Abstract:
The present application includes a system and method that provisions at least two (2) receivers in a topology that allows each receiver to acquire wireless communication signals through different diverse antenna fields. Each receiver acquires the signal, and demodulates, decodes and sends data to the data terminal component. The data terminal component resolves packet alignment issues and selects the best data. This improves system reliability and reduces the system susceptibility to data corruption or loss of data due to signal fading that might occur on a single antenna field. Provisioning a wireless system in this manner reduces the likelihood that the same fading phenomena, resulting from either multipath and/or shadowing affects, impair signal reception causing data dropout or loss of data.

Description:
FIELD 
     The present application is directed to the field of wireless communication systems. More specifically, the present application is directed to the field of redundant signal reception in wireless medical monitoring systems. 
     BACKGROUND 
     In current wireless communication systems, there are problems of loss of data or data dropout of wireless medical telemetry services caused by fading. Fading refers to the deviation in the attenuation that a carrier-modulated RF signal experiences over a propagation media. The fades usually result from multipath propagation, (where different paths of the same signal combining in a destructive manner), or shadowing, (where obstacles obstruct the wave propagation). Fading models can be used to describe how fades might occur, but signal fading is a random phenomenon and cannot be eliminated from any wireless communication system. 
     Thus, it is desirable to reduce the probability that a signal fade will impact the performance of a wireless system. By reducing the probability that a fade causes a loss of data or data dropout in the system, the reliability of the wireless communication system is improved. 
     SUMMARY 
     The present application includes a system and method that provisions at least two (2) receivers in a topology that allows each receiver to acquire, decode and demodulate data from a wireless communication signal through different diverse antenna. Each receiver sends the acquired data to the data terminal component. The data terminal component resolves packet alignment issues and selects the best data. This approach improves system reliability and reduces the system susceptibility to data corruption or loss of data due to signal fading or dropout that might occur on a single received signal. Since the joint probability of a fade occurring simultaneously on two or more independent antenna fields is much less than any single field, provisioning a wireless system in this manner improves the chance to receive correct data because at least one of the antenna fields that are redundantly monitored by the receiver infrastructure will typically not be in a fade. 
     In one aspect of the present application, an enhanced quality of service wireless communication system comprises a primary receiver configured to receive a wireless signal including medical data transmitted from a wireless medical device, a redundant receiver configured to receive the wireless signal from the wireless medical device wherein each of the primary and redundant receivers include a decoder and a transfer media component, wherein the decoder evaluates the quality of the wireless signal and extracts the medical data, and the transfer media component processes the wireless signal into a plurality of transfer data packets, and a data terminal component, wherein the data terminal component receives the plurality of data transfer packets from each of the primary and redundant receivers, and merges the plurality of transfer data packets into a composite data stream. 
     In another aspect of the present application, a method of enhanced quality of service in a wireless communication system comprises receiving a wireless signal transmitted from a medical device in a primary receiver, receiving the wireless signal from the medical device in a redundant receiver wherein each of the primary and redundant receivers include a decoder and a transfer media component, wherein the method further comprises the decoder evaluating the quality of the received wireless signal, and extracts the medical data, and the transfer media component processing the received medical data into a plurality of transfer data packets, and receiving the plurality of data transfer packets from each of the primary and redundant receivers in a data terminal component, and further comprising merging the plurality of transfer data packets into a composite data stream. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic block diagram illustrating an embodiment of a receiver system of the present application. 
         FIG. 2  is a graphical representation illustrating an embodiment of multiple signals of the present application. 
         FIG. 3  is a graphical representation illustrating an embodiment of multipath fading of the present application. 
         FIG. 4  is a schematic block diagram illustrating an embodiment of a transfer data packet of the present application. 
         FIG. 5  is a schematic block diagram illustrating an embodiment of a data stream reconstruction of the present application. 
