Patent Publication Number: US-11665008-B2

Title: Ultra-low power mesh network

Description:
The present application is a continuation of patent application Ser. No. 16/918,342 filed Jul. 1, 2020, which is a continuation of patent application Ser. No. 15/811,690 filed Nov. 14, 2017, now issued as U.S. Pat. No. 10,742,429. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to stations and methods for providing low power connectivity in a mesh network. In particular, the invention provides ultra-low power connectivity for stations positioned in receiving range of each other. 
     BACKGROUND OF THE INVENTION 
     Prior art wireless systems such as 802.11 provide communications where a central node (an “access point”) is coupled to other stations using an “infrastructure mode”. This type of infrastructure system relies on the access point being powered continuously, and the power savings comes about by using, for example, access point beacon frames, where the access point periodically transmits beacon frames at expected times, such that the stations wake up at corresponding intervals of time and listen to beacon TDIM frames which indicate whether packets are available at that time of coming out of a sleep mode. The power consumption is thereby reduced by a factor equal to the small percentage of time the stations are awake compared to the beacon interval. This type of infrastructure works well where the access point is able to be powered by an external power source, and requires that the stations be clustered within receiving range of the access point.  FIG.  1    shows an example positioning of stations S1 through S8 and access point AP1. Typical attenuation of wireless signals is as follows (2× indicates a doubling of separation distance between stations): 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Line of Sight (LOS) loss 
                  6 dB/2x distance 
               
               
                   
                 Indoor LOS loss with multi-path 
                 12 dB/2x distance 
               
               
                   
                 loss per concrete floor traversal 
                 15 dB/floor + indoor 
               
               
                   
                   
                 LOS loss 
               
               
                   
                   
               
            
           
         
       
     
     Accordingly, if the network of  FIG.  1 A  were in open space without barriers and examined in plan view (positioned horizontally in open space), the loss from AP1 to S1 might be 61 dB, AP1 to S2 67 dB, and AP1 to S4 71 dB, whereas for the same dimensions, with  FIG.  1 A  examined as an elevation view with the lines representing concrete floors and including indoor multipath loss, the loss from AP1 to S1 would be 106 dB, from AP1 to S2 would be 157 dB, and from AP1 to S3 would be in excess of 200 dB. If the link budget is on the order of 140 dB, then most of the stations are out of range of the access point. 
     Another type of network is known as a mesh network, where the stations each communicate with each other as peers. For  FIG.  1 A , this type of network topology has S1 communicate with AP1 and S2, S2 to S1, S4, S5, and S3, etc. The mesh network has a different set of considerations and issues. One issue is that the network needs to find a route from each station to a gateway such as AP1, and another issue is that there is no centralized timing or transmission as infrastructure mode provides. 
     Both types of networks, infrastructure and mesh, require access to the internet at large, which is provided by a function known as a gateway router. This functionality is typically offered through an access point AP1 of  FIG.  1 A , or it may alternatively be offered through a mesh station having connectivity to a gateway router. 
     Battery powered systems utilize a finite amount of Joule stored energy, such that the Joule product of power*time may be conserved only by either reducing power or reducing the amount of time that power is drawn. When viewed from the perspective of a fixed Joule source and a desired battery lifetime for a given battery size, the problem reduces to one of duty cycle and latency. In the following illustrations of prior art, a fixed source of two AAA batteries is used, which provides 1000 mAh @3V. Accordingly, for 10 year operation form this storage source, the average current draw is maximum 10 uA at 3 V, which will now be used to compare the performance of various prior art systems. 
     In the prior art, battery powered network nodes typically use Bluetooth (at a typical 6 mA listen current at 3V) which offers lower power consumption than 802.11 WLAN (at a typical 60 mA listen current at 3V). For a 10 year battery life using two AAA batteries, and the best case of synchronous wakeup intervals across all stations, an average current of 10 uA could be accomplished in Bluetooth (from 5 mA continuous current) by power-cycling the Bluetooth device on for periodic and synchronized listen intervals across all stations, with a duty cycle of 1/500 and a 1 ms on (listen) time. The corresponding approach could be used in WiFi with a duty cycle of 1/6000 and a 1 ms on (listen) time, both would satisfy the 10 uA average current requirement specified. The 10 year 1 AH 3V constraint using two AA cells is used as a uniform baseline example for understanding the invention and its benefits, other power source capacities can be computed using those metrics in the same manner. 
     For a mesh of 4 stations, where one station has to check with each of the four other stations, each check requiring a 1 ms event wakeup event, the time for each hop is 1 ms*500*4=2s for Bluetooth and 1 ms*6000*4=24s for WiFi. Accordingly, just 10 hops through a mesh network has a latency of 20s (˜4 min) for Bluetooth and 4 minutes for WiFi, which are unacceptable for most purposes. 
     With four edge nodes (reducing throughput by 4), and where WiFi data throughput is 10 Mbps peak (at 1/6000 duty cycle) and Bluetooth throughput is 250 Kbps (at 1/500 duty cycle), the above examples provide per-day download data of 18 MB for WiFi and 5.4 MB for Bluetooth, which would restrict these uses to very low data transfer applications. 
     Another problem of the prior art is that for dynamically changing networks, a significant amount of power is consumed with RF advertising, in the case of Bluetooth (Bluetooth Low Energy, known as BLE), where the slave device has an advertising interval and the master device has a scan window and scan interval. As the below table shows, short Bluetooth connection times require the advertising window and scan interval both be short, which greatly increases battery drain. For Bluetooth Long Range (BLR), the problem is exacerbated over BLE by the increased BLR transmit frames and requirement for low duty cycle. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
                   
               
               
                   
                 Advertising 
                 Scan 
                 Scan 
                 Avg 
                 99% 
               
               
                   
                 interval 
                 Window 
                 Interval 
                 connection 
                 connection 
               
               
                   
                 (ms) 
                 (ms) 
                 (ms) 
                 time (s) 
                 time (s) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 30 
                 30 
                 30 
                 .02 
                 0.04 
               
