System and method of enhanced quality of service of wireless communication based on redundant signal reception on two or more antenna diversity inputs

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.

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.

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 toFIG. 1, redundant coverage in the receiver system100will involve signal reception from a primary receiver110and at least one redundant receiver120. 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 receiver110or the redundant receiver120, to a data terminal component170for reconstruction. In this embodiment, the data terminal component170is not required to be the final destination of the received data. The primary and redundant receivers110,120offer the same performance characteristics, where the fundamental differences in reception results from antenna field diversity.

The receiver system100inFIG. 1includes antennas115in each of the receivers110,120that receive communication from the overall wireless system (not shown). These antennas115are deployed as spatially diverse antenna fields located across the provisioned service area of the wireless system. The location of each antenna115is based on specific design rules and results from a site survey. Because each antenna115is installed in a different location, the signal at each antenna115represents a unique realization of the wireless signal at any point in time. However, it should also be noted that any of the plurality of primary110and/or redundant receivers120may be implemented in a single hardware component.

Configuring antennas115in 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 receivers110, and120, which can be referred to as multipath situations or signals. When these multipath signals are combined at the aperture of the antenna115, 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 graph200inFIG. 2. This graph200shows 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 graph200illustrates the original signal230and the delay signal240graphically, with a signal amplitude220along the y axis of the multipath signal graph200, over a time period210on the x axis of the multipath signal graph200. This multipath signal graph200illustrates 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 graph300inFIG. 3. This graph300presents an example of a signal fade situation that may occur in a typical wireless system. Here the received signal power320differs as received by two different antennas, antenna signal (1)330and antenna signal (2)340, verses time310. The signal power fades335are shown to occur at different times and represent reception through independent antenna fields. If reception of signal antenna (1)330was used as the only signal for the receiver, as the signal faded335, and the receiver signal power320was 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 fade335and hand over reception to an alternate antenna.

Still referring toFIG. 3, in situations where fading is gradual, an antenna-switching algorithm in the receiver may detect the fade335and facilitate hand over of reception to another antenna, thus, preventing any dropout or degradation in performance. However, when the fades335occur rapidly, the antenna switching might not be capable of detecting the fade event335before 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 toFIG. 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 receiver110,120to acquire the desired information as it was transmitted across a communication channel. Each of the primary and redundant receivers110,120inFIG. 1, contains an image of a typical receiver110,120signal path. The demodulator140and decoder150are well known in the art and defined in literature. The receiver system100may utilize known demodulators140and decoders150, or those specially designed for the receiver system100. The Selectivity and Down-Converter (SDC) component130and Transfer Media component160shall be explained in more detail in the following paragraphs.

The SDC component130acts as the interface to the antenna115infrastructure and provides multiple access support for the desired multiplexing scheme implemented throughout the wireless network. This SDC component130, 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 component130provide 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 component130, it is processed with a demodulator140to obtain the information contained within the desired signal. This information is decoded by the decoder150and the desired data is obtained by the receiver110,120. This desired data is passed to a transfer media component160that organizes or encodes the data into a defined format. This formatted data is then sent to a data terminal component170for processing. It should be noted that the data terminal component170includes 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 receiver110and the redundant receivers120. The set of executable code stored in the storage medium of the data terminal component170is executed by the processor, thus effectuating the operation of the receiver system100. It should further be noted that alternative embodiments may include such hardware components in the primary receiver110, the redundant receivers120, or in other locations in the receiver system100.

In the receiver system100utilizing 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 antenna115input, and SDC component130, a demodulator140, a decoder150and a transfer media component160. The steams of transferred data are sent to a common data terminal component170.

The Data Terminal Component170will merge data paths from the primary and redundant receivers110,120into 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 toFIG. 4, transferred data shall preferably reside in an encoded transfer data packet400format, which includes at a minimum a frame ID410, ECC430and source440location. These packets400can be tagged450by the decoder150(FIG. 1) as good packets when no errors in the data420or no uncorrected data420errors occur, or tagged450as bad packets when uncorrected data420error causing loss of data is present. The transfer data packet400includes a frame ID410that is used to identify the data420, and time stamp the data420for each data packet400frame. Referring toFIG. 1simultaneously, when the data420is received in any of the receivers110,120, and is demodulated by the demodulator140and decoded in the decoder150, the results of the information from the decoder150is the data packet400. The ECC430determines whether the data is correct, and if it is correct, then the tag450indicates that that particular transfer data packet400is a good data transfer packet400. The source440indicates where the transfer data packet400came from, that is, whether it came from the primary receiver110or from any one of the redundant receivers120.

Referring now toFIG. 5, the data terminal component170(FIG. 1) sorts good packets400(FIG. 4) in a sequential manner to reconstruct a data stream500and concatenate known good packets400together to form a composite data stream530. The composite data stream530could contain good packets400from any receiver110,120, whether it was a primary receiver110or a redundant receiver120, dedicated to the reception of the desire signal. Still referring toFIG. 5, a primary receiver data stream510and a redundant receiver data stream520are aligned as shown. These two receiver data streams510,520are aligned by frame ID, that is, frame n540is aligned as are frames n+1, n+2, n+3, and n+4,540,550-580. The composite data stream520illustrates a composite of the two receiver data streams510,520, including a data packet with a good tag for each frame ID. This composite data stream530is constructed by comparing the data packets from the primary receiver data stream510to the redundant receiver data stream520for each frame. For example, comparing the frame n540data packets, it is clear that both the primary receiver data stream510and the redundant receiver data stream520both include a “good” packet. Accordingly, the system may be preset to use the packet from the primary receiver data stream510in such cases. In frame n+1550, the primary receiver data stream510has a good tag, while the redundant receiver data stream520has a bad tag. In such a case, the data terminal component170would choose the packet from the primary receiver data stream510for the composite data stream530. In frame n+3570, the redundant receiver data stream520is the only good data packet, and therefore this packet is included in the composite data stream530. When the system includes many redundant receiver data streams520, then the data terminal component170will have a set of rules that determines which redundant receiver data stream520having a “good” tag will contribute to the composite data stream530when the primary receiver data stream510has a bad packet.

Referring now toFIG. 6, a method600of the present application is illustrated. In step610, 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 antenna115and receivers110,120(FIG. 1) to ensure coverage for the entire monitored area. In step620, the plurality of antenna115and receivers110,120are configured in the wireless monitoring system according to the findings of the site survey. In step630, a physiological signal is acquired in each of the plurality of receivers110,120, wherein the plurality of receivers110,120each include an antenna115and an SDC module130for acquiring such signal. In step640, the acquired signal is processed into a plurality of transfer data packets in each of a plurality of receivers110,120. In step640, the signal is demodulated, and decoded in the plurality of receivers110,120. 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 toFIG. 6, the plurality of transfer data packets from each of the plurality of receivers110,120is sent to a data terminal component170. Here, the plurality of transferred data packets from each of the plurality of receivers110,120is 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 receivers110,120in sequential order by frame ID, and choosing a “good” data transfer packet from one of the receivers110,120for each data packet400corresponding 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 receiver110should be utilized. The remainder of the plurality of receivers110,120may 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 data420inside the packets400are evaluated bit-by-bit. In this embodiment, the application would perform a difference on the data packets420and tag450in the packets400that were different, and then reconstruct combinations of different permutations of the stream to search for an ECC430match.

Thus, by provisioning at least two receivers110,120, in a topology that allows each receiver110,120to acquire wireless communication signals simultaneously through different diverse antenna115paths, 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.