Patent Publication Number: US-2003236891-A1

Title: Wireless asynchronous response system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims priority from U.S. provisional patent application Serial No. 60/385,631, filed on Jun. 4, 2002, the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     
       BACKGROUND OF INVENTION  
       [0002] The present invention is directed to a wireless response system in order to retrieve responses from a group of individuals at a central location. The present invention is useful in classroom settings, in corporate meetings and in other gatherings of individuals. The present invention may be used with as few as tens of users or as many as thousands of users.  
       [0003] It is known to utilize a bidirectional wireless communication between a base unit and a plurality of response units in order to receive at the base unit the response of users, each of which is provided with a response unit. One such system is disclosed in commonly assigned U.S. Pat. Re. 35,449. The system disclosed in Re. &#39;449 is a two-way system. The base unit sends a synchronizing signal to the response units. Each response unit responds in a unique timeframe in response to the synchronizing signals. The central unit acknowledges receipt of a valid response from each of the transmitting response units. Each response unit, upon receipt of an acknowledgement signal, discontinues transmission of the response. It may be desirable to have a wireless response system in which the need for a transmission from the base unit to the response units is no longer required. In such a system, each response unit transmits a signal upon entry of a selection by the user.  
       SUMMARY OF INVENTION  
       [0004] The present invention is directed to a wireless response system that is capable of enhancing reliability in one-way wireless transmission between response units and one or more base units, notwithstanding the use of even thousands of response units at a single location.  
       [0005] According to one aspect of the invention, a wireless response system and method includes providing at least one base unit having a wireless receiver for receiving wireless signals from a plurality of response units. The response units have a wireless transmitter for transmitting a wireless signal to the at least one base unit. The wireless signal includes digital data. The response unit asynchronously transmits the wireless signals.  
       [0006] The communication may be over a plurality of wireless communication channels that are generally different from each other. The digital data may include an indication on which of the channels the response unit is transmitting. The at least one base unit may decode the wireless signals received by the wireless receiver and determine whether the channel indication of the wireless signal matches the communication channel on which the wireless signal is received. The at least one base unit may accept wireless signals for which the channel indication of the receiver signal matches the communication channel that the wireless signal is received on and may not accept wireless signals for which the channel indication of the received signal does not match the communication channel that the wireless signal is received on. The digital data may further include an address for the response unit. The digital data may further include a sync byte. The digital data may further include an error detection code. The wireless signal may be either a radio frequency signal or an infrared signal. The response units may further include an input selection device. The digital data may include a selection made with the input selection device. The input selection device may be a keypad.  
       [0007] According to another aspect of the invention, a wireless response system and method includes providing at least one base unit having a wireless receiver and a plurality of response units. The response units have a wireless transmitter for transmitting a wireless signal to the at least one base unit. The response units asynchronously transmit the wireless signal. The wireless signal may include digital data. The digital data may include an address for the response unit. The wireless transmitter repeatedly transmits the wireless signal spaced apart by a particular interval that is different for the various response units.  
       [0008] The interval may be a function of a number assigned to the transmitting response unit, such as the address for the transmitting response units. The response units may repeatedly transmit the wireless signal in response to a selection made with an input selection device. The digital data may include a selection made with the input selection device. The input selection device may be a keypad.  
       [0009] The interval may be determined by the formula I=A(B−number)+C(number) where I is the interval and A, B and C are constants and “number” is the number assigned to the transmitting response unit. The wireless transmitter may repeatedly transmit the wireless signal for a particular number of transmits. The particular number of transmits may be selectable. The response unit may include an input selection device and the particular number of transmits may be selectable with the input selection device.  
       [0010] The input selection device may be a keypad. The digital data may further include a sync byte. The digital data may further include an error correction code. The wireless signal may be either a radio frequency signal or an infrared signal.  