         FIG. 6  is a flow chart illustrating an embodiment of a method of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     The system and method of the present application involves the reception of a desired wireless communication signal through at least two different receiver paths, existing on either the same or unique physical receiver module. Referring to  FIG. 1 , redundant coverage in the receiver system  100  will involve signal reception from a primary receiver  110  and at least one redundant receiver  120 . In the context of this application, signal reception refers to the following functional elements: antenna diversity, selectivity, demodulation, decoding and transfer of the decoded information. The received data shall be transferred from the receiver, either the primary receiver  110  or the redundant receiver  120 , to a data terminal component  170  for reconstruction. In this embodiment, the data terminal component  170  is not required to be the final destination of the received data. The primary and redundant receivers  110 ,  120  offer the same performance characteristics, where the fundamental differences in reception results from antenna field diversity. 
     The receiver system  100  in  FIG. 1  includes antennas  115  in each of the receivers  110 ,  120  that receive communication from the overall wireless system (not shown). These antennas  115  are deployed as spatially diverse antenna fields located across the provisioned service area of the wireless system. The location of each antenna  115  is based on specific design rules and results from a site survey. Because each antenna  115  is installed in a different location, the signal at each antenna  115  represents a unique realization of the wireless signal at any point in time. However, it should also be noted that any of the plurality of primary  110  and/or redundant receivers  120  may be implemented in a single hardware component. 
     Configuring antennas  115  in this manner is particularly helpful for use with indoor systems where line-of-sight between a transmitting device and receiver is not necessary a clear path. In these situations, signals reflect off permanent obstacles or other objects as they radiate away from the source. These reflections, result in alternate signal paths between the transmitter and receivers  110 , and  120 , which can be referred to as multipath situations or signals. When these multipath signals are combined at the aperture of the antenna  115 , they can impact the quality of the received signal. The reflections introduce time-of-flight delays that manifest themselves as phase offsets in the received signal. This effect is illustrated in the multipath signal graph  200  in  FIG. 2 . This graph  200  shows that if a signal path is longer because of the number of reflections it will delay the signal arrival at the antenna aperture. The multipath signal graph  200  illustrates the original signal  230  and the delay signal  240  graphically, with a signal amplitude  220  along the y axis of the multipath signal graph  200 , over a time period  210  on the x axis of the multipath signal graph  200 . This multipath signal graph  200  illustrates how one signal from a transmitter in a wireless system may be received in a delayed fashion due to the effects of the environment. 
     Since there is currently no system or method to eliminate multipath signals in a wireless indoor environment, in some cases these effects can cause destructive interference and result in fading or reduced signal power of the received signal. This effect is illustrated in the antenna signal graph  300  in  FIG. 3 . This graph  300  presents an example of a signal fade situation that may occur in a typical wireless system. Here the received signal power  320  differs as received by two different antennas, antenna signal ( 1 )  330  and antenna signal ( 2 )  340 , verses time  310 . The signal power fades  335  are shown to occur at different times and represent reception through independent antenna fields. If reception of signal antenna ( 1 )  330  was used as the only signal for the receiver, as the signal faded  335 , and the receiver signal power  320  was reduced, the ability to demodulate the signal may become impaired. Using a single reception path through the receiver and antenna diversity provides advantages over a system using just a single antenna, because the receiver in a diverse system can detect the fade  335  and hand over reception to an alternate antenna. 
     Still referring to  FIG. 3 , in situations where fading is gradual, an antenna-switching algorithm in the receiver may detect the fade  335  and facilitate hand over of reception to another antenna, thus, preventing any dropout or degradation in performance. However, when the fades  335  occur rapidly, the antenna switching might not be capable of detecting the fade event  335  before degradation in performance manifests itself as a loss of data. Thus, reliability improvement of the wireless communication system may be achieved by the system and method of the present application that utilizes redundant reception on diverse antenna fields. This method will also prevent fast fades received on a single antenna from impairing performance of the receiver. 
     Referring again to  FIG. 1 , to consider redundant reception, the functional elements involved in a single reception path must be understood. These functional elements provide signal conditioning and implement signal processing techniques that allow the receiver  110 ,  120  to acquire the desired information as it was transmitted across a communication channel. Each of the primary and redundant receivers  110 ,  120  in  FIG. 1 , contains an image of a typical receiver  110 ,  120  signal path. The demodulator  140  and decoder  150  are well known in the art and defined in literature. The receiver system  100  may utilize known demodulators  140  and decoders  150 , or those specially designed for the receiver system  100 . The Selectivity and Down-Converter (SDC) component  130  and Transfer Media component  160  shall be explained in more detail in the following paragraphs. 
