JPH1155178A - System and software method for radio data base station operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save time without bringing the lowering of a real signal, to reduce cost and to eliminate a 'false busy' signal by deciding whether or not a received signal strength index (RSSI) of a start part of a packet is larger than prescribed threshold and setting a busy bit to send a busy signal when it is larger than the prescribed threshold. SOLUTION: After a radio data base station (RDBS) 12 receives a start part of an uplink packet, the RDBS 12 measures an RSSI of the start part of the uplink packet and compares the measurement value with a prescribed threshold. When the RSSI of the start part of the uplink packet exceeds the prescribed threshold, the RDBS 12 continues to send a busy signal. When the RSSI of the start part of the uplink packet does not exceed the prescribed threshold, the RDBS 12 releases a busy signal and seeks a start point of another uplink packet. This operation eliminates the necessity for a hardware attenuator and maintains the quality of a received signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a radio base station system and control of a radio data base station, for example, the "sensitivity" of a radio data base station without the need for a hardware attenuator and without reducing the actual signal. And a software method for lowering it.

[0002]

2. Description of the Related Art In a radio data system, a radio data base station (RDBS) is used.
o data base station) Sometimes the receiver is much more sensitive than the wireless receiver, in this case
It is desirable to attenuate the receiver signal in the RDBS to balance the uplink and downlink channels. The uplink channel is the communication from the wireless terminal to the RDBS, and the downlink channel is
Communication from RDBS to wireless terminal. This is especially important when the frequency reuse pattern is dense. In this case, the RDBS does not want to receive a signal addressed to another RDBS on the same frequency.

When the RDBS detects the beginning of a packet (uplink packet) in the uplink channel, it sets a busy signal on the downlink channel (ie, sets a busy bit and transmits a busy signal to another RDBS). ) To indicate that the uplink channel is busy. The busy signal operates during an uplink packet. During this busy condition, other wireless terminals registered on the cell begin using the uplink channel until the wireless terminal currently using the uplink channel has completed transmitting the uplink packet. Is not allowed. When the uplink packet is completely received, the RDBS controller releases the busy signal.

[0004] With such a method used in the DataTAC infrastructure marketed by Motorola, the RDBS controller may incorrectly detect the beginning of an uplink packet due to co-channel interference. For example, RDBBS A and RDBSB send and receive uplink packets on the same frequency. The wireless terminal sends an uplink packet to RDBSA. RDBSB A receives a strong signal and RDBSB receives a weak signal. RDBS A
Both RDBS B transmit a busy signal individually to other wireless terminals.

As described above, the RDBS controller uses its RDBS
Inform the BS that the uplink channel is busy, even if the uplink packet is not addressed. When multiple RDBS receive an uplink packet,
RDBSs decode the uplink packets and
Forwards uplink packets to the RDBS controller for processing. This means that multiple cells "busy out" the uplink channel even if the wireless terminal does not operate on that cell (i.e., a "false busy" situation). produce)
Means that. RDBS is an uplink to the target RDBS
Continue sending a "false busy" signal until the entire packet is received. Creating a "false busy" situation limits uplink processing power, placing unnecessary processing burden on the RDBS controller (rejecting duplicate messages).

[0006] A plurality of RDBSs (for example, RDBS B) are
The method currently used in the state of the art to prevent picking up signals destined for (eg, RDBS A) is to manually tune the hardware receive attenuator in the RDBS and to remotely tune the remote receiver, such as other cells using the same frequency. The purpose is to not have sensitivity enough to receive a signal from the wireless terminal. This is a time consuming manual operation that requires a site survey and requires additional hardware components in the RDBS.

As a result of time consuming manual work and extra hardware attenuators used to prevent RDBS receivers from being much more sensitive than wireless terminal receivers, multiple RDBSs may have the same uplink A "false-busy" signal that does not require a hardware attenuator, as a result of a longer "false-busy" signal when receiving a packet, and saves time, lowers costs, and does not cause degradation of the real signal There is a need for a system and method for reducing emissions.

While the preferred embodiment of the present invention will be described with reference to the drawings, this is by way of example only.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The software attenuation method described herein eliminates the need for a hardware attenuation device and maintains the quality of the received signal. The software damping method is easily controlled, either automatically or remotely.

