Galli S.,Panasonic |
Galli S.,ASSIA Inc |
Scaglione A.,University of California at Davis |
Wang Z.,University of Illinois at Urbana - Champaign
Proceedings of the IEEE | Year: 2011
Are Power Line Communications (PLC) a good candidate for Smart Grid applications? The objective of this paper is to address this important question. To do so, we provide an overview of what PLC can deliver today by surveying its history and describing the most recent technological advances in the area. We then address Smart Grid applications as instances of sensor networking and network control problems and discuss the main conclusions one can draw from the literature on these subjects. The application scenario of PLC within the Smart Grid is then analyzed in detail. Because a necessary ingredient of network planning is modeling, we also discuss two aspects of engineering modeling that relate to our question. The first aspect is modeling the PLC channel through fading models. The second aspect we review is the Smart Grid control and traffic modeling problem which allows us to achieve a better understanding of the communications requirements. Finally, this paper reports recent studies on the electrical and topological properties of a sample power distribution network. Power grid topological studies are very important for PLC networking as the power grid is not only the information source but also the information delivery systema unique feature when PLC is used for the Smart Grid. © 2011 IEEE.
Bhagavatula R.,ASSIA Inc |
Heath R.W.,University of Texas at Austin
IEEE Transactions on Wireless Communications | Year: 2013
Base station cooperation can use knowledge of the users' channel state information (CSI) at the transmitters to manage co-channel interference. A reasonable way to provide CSI to the base stations is through a finite rate limited feedback channel. Existing multicell limited feedback techniques require a large amount of feedback, which incurs an overhead penalty on the uplink. In this paper, a new feedback approach based on predictive vector quantization (PVQ) is proposed to reduce feedback requirements in multicell systems and provide high resolution CSI at base stations by exploiting temporal correlation in the channels. Transmitter and receiver structures are proposed to implement predictive limited feedback accounting for delay, for signals on the Grassmann manifold. Simulations show that the proposed PVQ framework yields higher sum-rates than memoryless quantization approaches for multicell limited feedback, in a cooperative system using intercell interference nulling. © 2002-2012 IEEE.
Galli S.,ASSIA Inc
IEEE Transactions on Communications | Year: 2011
We report here that channel power gain and Root-Mean-Square Delay Spread (RMS-DS) in Low/Medium Voltage power line channels are negatively correlated lognormal random variables. Further analysis of other wireline channels allows us to report a strong similarity between some properties observed in power line channels and the ones observed in other wireline channels, e.g. coaxial cables and phone lines. For example, it is here reported that channel power gain and logarithm of the RMS-DS in DSL links are linearly correlated random variables. Exploiting these results, we here propose a statistical wireline channel model where tap amplitudes and delays are generated in order to reflect these physical properties. Although wireline channels are considered deterministic as their impulse response can be readily calculated once the link topology is known, a statistical wireline channel model is useful because the variability of link topologies and wiring practices give rise to a stochastic aspect of wireline communications that has not been well characterized in the literature. Finally, we also point out that alternative channel models that normalize impulse responses to a common (often unitary) power gain may be misleading when assessing the performance of equalization schemes since this normalization artificially removes the correlation between channel power gain and RMS-DS and, thus, Inter-Symbol Interference (ISI). © 2011 IEEE.
Bhagavatula R.,ASSIA Inc |
Heath Jr. R.W.,University of Texas at Austin
IEEE Transactions on Signal Processing | Year: 2011
Base station cooperation can exploit knowledge of the users' channel state information (CSI) at the transmitters to manage co-channel interference. Users have to feedback CSI of the desired and interfering channels using finite-bandwidth backhaul links. Existing codebook designs for single-cell limited feedback can be used for multicell cooperation by partitioning the available feedback resources between the multiple channels. In this paper, a new feedback-bit allocation strategy is proposed, as a function of the delays in the communication links and received signal strengths in the downlink. Channel temporal correlation is modeled as a function of delay using the Gauss-Markov model. Closed-form expressions for bit partitions are derived to allocate more bits to quantize the stronger channels with smaller delays and fewer bits to weaker channels with larger delays, assuming random vector quantization. Cellular network simulations are used to show that the algorithm presented in the paper yields higher sum-rates than the equal-bit allocation technique. © 2011 IEEE.