     The SDC component  130  acts as the interface to the antenna  115  infrastructure and provides multiple access support for the desired multiplexing scheme implemented throughout the wireless network. This SDC component  130 , along with the antenna infrastructure, provides the physical media to acquire the wireless signal. Once an RF signal is obtained, circuitry or firmware in the SDC component  130  provide the necessary filtering to isolate the desired spectral content of the signal, and down-convert or realign the signal to the desired frequency location for acquisition and demodulation. The signal conditioning is not restricted to either the analog or digital domains and may span portions of both domains to isolate the desire signal. 
     After the desired signal is acquired by the SDC component  130 , it is processed with a demodulator  140  to obtain the information contained within the desired signal. This information is decoded by the decoder  150  and the desired data is obtained by the receiver  110 ,  120 . This desired data is passed to a transfer media component  160  that organizes or encodes the data into a defined format. This formatted data is then sent to a data terminal component  170  for processing. It should be noted that the data terminal component  170  includes a storage medium and a processor, wherein the storage medium includes a set of executable code including instructions to operate the above-described method of the primary receiver  110  and the redundant receivers  120 . The set of executable code stored in the storage medium of the data terminal component  170  is executed by the processor, thus effectuating the operation of the receiver system  100 . It should further be noted that alternative embodiments may include such hardware components in the primary receiver  110 , the redundant receivers  120 , or in other locations in the receiver system  100 . 
     In the receiver system  100  utilizing redundant reception, at least two independent instances of the single reception path, as described in the preceding paragraphs are implemented. Each path includes a diverse antenna  115  input, and SDC component  130 , a demodulator  140 , a decoder  150  and a transfer media component  160 . The steams of transferred data are sent to a common data terminal component  170 . 
     The Data Terminal Component  170  will merge data paths from the primary and redundant receivers  110 ,  120  into a single data stream representing the information from the transmitting device (not shown). The method of combining this information can include several schemes to ensure that the best result is obtained. 
     Referring to  FIG. 4 , transferred data shall preferably reside in an encoded transfer data packet  400  format, which includes at a minimum a frame ID  410 , ECC  430  and source  440  location. These packets  400  can be tagged  450  by the decoder  150  ( FIG. 1 ) as good packets when no errors in the data  420  or no uncorrected data  420  errors occur, or tagged  450  as bad packets when uncorrected data  420  error causing loss of data is present. The transfer data packet  400  includes a frame ID  410  that is used to identify the data  420 , and time stamp the data  420  for each data packet  400  frame. Referring to  FIG. 1  simultaneously, when the data  420  is received in any of the receivers  110 ,  120 , and is demodulated by the demodulator  140  and decoded in the decoder  150 , the results of the information from the decoder  150  is the data packet  400 . The ECC  430  determines whether the data is correct, and if it is correct, then the tag  450  indicates that that particular transfer data packet  400  is a good data transfer packet  400 . The source  440  indicates where the transfer data packet  400  came from, that is, whether it came from the primary receiver  110  or from any one of the redundant receivers  120 . 