               
                   
                 60 
                 30 
                 30 
                 .03 
                 0.07 
               
               
                   
                 100 
                 30 
                 30 
                 .06 
                 0.11 
               
               
                   
                 30 
                 11.25 
                 1280 
                 2.71 
                 12.8 
               
               
                   
                 60 
                 11.25 
                 1280 
                 5.54 
                 23.04 
               
               
                   
                 100 
                 11.25 
                 1280 
                 8.92 
                 35.84 
               
               
                   
                 1280 
                 30 
                 30 
                 0.67 
                 1.37 
               
               
                   
                 1280 
                 11.25 
                 1280 
                 162.5 
                 323.84 
               
               
                   
                   
               
            
           
         
       
     
     It is desired to provide an apparatus and method for ultra-low power mesh networks which provides bidirectional connectivity from a plurality of peer stations to a gateway router at a higher data rate than the prior art provides. 
     OBJECTS OF THE INVENTION 
     A first object of the invention is a mesh device and method for receiving packets, the mesh device having a wakeup receiver and a mesh receiver, the wakeup receiver receiving wakeup frames optionally comprising a first wakeup segment and a second wakeup segment followed by an optional command part, the wakeup receiver comparing the wakeup segments against respective patterns, and when the wakeup segments match the respective patterns, optionally examining the command part, the mesh receiver thereafter waking up and accepting WLAN packets, the mesh receiver thereafter receiving packets and placing them into a queue, thereafter the mesh receiver sending a wakeup sequence directed to a remote node of the mesh based on a routing destination, the node transmitting the packets from the receive queue, thereafter going back into a sleep mode upon acknowledgement of receipt by the remote node. 
     A second object of the invention is a mesh device and method for transmitting packets, the mesh device having a transmitter in a wakeup transmit mode which transmits an entire packet to form each 1 value and not transmitting for an equal interval of time to form a 0 value during a wakeup transmit interval to send a sequence of 1 and 0 values forming a wakeup sequence, after a remote mesh station has awaken in response to the wakeup sequence and replied with an acknowledgement, thereafter the transmitter operative in a mesh transmit mode to send WLAN packets and going back to sleep when completed. 
     A third object of the invention is an apparatus and method for ultra-low power communications operative on a mesh device having a wakeup transmitter, the wakeup transmitter periodically transmitting a wakeup sequence of 1s and 0s, where each 1 is formed from the transmission of an entire WLAN packet, and each 0 is formed by non-transmission during an interval corresponding to the duration of a WLAN packet, the remote station acknowledging the wakeup sequence by sending an acknowledgement packet. 
     A fourth object of the invention is an apparatus and method for sending a wakeup sequence to a remote station using a WLAN transmitter, the WLAN transmitter sending a first sequence of is and 0s, each 1 formed from an entire WLAN packet or RF keying and each 0 formed by an interval of non-transmission having a duration equal to the duration of a WLAN packet, the WLAN thereafter sending a second sequence of 1s and 0s, each 1 formed from an entire WLAN packet or RF keying which is shorter than a WLAN packet or RF keying of the first sequence and each 0 formed by an interval of non-transmission equal to the duration of a second sequence WLAN packet. 
     A fifth object of the invention is an apparatus and method for ultra-low power communications operative on a mesh device having a wakeup receiver, the wakeup receiver operative continuously and operative to detect a first pattern of is and 0s formed from entire WLAN packets followed by a second pattern of is and 0s formed from entire WLAN packets of shorter duration than the WLAN packets of the first pattern, the wake-up receiver operative to listen to the first sequence and second sequence, if the first sequence and second sequence match respective template patterns, the wakeup receiver next receiving a unicast or broadcast address and an optional command containing a channel assignment or protocol assignment for a receiving mesh node. 
     SUMMARY OF THE INVENTION 
     A mesh network node known as “Wake-Fi™” has a transmitter operative in a wakeup mode and a mesh transmit mode. In a wakeup transmit mode, the node periodically transmits a wakeup sequence to surrounding mesh network nodes with is either node specific (unicast) or universal (broadcast), the wakeup sequence operative to enable at least one surrounding mesh network node. The wakeup sequence may also include an optional command, such as a mesh protocol assignment, which may direct subsequent communications to be using one of the 802.11 WLAN protocols, Bluetooth Low Energy protocol, Bluetooth Long Range protocol, Zigbee protocol, or contain a channel hopping assignment, frequency assignment or channel assignment for use in subsequent communications. The node transmits the wakeup pattern as a sequence of a series of 1 and 0 values using a low power RF transmitter to form the wakeup sequence, each 1 formed from an entire wireless packet of fixed length, with a single packet representing a 1 value, and the absence of transmission representing a 0 value and of equal duration as the packet of the 1 value. The RF generated for the wakeup sequence need not be precision frequency or formed from a packet, but simply RF that can be mixed, rectified and detected, such as RF from a ring oscillator or other simple low power method. The wakeup sequence optionally has a first unique sequence which is transmitted at a low data rate, and a second sequence which is transmitted at a comparatively faster data rate. Alternatively, the wakeup sequence may be a unique sequence, matching the wakeup pattern for at least one surrounding node. Following the acknowledgement of the wakeup pattern with a wireless packet, the transmitter may thereafter send WLAN packets for propagation through the mesh network. 
     Each mesh network node also has an ultra-low power receiver which is operative to receive the wakeup sequence formed from entire packets transmitted by a different mesh node. Upon receipt of the wakeup sequence and any optional commands which follow, the node wakes up and transmits an acknowledgement as a WLAN packet in a mesh transmit mode. Upon receiving the matching wakeup pattern, mesh network node powers up a fully-featured receiver and receives and buffers any packets which follow, acknowledging reception and powering down until a subsequent transmit event for sending the packets through the mesh network. 