[0010] Wireless data systems have either a single frequency reuse pattern or a multiple frequency reuse pattern. Radio frequency (RF) designs for wireless data systems are similar in nature to cellular voice. Since the RF spectrum is limited, it is necessary to reuse frequencies. The amount of frequency reuse depends on available spectrum, required system capacity and RF constraints (terrestrial; maximum allowed carrier-to-interference ratio; equipment power). Wireless data systems typically require at least 12 frequency reuse patterns. This frequency reuse pattern is based on the PM100 personal computer commercially available from Motorola.
International Association of Memory Cards (PCMCIA: Personal Computer)
Memory Card International Association) Slot Wireless Data Link Access Protocol (RD-LAP: radi
o data link access protocol) Required to provide in-building coverage for low power devices, such as RF modems. This design requires a nearby radio data base station (RDBS) deployment with low uplink channel power.

[0011] More than one RDBS on the same frequency can receive an uplink packet from a wireless terminal that is registered with only one of those RDBSs.
This is because wireless terminals are used in high-rise buildings,
This can occur when operating near the edge of the cell. Remote RDBS
It is desirable not to detect the presence of a signal transmitted by the wireless terminal and not addressed to the RDBS. This is to prevent "false busy" which wastes valuable airborne communication media time.

FIG. 1 illustrates an RDBS according to a preferred embodiment of the present invention.
FIG. RDBSs are deployed at wireless sites to provide the required wireless coverage. This integrated RDBS1
2 comprises at least one RF transceiver 28 and an RDBS controller 30. The transceiver has at least one signal output 29. The RDBS controller 30 includes a busy signal generator 32 and at least one
A station identifier comparator 34 having two predetermined station identifiers 36,
It comprises a signal detector 38, a signal strength memory unit 40 and a predetermined threshold 42. Busy signal generator 32 is coupled to RF transceiver 28. Station identifier comparator 34 and signal detector 38 are each coupled to busy signal generator 32 and each to RF transceiver 28. The signal strength memory unit 40 has a first input 41 coupled to a predetermined threshold, a second input 43 coupled to an RF transceiver, and an output 45 coupled to a busy signal generator. The RDBS controller is preferably implemented in a microprocessor, digital signal processor, microcontroller or a combination thereof, and includes various elements 32,34,36,38,40,
41 is preferably implemented in software,
Those skilled in the art will appreciate that they may be implemented as hardware circuits or a combination of hardware and software. All such embodiments are encompassed by the software methods and systems of the present invention.

An RF transceiver 28 sends data on radio frequency between the RDBS controller 30 and a wireless terminal. The RDBS controller 30 constructs the RD-LAP RF protocol. (The RD-LAP protocol is used to send data over narrowband radio frequencies.) Wireless terminals allow subscribers to send and receive data over infrastructure (eg, DataTAC infrastructure available from Motorola). It is a device used for. The wireless terminal is used for infrastructure radio coverage and
The entire area can be moved. The wireless terminals supported by each infrastructure are composed of two separate components: a wireless packet modem and a data terminal device. Wireless packet modems send and receive data packets on wireless channels. The data terminal device provides a wireless channel user interface function.

Digital sense multiple access (DSMA: di
gital sense multiple access) The RDBS 12 in the wireless data system uses the uplink from the wireless terminal.
Detects packet presence and sets busy signal (ie sets busy bit and sends busy signal to other RDBS)
To prevent other wireless terminals from transmitting on a particular uplink channel at the same time. Such DSMA wireless systems are available from various manufacturers, such as Motorola.
It is sold under various trademarks such as DataTAC. To do this, the RDBS controller 30 detects the beginning of the uplink packet, such as a code synchronization signal (eg, a regular repetitive pattern), and consequently the uplink packet.
It is common to set a channel busy.

FIG. 2 is a cell diagram for explaining a preferred embodiment of the present invention. In FIG. 2, first RDBS 12 and second RDBS 14 both transmit and receive signals on a common frequency (for example, frequency 1). Wireless terminal 10
Sends a packet (uplink packet) having at least one station identifier signal identifying the uplink packet to be addressed to the first RDBS 12 in the uplink channel. However, this uplink
The packet is received and decrypted on both the first RDBS 12 and the second RDBS 14. As a result, the first RDBS 12 and the second RDBS
14 sends a busy signal in the downlink channel to indicate that the uplink channel is busy. Both the first RDBS 12 and the second RDBS 14 keep the cell in use, preventing other wireless terminals from using the cell. After the first RDBS 12 and the second RDBS 14 respectively set the busy signal in the downlink channel,
The BS 12 and the second RDBS 14 receive and decode the station identifier signal. Since the station identifier signal matches the predetermined station identifier stored in the first RDBS 12 and does not match the predetermined station identifier stored in the second RDBS 14, the first RDBS 12 continuously transmits a busy signal in the downlink channel. And completely receive the uplink packet and release the busy signal at the next opportunity. However, the second RDBS 14 is
4 decrypts the station identifier signal and releases the busy signal in the downlink channel as soon as it identifies that the station identifier signal does not match the predetermined station identifier. Thus, the station identifier signal is transmitted to the remote RDBS (eg, the second RDBS).
Is notified to cancel the busy signal. As a result, the RDBS is connected to the wireless terminal 10 registered in the cell.
, A busy signal (ie, "intelligent busy") can be set in the downlink channel. The RDBS 12 may also discard all messages sent from the wireless terminal 10 that are not registered in the cell (ie, “messag
e discard))).