     Referring now to  FIG. 5 , the data terminal component  170  ( FIG. 1 ) sorts good packets  400  ( FIG. 4 ) in a sequential manner to reconstruct a data stream  500  and concatenate known good packets  400  together to form a composite data stream  530 . The composite data stream  530  could contain good packets  400  from any receiver  110 ,  120 , whether it was a primary receiver  110  or a redundant receiver  120 , dedicated to the reception of the desire signal. Still referring to  FIG. 5 , a primary receiver data stream  510  and a redundant receiver data stream  520  are aligned as shown. These two receiver data streams  510 ,  520  are aligned by frame ID, that is, frame n  540  is aligned as are frames n+1, n+2, n+3, and n+4,  540 ,  550 - 580 . The composite data stream  520  illustrates a composite of the two receiver data streams  510 ,  520 , including a data packet with a good tag for each frame ID. This composite data stream  530  is constructed by comparing the data packets from the primary receiver data stream  510  to the redundant receiver data stream  520  for each frame. For example, comparing the frame n  540  data packets, it is clear that both the primary receiver data stream  510  and the redundant receiver data stream  520  both include a “good” packet. Accordingly, the system may be preset to use the packet from the primary receiver data stream  510  in such cases. In frame n+1  550 , the primary receiver data stream  510  has a good tag, while the redundant receiver data stream  520  has a bad tag. In such a case, the data terminal component  170  would choose the packet from the primary receiver data stream  510  for the composite data stream  530 . In frame n+3  570 , the redundant receiver data stream  520  is the only good data packet, and therefore this packet is included in the composite data stream  530 . When the system includes many redundant receiver data streams  520 , then the data terminal component  170  will have a set of rules that determines which redundant receiver data stream  520  having a “good” tag will contribute to the composite data stream  530  when the primary receiver data stream  510  has a bad packet. 
     Referring now to  FIG. 6 , a method  600  of the present application is illustrated. In step  610 , a site survey is conducted on the physical area to determine an optimum wireless infrastructure configuration. Such site survey methods are well known in the art, and will allow the user of the wireless monitoring system to properly place the antenna  115  and receivers  110 ,  120  ( FIG. 1 ) to ensure coverage for the entire monitored area. In step  620 , the plurality of antenna  115  and receivers  110 ,  120  are configured in the wireless monitoring system according to the findings of the site survey. In step  630 , a physiological signal is acquired in each of the plurality of receivers  110 ,  120 , wherein the plurality of receivers  110 ,  120  each include an antenna  115  and an SDC module  130  for acquiring such signal. In step  640 , the acquired signal is processed into a plurality of transfer data packets in each of a plurality of receivers  110 ,  120 . In step  640 , the signal is demodulated, and decoded in the plurality of receivers  110 ,  120 . The decoder tags each of the plurality of transfer data packets with a “good” or “bad” tag depending on the quality of the acquired signal. The threshold for tagging each of the transfer data packets is predetermined by the user of the system and set accordingly. It is contemplated that the threshold for rating the quality of any given physiological signal as “good” or “bad” is highly dependent upon the type of physiological signal being processed. 
     Still referring to  FIG. 6 , the plurality of transfer data packets from each of the plurality of receivers  110 ,  120  is sent to a data terminal component  170 . Here, the plurality of transferred data packets from each of the plurality of receivers  110 ,  120  is merged into a composite data stream. The transfer packets are merged by aligning each of the plurality of data packets for each of the plurality of receivers  110 ,  120  in sequential order by frame ID, and choosing a “good” data transfer packet from one of the receivers  110 ,  120  for each data packet  400  corresponding to a specific frame ID. When two or more of the transfer data packets for any frame ID are labeled as “good”, a predetermined rule set will be used to select which transfer data packet to use in the composite data stream. As an example, if all of the transfer data packets have a “good” tag then the rule set may indicate that the data transfer packet from the primary receiver  110  should be utilized. The remainder of the plurality of receivers  110 ,  120  may be ordered accordingly. By way of second example, there may be a proximity transmitting device that issued the signal, that may set the order from which “good” transfer data packets should be taken. It should be noted that any number of methods or rules for selecting one of a plurality of “good” transfer data packets may be utilized. 
     In an alternate embodiment, the data  420  inside the packets  400  are evaluated bit-by-bit. In this embodiment, the application would perform a difference on the data packets  420  and tag  450  in the packets  400  that were different, and then reconstruct combinations of different permutations of the stream to search for an ECC  430  match. 
     Thus, by provisioning at least two receivers  110 ,  120 , in a topology that allows each receiver  110 ,  120  to acquire wireless communication signals simultaneously through different diverse antenna  115  paths, system reliability is improved and system susceptibility to data corruption or loss of data due to signal fading is reduced. The technical advantages focus on improving the reliability of the wireless communication system. Redundant monitoring reduces the probability that a signal fade on any antenna field results in the loss of data or data dropout in the wireless system. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.