     In an advertising mode, each mesh network node sends out a short periodic advertisement, which all surrounding stations receive and use to update their connectivity table to indicate the respective power level of the received advertisement. 
     In a communications mode, when the mesh network node has data to transmit or forward, the mesh node determines which mesh node is along the best path, and best receiver, and optionally selects a mesh station to equalize power consumption or resource utilization using a table of nearby stations which indicate for each nearby station a signal strength, hop count to a gateway if applicable, battery state of charge (to ensure uniform draw on all of the devices in the mesh) and causes the wakeup transmitter to send a wakeup frame containing the address or wakeup pattern of the next station. When the mesh network node receives an acknowledgement to the wakeup sequence from the remote station (which was sent using a high speed protocol such as WLAN, Bluetooth, Zigbee), the mesh network node transmits one or more high speed protocol (WLAN, Bluetooth, Zigbee) frames to the destination station. 
     Either periodically with the transmission of advertising sequence patterns (received by all stations), or alternatively when the mesh node wakeup receiver receives a wakeup sequence from an adjacent station, the wakeup receiver checks to see that the transmitting station is in a current list of stations, and either adds the adjacent station to the list of stations or updates an existing entry for that adjacent station, with the list of stations organized by a remote station identifier. Optionally, the transmitting station includes a metric indicating its distance from a gateway, its state of charge (SOC), and any other information which is used in the node&#39;s own advertisements to other nodes for its distance to the gateway and SOC information for computing route metrics, for the case of the gateway distance, by adding one to the number of hops to the gateway. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  shows the positions of a gateway station and a plurality of stations in either a plan view without barriers, or alternatively an elevation view of stations in a building. 
         FIG.  1 B  shows block diagram of a plurality of stations in a mesh network. 
         FIGS.  2 A and  2 B  show the list of stations maintained by each of the nodes in  FIG.  1 B . 
         FIG.  3    shows a block diagram of a mesh node. 
         FIG.  4    shows waveforms for the sequence of transmissions by a wake-up transmitter of a node of  FIG.  3   . 
         FIGS.  4 A,  4 B, and  4 C  show waveforms for alternate wakeup transmit sequences. 
         FIG.  5 A  shows a time sequence diagram for a first mesh station transmitting to a second mesh station. 
         FIG.  5 B  shows a time sequence for data passing through the mesh network of  FIG.  1 B . 
         FIGS.  6 A,  6 B,  6 C,  6 D,  6 E,  6 F, and  6 G  show timing diagrams for the movement of data through three stations. 
         FIG.  7    shows a flowchart for a wakeup receiver process. 
         FIG.  8    shows a flowchart for a wakeup transmitter process. 
         FIG.  9    shows a flowchart for a mesh receiver process. 
         FIG.  10 A  shows a perspective view of an arrangement of mesh nodes for package delivery and tracking. 
         FIG.  10 A- 1    shows a plan view of an example residence of  FIG.  10 A . 
         FIG.  10 B  shows a perspective view of a residential neighborhood with consumer tags for monitoring and tracking items. 
         FIG.  10 C  shows a perspective view of a residential neighborhood with infrastructure tags for smart city monitoring of utilities and residential items. 
         FIG.  10 D  shows a plan view of a residence in a smart city configuration of the invention. 
         FIG.  10 E  shows a plan view of several residences in a mesh network. 
         FIG.  11 A  shows a timing diagram for an example hierarchical first and second wakeup sequence. 
         FIG.  11 B  shows a table of false alarm rates for the first and second wakeup sequence of  FIG.  11 A . 
         FIG.  12    shows an example block diagram for a wake-up receiver according to an embodiment of the present invention. 
         FIG.  12 A  shows a block diagram of a secure wakeup pattern generator for use in a transmitter and receiver. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG.  1 B  shows an example mesh network formed from mesh devices of the present invention. Each of the mesh stations M1  102 , M2  104 , M3  106 , M4  108 , M5  110 , M6  112 , M7  114 , M8  116  is shown as  300  of  FIG.  3   , which includes wakeup receive processor  304  for waking up the mesh receive processor  308  from an RF sequence, and transmit processor  302 , which is operative in a wakeup transmit mode for sending a wakeup sequence formed from keyed RF patterns (or alternatively from entire WLAN packets) as a sequence of “1” values for an entire packet or RF duration or “0” when not transmitting for an equal interval of time, sending this sequence to surrounding mesh stations as RF. In a mesh transmit mode, the transmit processor  302  may transmit ACK and data packets as IEEE 802.11ac, IEEE 802.11n, IEEE 802.11g, or any IEEE 802.11 frame format, or it may transmit ACK and data packets as Zigbee, or it may transmit ack and data packets as Bluetooth packets, either as BLE or BLR packets. 
     Each station maintains a list of adjacent stations as entries, each entry shown with the associated link for reference, the entry including a remote station identifier, a signal strength for that remote station, a State of Charge (SOC) indicating the remaining battery life, and a gateway path number (GPn) showing how many hops to a remote gateway. From these entries, a metric may be formed which indicates a best routing path which also ensures that all of the mesh station batteries are uniformly depleted over the life of the mesh stations.  FIGS.  2 A and  2 B  show an example list of entries for each station M1, M2, M3, M4, M5, M6, M7, and M8. Upon receipt of a wakeup frame from an adjacent mesh station, the receiving station wakes up, optionally sets itself to a particular wireless protocol (802.11, Zigbee, Bluetooth) on a specified frequency channel or temporal channel, sends an ACK packet to the wakeup transmitting station using the selected protocol and channel which optionally accompanied the wakeup sequence, enables its mesh receiver for the selected protocol and channel, receives the transmitted frames from the sending mesh station, places them into a queue, and either goes back to sleep, or sends the wake-up sequence directed to the intended next mesh station according to routing instructions it derives from its own set of route tables and any address information in the packets it receives. 
