Date: May 14, 2014 Source: PR Wire (
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Despite many failed attempts, the elusive RFID based shopping-cart checkout is now entirely possible - a real breakthrough in RFID. Both the technology and methodology now exist for making cost effective tags that have enough range to be read as the cart passes through a reader bay. In order to overcome limitations of existing technology and allow for successful shopping-cart checkout, or item-level tagging, the following criteria must be met:
Cost, size, and power must all be significantly reduced to enable ubiquitous use of tags
Transmission ranges need to vastly increase from their current 15 cm to one meter
A new technology that enables RFID shopping-cart checkout has been created. The trick is to keep die size and antenna dimensions small while achieving a one meter transmit range with low transmit power. This new technology reduces current, comparable, tag die sizes to less than one tenth of comparable quadrature die, via a simpler architecture with much fewer stages, which also reduces power. By keeping the required Signal-to-Noise Ratio (SNR) small on the receiver (increased sensitivity), the antenna dimensions can also be kept equal to the small die size and lower transmit power to achieve comparable distances that RFID currently do with much larger antennae dimensions and higher power. Thus it will transmit roughly 10 times further than today's archaic solution, extending the current prohibitive 15 cm (6 inch) range (given small enough die and antenna dimensions to qualify as an item tag) well into the far-field range approaching one meter (several feet) required for item-level tagging or shopping-cart RFID - meeting both criteria.
This advancement will enable the shopping-cart checkout as well as receiving and instantaneous inventorying. The overall cost reduction over current methods of check out and inventory will be large. For instance, because of near instantaneous check out from RFID, the queues and manual operation inherent in current serial check out methods will be greatly reduced or effectively eliminated. Likewise, inventorying will eliminate manual operations and reduce to an almost simultaneous accounting for all tagged items.
In order to productize this technology, several things must happen. A modulation scheme needs to meet the criterion listed above and the industry must standardize on such a viable solution. Because the criteria cannot be met with existing methods, this new technology will be needed to create such a new market with item-level tagging.
Rest assured, a new industry standard won't be based on 802.11, nor any of the quadrature architectures commonly employed in RFID. Gen 2 tags, the proposed Electronic Product Code (EPC) [1] Global Class 1 Generation 2 methods of transmission, also have flaws that limit the range and ability to keep tag and antenna size small while transmitting the required distance into far field. Overall, the currently proposed standards using quadrature architectures are notorious for superfluously large tag or antenna sizes and reduced transmission ranges (less than 15 cm) due to poor Signal to Noise Ratio (SNR) [2]. This is the reason, that after years of trying, current efforts have failed to realize the required criteria for a shopping-cart solution.
Using Ultra Phase Modulation (UPM), a fast two-constellation Frequency Shift Key (FSK modulation), the criteria for a shopping-cart application can be met. FSK was once proposed as a possible transmission method for the 802.11 Wi-Fi standards yet it was abandoned in 1997 due to the limitations of the technology available at the time. Ultra Phase Modulation has overcome these limitations to a point where a CTO at a large semiconductor design company with an extensive background in wireless communication (who was on the original 802.11 committee) confirmed that Ultra Phase Modulation, or very fast FSK, can indeed achieve the far superior wireless performance over existing quadrature architectures as touted and demonstrated via simulation results.
Ultra Phase Modulation architecture is shown in Figure 1. By eliminating stages of quadrature receivers, the down-convert, quadrature synchronization, and Digital Signal Processing (DSP), all of the corresponding noise, die area and power consumption are also eliminated. The eliminated noise, the dominant channel noise resulting in the high SNR of quadrature receivers that severely limit their transmission range, allows the SNR of Ultra Phase Modulation to now be kept much lower. At much lower SNR the antenna dimensions per given meter range can also be kept low and on the order of the die size which also reduces by roughly 90% (also reducing power). Thus Ultra Phase Modulation meets the criteria for shopping-cart checkout via RFID, smaller size and cost, and longer transmission range.
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Figure 1. UPM eliminates noisy and area-consuming stages, to reduce size and power.
As a result of the advantages offered by this breakthrough technology, the RFID tag industry can now move towards longer transmission ranges that are roughly 10 times farther as depicted in Figure 2 The Ultra Phase Coordination produces much stronger signals (much less power dedicated to overcoming noise) thus enabling shopping-cart checkouts, and item-level tagging. The other criterion, the smaller die size can also be readily ascertained by the simplified architecture of Ultra Phase Modulation, which is roughly 10% of typical die area with correspondingly small antenna dimensions. This enables tags that are small enough for individualized tagging for massive inventories. Ultra Phase Modulation translates into greatly reduced cost, relative to the nickel per die cost of printing bar codes, keeping costs low as desired by the retail store economy [3]. Approaching these costs allows Ultra Phase Coordination to supplant the commonly used bar codes in inventorying and checkout.
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Figure 2. UPM improves transmission distances by orders of magnitude over quadrature architectures.
Conclusion
Ultra Phase Modulation has the inherent advantages needed to achieve the RFID shopping-cart checkout, or item-level tagging, as verified by longer transmission distances and significantly reduced size, cost, and power consumption versus existing methods. Such details can be further explained by contacting info@gainics.com.
