barak Amihood.\n\nCo-sponsored by: Onur Günlü\, Information Coding Div ision (ICG)\, LiU\n\nSpeaker(s): Prof. Asaf Cohen\n\nRoom: Systemet\, Bldg : B-Huset\, Linköping University\, LiU Valla Campus\, Linköping\, Osterg otlands lan\, Sweden\, Virtual: https://events.vtools.ieee.org/m/440864 LOCATION:Room: Systemet\, Bldg: B-Huset\, Linköping University\, LiU Valla Campus\, Linköping\, Ostergotlands lan\, Sweden\, Virtual: https://event s.vtools.ieee.org/m/440864 ORGANIZER:onur.gunlu@liu.se SEQUENCE:15 SUMMARY:IEEE Technical Seminar on Private Information Retrieval at Linköpi ng University by Prof. Asaf Cohen URL;VALUE=URI:https://events.vtools.ieee.org/m/440864 X-ALT-DESC:Description: <br /><p><strong>Title:&nbsp\;</strong></p>\n<p>Pri vate Information Retrieval at 1 bit/sec/Hz of the Unconstrained Capacity o f the Gaussian MAC and Some Results on Covert Control of a Linear System</ p>\n<p><strong>Abstract:&nbsp\;</strong></p>\n<p>In Private Information Re trieval (PIR)\, there are N replicated non-communicating databases contain ing the same M messages\, and a user who wishes to retrieve one of the mes sages without revealing the message's index to the databases. In most case s\, one assumes orthogonal\, error free links between the user and the dat abases. In this talk\, we will assume a shared medium between the user and the databases. Specifically\, a block-fading Additive White Gaussian Nois e Multiple Access Channel (AWGN MAC). We will review some previously known results on PIR in general\, show how a separated coding scheme fails to a chieve optimal performance in this case\, then propose a joint channel-PIR coding scheme whose rate scales with both the number of databases N and t he power P similarly to the channel capacity without the privacy constrain t. Furthermore\, the analysis reveals that the proposed scheme has only a finite gap from this unconstrained channel capacity: 1 bit/sec/Hz as N inc reases.<br>&nbsp\;<br>We will then turn to consider a different problem\, that of covertly controlling a linear system. In this problem\, Alice desi res to control (stabilize or change the behaviour of) a linear system\, wh ile keeping an observer\, Willie\, unable to decide if the system is indee d being controlled or not. We will formally define the problem\, under a m odel where Willie can only observe the system's output. Focusing on AR(1) systems\, we will show that when Willie observes the system's output throu gh a clean channel\, an inherently unstable linear system can not be cover tly stabilized. However\, under some conditions on the parameters and obse rvation time\, an inherently stable linear system can be covertly controll ed\, in the sense of covertly changing its parameter or resetting its memo ry. Moreover\, we will give positive and negative results for two importan t controllers: a minimal-information controller\, where Alice is allowed t o use only 1 bit per sample\, and a maximal-information controller\, where Alice is allowed to view the real-valued output. The results reveal an in teresting interplay in covert control\, between the amount of information used by the controller\, control performance and covertness.<br>&nbsp\;<br >Joint work with Or Elimelech and Barak Amihood.</p>\n<p>&nbsp\;</p> END:VEVENT END:VCALENDAR