       FIG.  4    shows a timing diagram for a mesh transmit protocol according to an example of the invention. Each mesh device M1 through M8 operates autonomously from any other mesh device. As previously described for  FIG.  3   , each mesh device has a wakeup transmitter for sending a wakeup pattern to surrounding mesh devices, the wakeup message comprising a wakeup sequence of 1s and 0s formed by a packet and a packet gap, respectively, or keyed RF, either one of which is optionally followed by a command for establishing protocol, channel, and any other parameters for the communications which follow using the mesh transmitter and mesh receiver, starting with the mesh transmitter sending an ACK to the transmitting station in response to its wakeup sequence. 
     At a time when a mesh device has data to transmit to another station, the mesh device wakeup transmitter sends a wakeup sequence, using an entire packet of length n to form a “1” value and not transmitting anything for an equal duration of time to form a “0” value. By sending a sequence of packets (“1” value) and gaps (“0” value), the wakeup sequence may be sent, which may optionally be only a wakeup sequence universal to all mesh stations (for example so that each station can establish or refresh its table of neighbor stations), or the wakeup sequence may contain a first segment and second segment of different data rates, or a command may optionally follow the wakeup sequence that establishes the protocol and channels in use thereafter, as before. 
     In a hierarchical wakeup sequence, the wakeup sequence may comprise two or more wakeup sequences having different bit interval timings, for example the wakeup sequence may comprise a low rate first wakeup sequence followed by a higher rate wakeup sequence, each formed from a sequence of packets and gaps as previously described, each 1 or 0 of a subsequent wakeup sequence having a 1 or 0 bit duration t of t/2, t/4, t/8, or t/16 compared to the 1 or 0 of a previous sequence. For example, the wakeup sequence could be 2 ms overall, as 8 bits in 1 ms followed by 64 bits in 1 ms. In another example of the hierarchical wakeup sequence, the first wakeup sequence may be a universal sequence of is and 0s for the first wakeup segment followed by a higher rate second wakeup sequence where the second wakeup sequence includes an address specific to a particular destination mesh station. The advantage of the hierarchical wakeup sequence is that a receiving mesh device may sample at a comparatively low rate until it senses that a mesh station wishes to transmit, thereafter examining the second wakeup segment at a higher sampling rate to determine whether its address is specified in the second wakeup sequence and that it should awaken. The hierarchical approach for wakeup sequences has power savings advantages over operating at a high sample rate at all times. The wakeup sequences may be transmitted by a mesh station at regular intervals, such as once per second or once per 0.1 second, or adjusted dynamically to match the rate of traffic or utilization. 
       FIG.  11 A  shows an example hierarchical wakeup sequence where, following channel noise  1107 , a first wakeup sequence is received which is 1 ms long, comprised of 8 bits transmitted at a rate 125 us per bit and with an first sequence false alarm rate (FAR) of 10% over the 8 bit sequence, meaning that the incoming pattern is cross-correlated to form a cross-correlation sum which is compared to a threshold corr_threshold. In this example, the first 8 bit wakeup sequence  1108  may be cross-correlated with a universal 8 bit wakeup pattern, the cross correlation generating a +1 for each bit match and a 0 for each mismatch, with the result at the end of the cross-correlation compared to the corr_threshold to generate a trigger which tells the wakeup processor to continue sampling the second 1 ms, but using an 8× higher sample rate (and accordingly higher power consumption). The initial sample rate set to 125 us has advantageously low current draw, whereas the higher sample rate and higher current draw is only incurred when the first sequence cross-correlation threshold is exceeded, with the threshold set to an example 10% FAR (rate of false detection of first wakeup sequence). The threshold corr_threshold may be varied according to desired system performance to higher or lower false alarm rates. If the first wakeup sequence does not match the pattern stored by the device, the device continues to sample at the 1 ms rate until it does find a match. The current consumption during the time searching for the matching 8 bit sequence has an advantageously low current consumption of just 1 uA, and the first 8 bit sequence  1108  may be a common pattern recognized by all devices. The second sequence  1110  is also 1 ms in duration, transmitted as 64 bits at 15.6 us per bit, resulting in 8× the power consumption during the second wakeup sequence at 8 uA. If the second wakeup sequence does not match the wakeup pattern (which may include the device-specific address or multi-cast address), the device returns to the lower sample rate of the first wakeup sequence search. Accordingly, the 64 bits of the second sequence have a low false alarm rate of 10 −8 , ensuring that when only 20% of the wakeup sequence (first and second sequences) are directed to a particular station the current consumption for that station is 1 uA 80% of the time and 8 uA for 20% of the time, resulting in an average current of 2.6 uA. This is a significant improvement over the case where a single wakeup pattern of 64 bits is used, resulting in a current draw of 8 uA for the wakeup sequence. In one example hierarchical embodiment, the first wakeup sequence is 8 bits in 1 ms, and does not include a pseudo-random sequence as described in U.S. Pat. No. 9,477,292, which is incorporated in its entirety by reference. In the example embodiment, the second wakeup sequence is 64 bits in length and at least part of the second wakeup sequence is time encrypted such that a sequence of possible next pseudo-random sequences are autocorrelated for wakeup. Additionally, the second wakeup sequence may include a unicast address for a single device, a broadcast address for several devices, and the second wakeup sequence may be followed by additional commands including a channel assignment or protocol assignment. 
     As the incoming wakeup pattern bit rate is very low, the wakeup RF receiver may be powered on and off at a rate of the bit rate of the bit sequence being sampled. For the present example of 8 bits in 1 ms followed by 64 bits in 1 ms, the receiver may repetitively power on and off at a rate of 8 Khz during the first interval and 64 Khz during the second interval, each sample used in forming a running cross-correlation result with the wakeup-pattern, as described in U.S. Pat. No. 9,477,292. 