       [0011] According to another aspect of the invention, a wireless response system and method for retrieving user responses in a user-occupied area which accommodates a multiplicity of users includes providing a plurality of base units that are dispersed the user-occupied area. The base units have a wireless receiver for receiving wireless signals. A multiplicity of response units are provided having an address that distinguishes individual ones of the response units. The response units have an input selection device for receiving the user selection and a wireless transmitter for asynchronistically transmitting a wireless signal to the base units. The wireless signals include digital data. The digital data includes an address to the response unit and a selection made with the input selection device. A computer system is provided that includes a communication system for retrieving user selection from base units. User selections may be retrieved from the response units by base units that are capable of receiving response signals and the user selections are identified by the address irrespective of which base unit receives a particular wireless signal.  
       [0012] The wireless communications system may be a hub-and-spoke network that may be hardwired, such as an Ethernet system, or a wireless network. The wireless transmitter may repeatedly transmit the wireless signals based in part by particular intervals that are different from the other response units. The particular intervals may be a function of the address of the transmitting response unit. At least some of the base units may be capable of receiving wireless signals at different communication channels. The digital data for at least some of the response units may include a channel indication which indicates on which of the channels that response unit is transmitting.  
       [0013] These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0014]FIG. 1 a  is a block diagram of a wireless response system, according to the invention;  
     [0015]FIG. 1 b  is the same view of the response system in FIG. 1 a  configured in a different manner;  
     [0016]FIG. 1 c  is the same view of the response system in FIG. 1 a  configured in a different manner;  
     [0017]FIG. 2 is a flowchart of a program carried out by a response unit; and  
     [0018]FIG. 3 is a flowchart of a program carried out by a base unit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0019] Referring now specifically to the drawings, and the illustrative embodiments depicted therein, a wireless response system  10  includes one or more base units  12  and a plurality of remote response units, or response units,  14  (FIG. 1 a ). Response units  14  transmit a wireless signal S to one or more base units  12 . Wireless signal S may be a radio frequency signal transmitted between a receiver (not shown) in the response unit  14  and a receiver  16  in base unit  12 . The advantage of radio frequency signals is that they may have improved directional capabilities. If a radio frequency signal is used, it may be encoded with data bits using leading edge-to-leading edge timing or trailing edge-to-trailing edge timing as disclosed in commonly assigned U.S. Pat. No. 5,724,357, the disclosure of which is hereby incorporated herein by reference. However, other encoding techniques may be utilized. Wireless signal S may alternatively be an infrared signal, which is transmitted with a light-emitting diode in response unit  14  and a light sensor in response unit  12 . Known encoding techniques may be utilized with an infrared system.  
     [0020] Especially when a large number of response units  14  are utilized, such as hundreds or thousands of units, it may be desirable to have multiple base units  12   a ,  12   b ,  12   c  . . .  12   n  each receiving signals in a communication band that is distinguishable from the communication bands of the other base units as illustrated in FIG. 1 b . Alternatively, multiple receivers  16  may be included in an individual base unit. Base unit(s)  12  may include a microcomputer  18  and a storage device, such as an EEPROM  20 . An input  22  may be used to modify settings, which are stored in EEPROM  20 . For example, input  22  may be used to select a communication channel, or band, that the particular receiver  16  is receiving on. The communication channel for the particular receiver  16  would be stored along with other settings in EEPROM  20 . As would be understood by those skilled in the art, each communication channel would be a distinct set of frequencies that are distinguishable from the frequencies of other channels  16 . Base unit(s)  12  includes a serial port  24 , which supplies serial data to a personal computer  26 . Computer  26  compiles data received from serial port  24 , which is received from response units  14  by base unit(s)  12 .  
     [0021] Response units  14  include a transmitter  28  and a microcomputer  30 . Transmitter  28  transmits wireless signal S. Microcomputer  30  controls transmitter  28 . Each response unit  14  may include an input device, such as a keypad  32 , in order to receive input selections. Microcomputer  30  receives inputs from keypad  32  and causes transmitter  28  to transmit signal S. Response units  14  may further include a storage media, such as an EEPROM  31 , for storing settings in a non-volatile manner. Response units  14  further include a battery  33  to provide a portable power source.  
     [0022] An example where the use of multiple communication channels are useful is in a seminar having multiple breakout groups each of which may be supplied with an individual base unit set at a channel different from the other base units. Such a system can be set up in separate rooms or in separate groups within a room. Another example may be if two unrelated organizations are sharing a common convention facility where it may be desirable to have one or more base units for one organization operating on one or more communication channels that are different from the communication channel(s) for the other organization. This inhibits cross talk between organizations. Other examples may suggest themselves to the skilled artisan.  