Cioffi J.M.,Stanford University |
Cioffi J.M.,ASSIA Inc
IEEE Communications Magazine | Year: 2011
This invited "History of Communications" paper provides a perspective on the many contributions and achievements to the science of high-speed transmission on telephone-line copper twisted-pair. This perspective relies largely on the author's 30-year academic and industrial DSL working experience, but nevertheless attempts to include key events and mention key individuals in the steady march from the kilobits/second of voiceband modems to the Gigabits/second of today's copper connections over those three-plus decades. Digital Subscriber Lines (DSL) and its ancestors are emphasized, while some Ethernet contributions to DSL are also cited. © 2010 IEEE.
Zahedi-Ghasabeh A.,ASSIA Inc |
Tarighat A.,Broadcom Corporation |
Daneshrad B.,University of California at Los Angeles
IEEE Transactions on Vehicular Technology | Year: 2012
Given the widespread deployment of orthogonal frequency-division multiplexing (OFDM)-based wireless systems, reliable spectrum sensing of OFDM waveforms is of great interest for future cognitive radio systems. Use of the embedded pilots of OFDM signals has been extensively studied in the literature. Such techniques rely on having correlated pilots to improve detection sensitivity. However, the impact of synchronization in accuracy and implementation impairments has not been thoroughly studied in the literature. This paper discusses the pilot-aided cyclostationary detection (PACSD) method as a practical structure to detect OFDM signals under asynchronous conditions. The presented analysis quantifies the performance of a detection method without exhaustive searching, compared with an ideal system. This paper goes on to investigate the impact of radio-frequency (RF) front-end nonidealities on the overall performance of the PACSD. We develop closed-form expressions for performance loss in the presence of in-phase/quadrature (I/Q) imbalance, carrier frequency offset, phase noise, and sampling clock frequency offset (SCFO). These results show that the most detrimental impairment is that of SCFO, where a 20-ppm offset can result in a 9-dB performance loss. We then present a modified detector structure to compensate for this huge loss. Analysis and simulation show that, using the modified technique, we can get within 2 dB of the ideal no-offset case. © 2006 IEEE.
ASSIA Inc | Date: 2012-10-12
Time division duplex transmission over copper physical channels is managed. In one example, upstream time slots for upstream transmission in a first physical channel are scheduled. Downstream time slots for downstream transmission in a second physical channel are scheduled. Transmission in the upstream time slots is substantially not simultaneous with transmission in the downstream time slots.
News Article | November 27, 2014
BT denies the performance of its broadband networks, including its superfast fibre ones, will be affected as a result of it discontinuing the use of some technology following a patent dispute. The dispute with US company ASSIA goes back to 2011, when ASSIA claimed that BT had infringed three of its broadband performance patents, which BT had denied. ASSIA wanted BT to license the technology in all three cases, and also threatened BT with a damages claim if it didn't come to an arrangement. A BT spokesperson said: "BT has been defending a claim brought by ASSIA since November 2011. They had asserted three patents against BT but during the proceedings, they had to narrow their allegations and withdraw one of these patents entirely." BT added: "In January 2014, the High Court found BT was infringing on only a minor part of one patent, and the Court of Appeal, whilst invalidating the majority of the claims of ASSIA's other patent, ruled that BT's network infringes what remains of the other patent. "Although BT was disappointed with the ruling, we have made minor changes to our programming which means these two decisions have no material effect on the operation or performance of our networks." If BT had not made these changes from last Friday morning - which focused on the area of dynamic line management - it was threatened with a damages claim by the court of £250,000 per week. ASSIA may still come after BT for past use of the patents in dispute though. International law firm Wragge Lawrence Graham & Co is advising ASSIA on the "ongoing dispute". Wragge Lawrence Graham & Co IP partner David Barron said: "This latest judgment from the Court of Appeal further vindicates ASSIA's determination to seek proper recompense for BT's use of ASSIA's cutting-edge DSL technology." ASSIA said it will "now proceed with its claim for damages, which it believes will amount to many millions of pounds". It added: "BT has been refused permission to appeal, but has yet to indicate whether it will seek permission directly from the Supreme Court." BT broadband customers will no doubt also be keeping a close eye on whether their broadband service suffers or not as a result of BT's network modifications. ASSIA says other broadband providers already license its software.