     On the wake-up pattern transmission as it relates to prior art Access Points (AP) and other equipment which predates the present invention, a particular advantage of the wakeup-transmitter mode  302  is that any existing prior art WiFi device which is able to be firmware upgraded can form wake-up packets according to the present invention, since WLAN packets with arbitrary data contents can be formed into a wakeup sequence easily, with the packet length selected to form the “1” pattern and non-transmission forming the “0” pattern of the first and second wakeup sequence, and both the mesh device and the prior art WiFi device are already fully capable of communication once the mesh device is awake using prior art WLAN methods and standards. In this manner, the prior art WLAN device can easily be firmware upgraded to transmit the wakeup sequence as a series of packets and packet gaps. 
     The waveform  402  of  FIG.  4    shows an example wakeup sequence, where the wakeup sequence is transmitted at regular intervals for mesh node advertisements, such as from  404  to  406 , from  408  to  410 , and from  412  to  414 , or on a demand basis when a node has data to transmit through the mesh. Alternatively, the wakeup transmissions may occur at an infrequent rate, and thereafter on a demand basis when data has been received which is to be forwarded to a subsequent mesh station. 
     An expanded view of a wakeup sequence  404  to  406  is shown in  FIG.  4 A  waveform  420 , where each “1” value  422  and  426 , for example, is formed by an entire WLAN packet (from preamble through CRC), and each “0” value  424  is formed by having the transmitter remain silent for an equal duration of time as the “1” value packet duration of time, with the “1” values and “0” values each having a uniform time length in each sequence, as was previously described. Waveform  420  shows a single wakeup sequence  434 , where the wakeup sequence is a unique address for a receiving station (for a unicast transmission) or is a common address shared by all stations (for a broadcast message). 
       FIG.  4 B  waveform  440  shows a hierarchical wake-up sequence embodiment, where the wakeup sequence  443  comprises a first wakeup sequence  442  followed by a higher rate second wakeup sequence  456 . Optional commands  458  may follow for protocol and channel selection, as previously described. 
       FIG.  4 C  shows another variation, where the wakeup sequence  469  may be identical for all mesh stations and followed optionally by a device address (unicast or broadcast)  478 , and also optionally include commands  480 . 
       FIG.  5 A  shows a timing diagram for mesh stations A  502  sending data to mesh station B  504  using a WLAN protocol and predefined channel assignments. Station A  502  starts by sending a wakeup sequence (1s and 0s as WLAN packet/silence from transmitter  302  of  FIG.  3   ) to surrounding stations. Station B has an address which corresponds to the particular wakeup sequence transmitted by station A  502 , and responds by waking up during interval  508 , activates its mesh transmitter for WLAN packets, and transmits an acknowledgment  510  to station A, which has also awoken to receive the acknowledgement as a WLAN packet. The mesh station  502  transmits packets  512 , which are acknowledged  514  by station B  504 , and station A goes back to sleep in a low-power mode, responding only to wakeup packets it may receive from surrounding stations where the wakeup packet is formed to include the address of STN A. 
       FIG.  5 B  shows a timing diagram for mesh communications, where the sequence of figure aA repeats for each event for station M8  520  transmitting packets to GW1  528  through the mesh. The sequence of wakeup sequence  530 , WLAN ACK  532 , WLAN data  534 , and WLAN ACK  536  complete the transmission from mesh station M8 to M5  522 . M5  522 , before or after sending ACK  536  to M8, sends a wakeup packet  538  to M2, which initiates the same WLAN ACK sequence of  540 , TX DATA  542 , and WLAN ACK  544  in transferring from M5 to M2. The transfer from M2 to M1 similarly occurs starting with wakeup sequence  546 , and mesh transmit  550  sends high speed data from M2 to M1 using any of the protocols as described. Data from mesh station M1  526  to gateway  528  is accomplished in the final step where the gateway  528  may be awaken with packet  554 , which is acknowledged as a WLAN packet  556 , and the data is transmitted  558  and acknowledged  560 . 
       FIG.  6 A to  6 G  shows a time sequence corresponding to the movement of data from M8 to M5 and from M5 to M2 of  FIG.  5 B . Waveform  602  shows the wakeup sequence sent to M5 from  620  to  622  and received by M5 as waveform  604  showing the receive event from  624  to  626  of the 1 and 0 wakeup sequence, which is acked from time  628  to  630 , followed by data transmission from  632  to  634 , which the remote station acks from  646  to  648 , which initiates station M5 waking M2 from  640 - 642 , ending the canonical cycle of wakeup, ack, data transmission, ack, and next station wakeup shown by the transactions of  601  (vertical axis). 
     In one example, the mesh network may be configured for operation as a local mesh (such as the package delivery example of  FIG.  10 A  where the mesh station of the package is coupled over a short distance to a nearby warehouse access point  1027 , drone mesh station, delivery truck mesh station or residence mesh station. In another example, the mesh network may be configured for longer long range connections, such as when used as a neighborhood mesh of  FIG.  10 B  or smart city of  10 C. 
     For a local mesh, the wakeup receiver requires receive sensitivities similar to those used in WLAN IEEE Standard 802.11n, 802.11ac, ZigBee or Bluetooth, with receiver sensitivity for an approximate 100-110 dB link budget, which implies approximately 10-20 dBm transmit power and approximately −85 to −95 dBm receiver sensitivity. The distance between stations in each hop of a local mesh is typically 30 m-200 m depending on path obstacles. In a neighborhood mesh with longer link distances, greater sensitivities similar to WLAN IEEE 802.11ah or Bluetooth Long Range protocol are used of approximately 125-140 dB link budget, translating into a transmit power of 10-25 dBm and −105 to −120 dBm receiver sensitivity. Using these metrics, each hop in neighborhood mesh can reach 200 m to 2 km typically, depending on the multi-path reflection and path obstacles. 
     Additionally, for a neighborhood mesh, the receiver sensitivity requirement is greater than the local mesh configuration. The increased receiver sensitivity for the neighborhood mesh is achieved by using a receiver with lower noise figure, greater antenna gain, and narrower receiver bandwidth of approximately 100 KHz to 400 KHz whereas the wakeup receiver operating on a local mesh configuration can have relaxed receive bandwidth of approximately 2 MHz to 10 MHz. For mesh communications, the receive bandwidth is typically achieved by mixing the received RF to an intermediate frequency (IF) and filtering that frequency, then baseband converting the IF. In the case of the wakeup receiver, it is sufficient for the wakeup receiver to convert the incoming RF to an IF that is approximately 2 Mhz to 10 Mhz offset from the carrier frequency for local mesh communications, or 500 Hkz for neighborhood mesh communications, where the carrier is typically 2.4 Ghz or 5 Ghz for 802.11. In either method, the output of the IF mixer is filtered to the bandwidths described and envelope detected such as with a diode or baseband mixer and filter. 