     [0023] The present invention may be embodied in a response system  10  that is usable with a very large group such as thousands and even tens of thousands of users as illustrated in FIG. 1 c . System  10  may be used in a large facility  104 , such as a convention center, arena, stadium or the like. The system may include a large number of base units  12  which are in communication with a computer system  26  by way of communication systems generally illustrated as  24   a  and  24   b . The communication system may include a network hub  24   b  which communicates with a plurality of base units  12  through a router  24   a . Communication system  24   a ,  24   b  may be a hardwired network, such as an Ethernet network, a wireless network, or the like. If a wireless network, the frequency of the wireless network would be different than the frequency of the wireless signals received by base units  12 . For convenience, a hub  24   b  and a series of base units  12  connected with that hub may be thought of as a grouping  102  with the groupings spread throughout the arena  104 . Many, if not all, of base units  12  may be operational on a common channel. A multiplicity of response units (not shown in FIG. 1 c ) each include unique addresses. Wherever a particular response unit is within arena  104 , it would supply a wireless signal in response to actuation of a key in keypad  32  that would be received by one or more base units  12 , but not all base units  12 . Therefore, some of the wireless signals of some of the response units will be received by some of the base units, but other base units will receive wireless signals from other response units. Because each base unit  12  does not receive signals from all of the keypads, the collision between wireless signals may be reduced due to the geographic layout of wireless response system  10  in arena  104 . However, because each base unit has a unique address, the base unit  12  receiving the wireless signal from that response unit would decode the signal and send the response data to computer system  26  via communication network  24   a ′,  24   b′.    
     [0024] By way of example, if 100 base units  12  were each capable of receiving wireless signals from approximately 50 response units, the system in FIG. 1 c  could accommodate 5,000 response units. The ability to supply 5,000 unique addresses merely requires a longer address. This is merely for illustration only. Systems with fewer than or greater than these numbers could be accommodated. However, the ability to mitigate collisions is due in part to the geographic separation of the base units and the fact that they will only interact on near field basis with response units in their geographic vicinity.  
     [0025] In the illustrated of embodiment, hubs  24   b ′ may be 32 port hubs and may be on a wireless Ethernet network operating at the 802.11 standard, which is at a frequency of between 2.4 gigahertz and 5 gigahertz. Wireless transmitter  28  may operate in the illustrated embodiment between 300 and 345 megahertz and 900 megahertz. As can be seen, there would be no conflict between the different wireless systems.  
     [0026] Wireless response system  10  includes a response unit program  34  (FIG. 2). Response unit program  34  may be carried out by microcomputer  30 . Program  34  is initiated when a user makes a selection, such as by pressing, at  36 , one of the keys of keypad  32 . The system then identifies at  38  the key that was pressed. If it is determined at  38  that the key that was pressed was not a valid key, the keypad is shutdown at  40 . An invalid key may be one that is set to be not usable for a particular exercise, or the like.  
     [0027] If it is determined at  38  that a valid key has been entered, it is determined at  42  whether the key entered was the key, or keys, requesting entry of the options mode. If so, the user is provided with menus at  44  for changing the options and for saving the new settings to EEPROM  31 . If it is determined at  42  that the identified key, or keys, is not for entering the options mode, the key is placed in a buffer at  46 . Microcomputer  30  then assembles a message at  48 . The message may be comprised of digital data that includes a sync byte at  50  in order to indicate the beginning of a transmission and a preamble at  52  in order to provide time for the receiver  16  to settle. The digital data may further include an address  54  that is assigned to that response unit. The message may further include a channel identifier  56  for the channel to which the particular response unit is set up for, and key press information  57  indicates which selection was made by the user with keypad  32 . The message then concludes with an error detection code  58  in order to provide parity. Examples of error detection codes include CHECKSUM, CRC, and the like.  