News Article | October 1, 2013
AT&T said on Tuesday that its planned gigabit network set for Austin is both real and that the early stages of it will start operating on December 1. Ma Bell today launched a portal where residents can express interest in the service and said it would start offering what it calls its AT&T U-verse with GigaPower service with a symmetrical 300 Mbps option. By the middle of 2014 AT&T says residents with the GigaPower service will have a symmetrical gigabit connection. No word on the price or whether it will be capped. This puts Austin in a unique spot among cities — with two companies preparing to lay two gigabit, fiber-to-the-home networks in the self-proclaimed Live Music Capital of the world. There’s this effort from AT&T, and the planned Google Fiber deployment, which many view as the impetus for AT&T’s original announcement. Google said at the time it plans to connect its first customers by mid-2014, which perhaps not coincidentally is when AT&T will have its first customers upgraded to a gigabit at no additional costs to the yet-to-be-determined-price, according to Lori Lee, executive vice president, AT&T Home Solutions. Lee didn’t explain how AT&T would get from today’s U-Verse speeds that top out at 24 Mbps downstream to 300 Mbps on their way to true gigabit connectivity. AT&T’s current network in Austin is a very-high-bit-rate digital subscriber line (VDSL) network which means it has fiber deployed to nodes in each neighborhood, but uses copper phone lines to make the final hop to homes. I asked Dr. George Ginis, SVP of DSL marketing at ASSIA and the inventor of vectoring, if AT&T’s current lines could be pushed to 300 Mbps or even a gig. He explained that there are technologies that can get a VDSL network to about 200 Mbps using the typical equipment U.S. telcos have deployed. One technology, called vectored VDSL allows speeds of up to 100 Mbps, while another uses bonding to deliver speeds of up to 200 Mbps on the double-twisted-pair (it has four wires) copper networks in use in many parts of the U.S. There is a technology called G.fast that could deliver gigabit speeds, but that’s not standardized yet. So it sounds like in Austin at least AT&T is going to really deploy fiber to the home for gigabit customers. AT&T’s GigaPower customers have the option of TV, voice and “the possibility of integrated mobile service” with their service as well. Unfortunately Lee wasn’t as forthcoming with other details, such as pricing. That’s fine, because it’s not like we know how Google plans to price its broadband or its broadband and TV offering (Google in its other cities does not offer a voice service perhaps because if you have broadband you already have access to VoIP without paying Google a fee). It’s not clear if Lee’s voice service will be VoIP-based or still use the copper wiring AT&T already has in the home (for now anyway). Also unclear is how AT&T plans to roll out the service and where. The AT&T announcement is timed to the launch of a portal where users can sign up. Lee says that customers won’t have to pay a fee to commit to getting the service, as Google Fiber hopefuls in Kansas City did. In what appeared to be a dig at Google, Lee said “You can sign up and show your interest at any time. It’s not a one-time sign up.” Of course, since that social engineering and format of the competition helped Google create economies of scale that lowered its expenses for digging fiber, it seems AT&T is willing to forgo those advantages. And of course, we still don’t know how or where Google plans its own roll out. Plus, AT&T’s CEO Randall Stephenson said last week at an investor conference that because the cost of deploying fiber has dropped by so much, he thinks it will deploy faster networks in cities other than Austin. What those costs are is hard to say. Lee didn’t comment. Google has never commented. I’ve heard estimates from $6,424 from the man who invented DSL to as low as $450 from industry observers. So basically, Austinites now have two web sites where they can enter their information to sign up for proposed gigabit networks. AT&T’s apparently will go live at less than a third of the speed perhaps as a way of gauging demand and helping set price expectations in the market. Since Google’s spokespeople have told me that part of the pricing for Google Fiber factors in the price it pays for broadcast rights as part of the TV package, and AT&T already has those deals, perhaps it’s willing to undercut Google to win in Austin. Also if it ties subscribers to a contract, those who sign up for the December service, might not be in a position to sign up for Google’s fiber, which might disrupt Google’s costs. Meanwhile, we have no technical details, no pricing, no indication of where the network will launch and no idea what a gig could even do for us. Yet, I can still find people who are over the moon with excitement.