       FIG.  12    shows an example block diagram for a wakeup receiver  1204  according to the present invention. Wireless wakeup sequences are received on antenna  1202  according to keyed on/off patterns of RF power, which are received and amplified  1206  and applied to mixer  1208 , which mixes with a local oscillator which is offset by a frequency such as approximately 100 Khz-400 Khz for a neighborhood (long range) receiver, or 2 Mhz-10 Mhz for a local (short range) receiver, and is filtered  1212 , envelope detected  1214 , threshold detected to produce and store a binary pattern, which is correlated and accumulated  1218 - 1 . The correlator will produce a peak accumulated value at the point where the incoming wakeup sequence from threshold detector  1216  matches the wakeup pattern stored in key  1220 - 1 , with an example 8 Khz sample rate, which will trigger threshold detector  1222 - 1 , signaling to the controller to start sampling at the rate of the second wakeup sequence (64 Khz for 64 bits in 1 ms). As an additional power savings, the processing circuitry  1206 ,  1208 ,  1210 ,  1212 ,  1214 ,  1216  are powered up only long enough to take a sample to provide to the correlator  1218 - 1 , each component powered up a settling time prior to the sample time. It should also be noted that because the IF filter frequency  1212  has a longer response time for neighborhood mesh applications than local mesh applications, the IF filter is programmed by the controller  1226  accordingly, and the power-on duty cycle  1228  is slightly increased to compensate for the longer settling time required in neighborhood mesh wakeup configuration than local mesh wakeup configurations. In one example of the invention, the sample rate (and power-up rate of the processing elements of  FIG.  12   ) is the same as the bit rate. In another example of the invention, the samples are taken as “even” samples at 1× the wakeup pattern bit rate and as “odd” samples at 1× the wakeup pattern bit rate, shifted 180 degrees to the midpoint of the “even” samples. In this manner, the problem of sampling transitions is avoided. 
     For a wakeup pattern which is secured by a random sequence derived from a time for secure wake-up sequences, multiple correlators and keys are used  1218 - 1 / 1220 - 1 ,  1218 - 2 / 1220 - 2 ,  1218 - 3 / 1220 - 3 , one for each possible key to cover the case of temporal boundary key changes.  FIG.  12 A  shows an example of key generation  1250  where each matching key is securely generated at both the transmitting station and each receiving mesh station. A root of trust  1252  secures that the shared public key  1254  is authentic, and public key  1254 , private key  1256  which is securely given to all stations during a commissioning event. The commissioning event may be the assignment of a hard-coded secret key burned into the device at time of manufacturing of all mesh station devices, or by using an assigned secret key at a configuration event. The public and private key, as well as a time clock  1258  are input to a one-way function  1260  which generates an output code from which it is difficult to extract the algorithm which produced it. The one-way function may be a hash, or it may be any function for which it is difficult to find an inverse function, thereby preventing the extraction of the private key or function for use in spoofing the network from knowledge gained by examination of the behavior of the one-way function  1260  or its output sequences. The output of function  1260  is used to update at least one of first key  1220 - 1 , second key  1220 - 2 , or third key  1220 - 3  used by the receive wake-up correlator. Typically, a transmitter will use a first time-varying key for unicast transmission, and a second time-varying key for multi-cast transmission, or a single key may be used with the unicast/multicast distinction provided by a follow-on field, as was described previously. The receiver keys  1220 - 1 ,  1220 - 2 , and  1220 - 3  are the wakeup sequence patterns used by the autocorrelator as described for  FIG.  12    and also used as the wakeup sequence sent by the wake-up transmitter. When the secure key changes because of a time increment, the transmitter protocol completes the current secure key transmission before changing to a different secure transmit key, so the incoming sequence of correlation is allowed to complete before the controller  1226  provides a new secure key, and it only need change one secure key at a time at each secure key update event. 
     Using the hierarchical first wakeup pattern and the second wakeup pattern, it is possible to get longer bit times without sacrificing false alarm rate. The first wakeup sequence primarily determines bit duration and hence the wakeup receiver sampling rate, and the second wakeup sequence of the hierarchy primarily determines the false alarm rate. For this reason, in neighborhood meshes with potentially longer links and lower SNR, the use of the hierarchical first and second wakeup sequence is more important to minimize the average power of the wakeup receiver to less than 10 uA while retaining the mesh hop latency to &lt;2 ms in the case where the wakeup pattern length is approximately 2 ms in total length of first sequence and second sequence. 
     It was previously noted that for the prior art operating at the 10 uA level, Bluetooth was capable of 5.4 MB/day and WiFi was capable of 18 MB/day. However, using the prior art Bluetooth connection at 1 ms/500 ms would result in a latency of 2 seconds per hop, and Wifi at 1/6000 ms would result in latency of 24 seconds per hop, whereas the latency of the present invention for a first and second wakeup sequence of 1 ms each results in a latency of well less than 3 ms per hop, providing a latency improvement of ˜100× for Bluetooth and ˜1000× for WiFi. 