     [0028] After the message is assembled at  48 , the digital data is transmitted at  60  by transmitter  28 . A generally random offset is determined at  62 . The random offset may be calculated from a number assigned to the particular responding unit, such as, for example, the keypad address for the response unit. The offset, or interval, is calculated using the equation A×(B number)+C×(number). A, B and C are constants and “number” is the number assigned to the transmitting response unit. This equation provides adequate intervals between transmissions without unduly extending the interval. In the illustrative embodiment, A is 15, B is 50 and C is 2. However, other constants and other equations may be used. The purpose of the random offset calculation is in order to determine a time interval after which the transmission will be repeated. By having the random offset based upon a number assigned to the transmitting unit, such as the keypad address for the particular response unit, the offset will be different for each response unit. Therefore, even if transmissions collide between two response units, the next transmission by those units should be non-colliding because of the difference in the offset time intervals. It should be understood that other techniques might be used to calculate a different offset for most or all of the response units. However, the calculating of offset as a function of the address for that unit provides a convenient technique for assigning intervals to each response unit. This is because each unit already has an address that is different from other response units.  
     [0029] After the random offset is calculated at  62 , it is determined at  64  whether a number of transmits have been completed. If not, the program returns to  60  for another transmission of the assembled message. The number of repeat transmits may be established within EEPROM  31 . The number of complete transmits may be stored in the EEPROM  31  as part of the setup mode  44 . This would allow a user to change the number of repeat transmissions as a function of the environment in which the unit is set up. For example, if system  10  is being used in an environment with a large number of response units, it may be desirable to repeat the number of transmissions in order to avoid conflicts. Also, in environments that are susceptible to electromagnetic interference (EMI), it may be desirable to set a larger number of retransmissions. Other examples will suggest themselves to those skilled in the art.  
     [0030] After the number of transmissions is complete at  64 , the condition of battery  33  is examined at  66 . If it is determined that the battery is low on charge, an indicator is set at  68 . The indicator may be a flashing of display segments or other known indications, such as illumination of an LED, or the like. The keypad is then shutdown at  40  awaiting a further key press at  36 .  
     [0031] Base unit(s)  12  performs a base control program  70  (FIG. 3). Program  70  begins when the particular base unit(s) is powered up at  72 . It is determined at  74  whether the channel change button  22  has been pressed. If so, the channel is then changed at  76  and the new channel setting is saved in EEPROM  20  at  78 . The change in channel at  76  changes the frequency band with which the particular receiver  16  is tuned for receiving a signal S. By changing the channel at  76 , the frequency band for that signal is changed.  
     [0032] If it is determined at  74  that the channel change has not been pressed, the channel is read at  80  from EEPROM  20  and a channel frequency is set for that receiver  16 . Serial communications over serial line  24  are initialized at  82  and receiver section  16  is set to receive at  84  assembled messages  48  sent via RF signal S.  
     [0033] It is then determined at  86  whether a valid RF signal has been received. This is determined by evaluating the number of bytes received, verifying that the CHECKSUM is correct and that the channel ID is identical with the channel selected for that base unit(s) as stored in EEPROM  20 . If valid RF data is received, the decoded data is placed in a serial communication buffer at  88 . If valid RF data is not received at  86 , the receiver section continues to look for assembled messages at  84  and  86 .  
     [0034] After data is placed in serial communication buffer  88 , it is determined at  90  whether the serial line is available for sending the serial data to personal computer If so, a serial data stream is sent at  92 . If it is determined at  90  that serial data should not be sent, the program returns to  84  where the receiver looks for assembled messages over its communication channel.  
     [0035] Thus, it can be seen that wireless response system  10  is especially useful in reliably retrieving information, at one or more base units, from a plurality of users that is sent asynchronously. By including a channel identifier with the assembled message, a message may be ignored if it is not destined for a particular base unit(s). This reduces the tendency for proximity to a base unit(s) to overwhelm the receiver of that base unit(s). By providing for an offset delay in retransmission of the signal, that is different for each response unit, the ability to overcome transmission collisions is greatly enhanced. Moreover, the ability to selectively set the number of transmission retries allows for adapting the system to the environment while minimizing unnecessary retries and increasing the reliability of the system.  
     [0036] It should be understood that the various features of wireless response system  10  may be used alone or in combination.  
     [0037] Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.