News Article | January 28, 2015
Indian Stainless Steel Development Organisation (ISDO) organized world’s biggest integrated stainless steel exhibition –INDINOX 2015 – from 24th to 27th January 2015 at Mahatma Mandir, Gandhinagar, Gujarat. This B2B Fair received tremendous success with a footfall of more than one lakh visitors. INDINOX 2015 was inaugurated by Hon’ble Chief Minister of Gujarat, Smt. Anandiben Patel. Shri Narendrasingh Tomar- Union Minister of Mines & Steel was the Chief Guest during the inaugural function. The inaugural event was graced by Shri Devji Patel-MP, Shri Vijay Sharma –Vice President (sales & Marketing) of Jindal Stainless Ltd. (JSL), Shri Rajendra Shah –Chairman of Shah Alloys Ltd., Shri N.C. Mathur – President of ISSDA etc. The inaugural function was blessed by His Holiness Gurudev Shri Guruvandanaji. Mr. Makus Moll –MD of SMR-Austria and Mr. Austin Lu- President of Stainless APAC of China were the distinguished guests of the event. Mr. Ugamraj Hundia, Chairman of ISDO stated that first INDINOX event was held in the year 2010 at Ahmedabad, which was a great success. INDINOX 2015 was on a larger scale and achieved much greater level of success. INDINOX 2015 had more than 1,000 stalls, including 50 international exhibitors & participants. World’s first ever stainless steel arts festival was one of the main attraction of INDINOX 2015. An international conference and Knowledge Seminar was held on 25th January 2015. There was also stainless steel buyers & sellers meet as well as networking dinner. Stainless steel industry’s centenary celebrations formed a part of INDINOX 2015. It also included recognition of major players with Award Night. INDINOX 2015 was organized by Indian Stainless Steel Development Organisation (ISDO) and supported by Govt. of Gujarat, ISSDA, SAIL, Gujarat Chamber of Commerce & Industry, Ministry of Micro-Small & Medium Enterprises (MSME), Indian Railway, Metal and Stainless Steel Merchants Association, ASSIA, INDEXTb and Steel Market Info.ISDO is supporting our Prime Minister Shri Narendra Modi’s campaign “Make in India”. Mr. Kushal V. Bhansali, Chief Convener of ISDO Exhibition Committee informed that ISDO has entered into an MOU with Gujarat govt. during Vibrant Gujarat Summit for setting up Stainless Steel Industrial Park as well as Exhibition Park at Sanand in Gujarat. Around 50 top manufacturing companies would participate in the industrial park. The project cost would be around Rs. 350 to Rs. 400 crore. The land was already allotted by Gujarat Government and project was expected to be completed in about two years time. Photo caption: During the inauguration, seen from left to right, Shri Rajendra Shah-Chairman of Shah Alloys, Shri Vijay Sharma- Vice President of JSL Ltd., Smt. Anandiben Patel- Chief Minister of Gujarat, His Holiness Gurudev Shri Guruvandanaji, Shri Narendra Singh Tomar- Union Minister of Mines & Steel and Shri Devraj Patel- MP