       FIG.  7    shows a process flow for a wakeup receiver using the hierarchical wakeup sequence. The wakeup receiver  304  of  FIG.  3    may detect RF energy  704  by rectification of incoming RF energy against a threshold for ultra-low power consumption (the rectifier is passive and the threshold detector requires minimal power), by mixing incoming RF to baseband with amplification and detection to detect the envelope of the RF, which is more sensitive while consuming a miniscule amount of current which is only slightly greater than rectification. When RF packet energy is detected by one of these methods in step  704 , a low rate preamble detection process occurs  706  for the duration corresponding to  440  of  FIG.  4   , optionally followed by a high rate preamble detection process  708  (for hierarchical wakeup processing) corresponding to  456  of  FIG.  4   . When the wakeup sequence corresponds to the unicast wakeup sequence of a particular mesh receiver, the corresponding mesh receiver wakes up  710 , enables the mesh station transmitter  302  of  FIG.  3    to acknowledge the wakeup (using a mesh WLAN packet), receives mesh packets from the adjacent station, and sends an acknowledgement, thereafter either returning to sleep  712  and waiting for the next wakeup packet  704 , or sending its own wakeup packet to the next hop station, each station repeating the hop sequence until the destination station or gateway is reached. Steps  710  and  712  are shown in dashed lines for reference, as these functions are performed by the mesh transmitter and receiver, and not the wakeup receiver of  FIG.  7   . Additionally, station RSSI data and other information as described in the tables of  FIGS.  2 A and  2 B  are maintained for stations which have previously transmitted mesh data to the wakeup receiver, which may be periodically accomplished by having each station transmit a broadcast packet so that all adjacent stations may wake up and update their respective station tables as shown in  FIGS.  2 A and  2 B . 
     The mesh station of  FIG.  3    shows the transmit processor  302  as previously described, which is capable of transmitting keyed wakeup sequences by keying the RF transmitter on and off, or by using entire packets which may be used to form wakeup sequences, or alternatively, using packets for particular protocols including 802.11 family of wireless packets, Zigbee packets, or Bluetooth packets. Additionally, the transmit on/off 1/0 sequences may be formed by having the transmit processor send a long baseband packet to be mixed to a carrier frequency and transmitted, with the on/off keying performed by turning on and off any of: the RF amplifier, the mixer, or any other RF chain components which amplify or couple the RF to the antenna, thereby forming the desired 1/0 pattern of the wakeup sequence. The wake receiver process  304  compares an incoming wakeup sequence to a station-specific receiver address and a broadcast address, taking the device out of sleep mode when a match is made. Optionally, the wake-up processor  304  also processes a command such as an instruction to enable the mesh station to operation with a particular protocol or channel. The mesh receiver  308  is able to receive and process the specified protocol type and frequency channel as specified in the optional command part of the wakeup sequence as was described in  FIG.  4   . For certain applications, it may be desirable for the mesh station  300  to determine a location via GPS, or determine a location using a WiFi protocol, or to detect movement using an accelerometer as provided by location and motion functions  314 . An IPv6 subnet router  316  is provided for forming and operating on the subnet of mesh stations, and the route/neighbor table  318  is provided for local subnet routing based on providing SOC metrics so that the stations are equally taxed for power consumption over the life of the local battery. The route tables may also include entries indicating a route cost or available bandwidth so that uniform utilization of the mesh stations may occur by including route utilization information in the route tables so these are considered in the route metric. 
       FIG.  8    shows a process flow for the transmitter in a mesh data transmission mode, which starts with forming the wakeup pattern of 1s and 0s using entire WLAN packets or keyed RF in step  802  corresponding to the wakeup-pattern of a unicast target device. The transmitter may emit a “self-CTS” on the channel using a prior art method to prevent other stations from transmitting during the interval the transmitter is sending the wakeup sequence. After transmission of the self-CTS and wakeup pattern, if an ACK is not received, a retransmission step  802  is performed, or if the ACK is received, transmitting mesh data using the specified protocol  806 , and finally either receiving an ACK and returning to step  802  when the next transmit wakeup even occurs, or retransmitting the previous data  806  if an ACK was not received. 
       FIG.  8    may be understood for periodic advertising by transmitting a broadcast sequence for which all mesh stations are responsive. In the advertising mode, broadcast wake-up sequences are periodically transmitted to surrounding mesh stations (such as with the hierarchical wakeup patterns of waveform  440 ), with the first and second sequence generation and transmission is called in step  802 , which generates the first sequence  440  and optionally second sequence  442  for the hierarchical wakeup pattern. The advertisements are infrequently transmitted  802  for the purpose of allowing each device to update its station table  318  of  FIG.  3   , with the ACK  804  being optional, and no data being transmitted  806  or received  808 . 
       FIG.  9    shows the process for a mesh receiver, which is only powered on receipt of a wake-up frame identifying the present mesh as destination, such as by use of a unique wakeup pattern for that station. The mesh receiver receives the packets, acks them (as shown in series  601  of  FIG.  6 B- 6 E ), and initiates the transmit sequence (wakeup, ack, transmit data, ack, sleep) in step  904 . 
     In another aspect of the invention using hierarchical wakeup sequences, the first sequence or the second sequence uses a pattern which varies over time and is known to all of the devices in a local mesh. One type of security exploit the wake-up receiver is susceptible to is an exploit where a listening hostile device learns the first wakeup sequence and second wakeup sequence and launches a “battery attack” on the mesh devices by repetitively sending wakeup sequences and causing the mesh receivers to draw excess current in the wake-up state for non-existent packets. This may be addressed by providing a series of time-stamped wakeup pattern, such as by using a time-synchronized series of unique wake-up patterns known only to the mesh devices, for example where the public (shared) key is sent to all nodes in a broadcast command from an initial state. In one example of the invention, the first wake-up sequence is a pseudo-random sequence known to the mesh transmitters and mesh wake-up receivers. However, this may not be desirable since the objective of the first wakeup sequence is low power and is typically a short sequence. In another embodiment of the invention, the second wakeup sequence is longer and is used for the time-stamped wakeup pattern, as the receiver is subsequently enabled after the second wakeup sequence is a match for a particular mesh device. 
       FIG.  10 A  shows a perspective view of an example package tracking and delivery system using the present invention. In one example of the invention, a distribution warehouse  1001  as one or more warehouse access point nodes  1027  for communication with mesh nodes inside the warehouse, and with a transit point node  1029  detecting that packages which are outfitted with mesh devices have left the warehouse for distribution to customers. The packages may be delivered by drones ( 1002 ,  1004 ,  1006 ,  1008 ,  1010 , and  1022 , and trucks  1030  and  1032 , each drone or truck having a local mesh node, a GPS or other location tracking system, and an LTE wireless communication system which transmits location and package status to a remote tracking server such as through the LTE wireless network  1007 . The drone wireless stations  1002 ,  1004 ,  1006 ,  1008 ,  1010 ,  1022 , are similarly outfitted with GPS or location tracking system, a mesh node for communication with the package or package mesh nodes they transport, and an LTE wireless system for communication with an LTE network  1007 . A delivered package  1015  may be detected by a residential mesh or access point in residence  1014  for confirming delivery to the resident apart from the notification provided by the delivery drone or truck. Alternatively, the drone wireless stations  1002 ,  1006 ,  1008 ,  1010 ,  1022  and truck wireless stations  1030 , and  1032  each may locally form a separate mesh with each other when in proximity, each station in communication with at least one adjacent station capable of providing updates through the LTE network  1007  or a mesh gateway or access point back to the distribution warehouse  1001  or other point of access, thereby communicating data about package deliveries and delivery status to the various delivery destination customers  1012 ,  1014 ,  1016 ,  1018 ,  1020 ,  1024 ,  1026 , and  1028 . In another alternative embodiment, the packages which are outfitted with mesh nodes transmit location information to each other, which is transmitted back to the warehouse  1001 . As is clear from the number of moving mesh stations of  FIG.  10 A , it may be desirable for at least one mesh station to have an accelerometer, GPS receiver, or WiFi location information  314  for indicating when it is on the move, so that it can rebuild its database of neighbor mesh nodes, as well as periodically provide location updates to the central warehouse  1001  which provides updates to the various package recipients. 
       FIG.  10 B  shows a neighborhood tag tracking example of the mesh network where a local mesh is formed by stations within a particular household, or alternatively, a mesh network is formed by mesh stations in houses  1050 ,  1052 ,  1054 ,  1056 ,  1058 ,  1062 , and  1064 . Pets  1074 , and  1062  in the neighborhood may wander within established boundaries determined by the fixed station locations, such that when an animal moves beyond its established boundary (based on RSSI, GPS, signal strength to one or more locations, or presentation near an unexpected remote mesh station), an alarm may be sent to its owner, accompanied by the current location, or a continuously updated series of locations for providing a movement vector. In one example, a trigger for the sending of a location message occurs when the mesh network examining known stations and Received Signal Strength Indicator (RSSI) associated with the animal&#39;s normal range of movement detects proximity to a previously unknown mesh station after losing contact with a known mesh station. For example, mesh stations  1058  or  1060  may be known for pet  1062  in a backyard adjacent to mesh station  1058 , whereas lost pet  1074  may be associated with backyard  1056 , such that when station  1056  loses communication with pet  1074 , or the receiving gateway receives information that pet  1074  is not in communication with  1056  but is in communication with  1050  and  1052 , an alert indicating the location of the pet may be sent to the owner. 
       FIG.  10 C  shows a “smart city” example, where the mesh nodes of each household  1050 ,  1052 ,  1056 ,  1058   1060 , and  1064  are in local communication with aspects of associated city infrastructure, and city services provided through a mesh network which is part of signposts  1066   1068 , and  1070 , and light pole mesh stations  1075  and  1077 . Other mobile or fixed mesh stations may be placed where needed for communicating with other mesh stations which may momentarily present themselves and exchange information. 
       FIG.  10 D  shows an example home  1064  from  FIG.  10 C , which may include a residential home security or home infrastructure information system. A central access point  1080  may be in communication with mesh stations  1081  for reporting electric utility measurement, garbage can mesh station  1082  for confirming refuse pickup, car  1084  mesh device  1083  for vehicle security, or front door mesh device  1086 , which may detect delivered packages. Additional mesh nodes may be dedicated to security alarm systems, motion detectors, furnace and HVAC control systems, security camera systems, and other devices as may be used to provide more efficient use of energy and increased security. 
       FIG.  10 E  shows an example of a sparse mesh network, where only residence  1095  has a gateway  1093 , but this and the other residences  1095 A,  1095 B, and  1095 C each have meshed network-capable devices, such as refrigerator  1091 A,  1091 B,  1092 C, washer  1092 A,  1092 B,  1092 C, dryer  1094 A,  1094 B,  1094 C, dishwasher  1090 A,  1090 B,  1090 C, and other mesh devices which are enabled with Internet of Things (IoT) capable hardware. An ongoing issue in these “smart” appliances is that setup is required for them to be provisioned to a network, which is the prior art process of “joining” or “associating” to a wireless network, requiring configuring the IoT device, which often requires a computer and knowledge of the access point SSID, network key and network key type. Accordingly, few consumers with such “smart” appliances have the patience or time to connect them to a network, and service codes and the like which may otherwise be readable electronically require a service visit to read the repair code the device is attempting to provide. In the example of  FIG.  10 E , only one residence  1095 A has a wireless gateway  1093 A, and perhaps only refrigerator  1091 A is configured to use the gateway, or perhaps no appliances are configured to use it, but gateway  1093  is mesh-enabled according to the present invention. In the mesh network of  FIG.  10 E , not only may the other appliances  1090 A,  1092 A, and  1094 A connect to the internet using the mesh station of refrigerator  1091 A to reach gateway  1093 A, but the appliances in surrounding residences  1095 B and  1095 C may also join this mesh network to send their data through the mesh to device  1091 A, or to access point router  1093 A, and as long as a chain of two stations in receiving range of each other can be formed for each of the mesh nodes, a network path will be available for every appliance or mesh-ready device through the mesh devices to a gateway such as  1093 A. 
     In the present specification, approximately is understood to mean to +/−12 dB for signal levels and +/−50% for distance or other linear measurement. The examples of the specification are set forth for understanding the invention, the scope of which is limited only by the claims which follow.