FIG. 3 is a diagram of an uplink packet according to a preferred embodiment of the present invention (eg, a 19.2 baud uplink packet in a DataTAC wireless data system). RDBS controller 30 receives the beginning of an uplink packet (eg, code synchronization signal 52) from wireless terminal 10. The RDBS controller 30 decodes the start of the uplink packet,
Set up the uplink channel busy by sending a busy signal in the downlink channel. RD
The BS 12 transmits a busy signal to another wireless terminal. When the frame synchronization signal 54 of the uplink packet is received within a predetermined time interval (for example, about 50 ms), the RDBS 12 continuously transmits a busy signal to another wireless terminal. If the RDBS controller does not receive the frame synchronization signal 54 within a predetermined time interval, the RDBS controller
Releases the busy signal and looks for the beginning of another uplink packet.

FIG. 4 is a flow chart of the busy control mechanism according to the preferred embodiment of the present invention beginning at step 62. Stage 64
At, the RDBS 12 detects the beginning of the uplink packet. In step 65, the RDBS 12 determines the received signal strength indicator (RSSI) based on the signal strength at the beginning of the uplink packet.
ator). In step 66, the RDBS 12 determines that the RSSI at the beginning of the uplink packet is a predetermined threshold 42
Is determined. If the RSSI at the beginning of the uplink packet is smaller than a predetermined threshold 42, RD
BS 12 looks for the beginning of another uplink packet in step 64. If the RSSI at the beginning of the uplink packet exceeds the predetermined threshold 42, the RDBS 12 sets a busy signal in the downlink channel at step 68 to indicate that the uplink channel is busy. . The RDBS 12 completely receives the uplink packet in step 69 and releases the busy signal in step 70. Uplink recently received by RDBS
The busy control mechanism for the packet ends at step 71,
The RDBS starts looking for the beginning of another uplink packet.

FIG. 5 is a flowchart of a busy control mechanism according to a first alternative embodiment of the present invention beginning at step 72. Stage 7
At 4, the RDBS 12 detects the beginning of the uplink packet with signal strength. In step 76, upon detecting the beginning of the uplink packet, the RDBS 12 sets a busy signal in the downlink channel indicating that the uplink channel is busy. In step 77, the RDBS 12 measures the received signal strength indicator (RSSI) based on the signal strength at the beginning of the uplink packet. In step 78, RDBS
12 determines whether the RSSI at the beginning of the uplink packet exceeds a predetermined threshold 42. Uplink ・
If the RSSI at the beginning of the packet is less than the predetermined threshold 42, the RDBS 12 looks for the beginning of another uplink packet (eg, a code synchronization signal) at step 80. If the RSSI at the beginning of the uplink packet is greater than the predetermined threshold 42, the RDBS 12 continues to transmit a busy signal until the uplink packet is completely received at step 81, and releases the busy signal at step 82. I do. RD
The busy control mechanism for the uplink packet recently received by the BS ends at step 83. The ARDBS begins searching for the beginning of another uplink packet. FIG.
9 is a flowchart of a busy control mechanism according to a second alternative embodiment of the present invention. The RDBS starts the busy control mechanism at step 84. The RDBS 12 transmits the uplink
Detect the start of a packet. Based on the detection of the beginning of the uplink packet in step 86, RDBS1
2 sets a busy signal on the downlink channel at step 88 to indicate that the uplink channel is busy. RDBS 12 decrypts the received station identifier signal from the uplink packet at step 90. The RDBS 12 compares the received station identifier signal 56 with a predetermined station identifier 36 of the RDBS 12 at step 92. The received station identifier signal 56 is a predetermined station identifier 3 of the RDBS.
If not, the RDBS 12 releases the busy signal at step 94 to look for the beginning of another uplink packet. In step 92, the receiving station identifier signal 56
If RDBS matches a predetermined station identifier 36 of RDBS 12, RD
BS 12 completely receives the uplink packet in step 96 and releases the busy signal in step 98. RDBS1
2 terminates the busy control mechanism for the recently received uplink packet by the RDBS in step 100,
Start looking for the beginning of another uplink N packet.

FIG. 7 is a flowchart of a busy control mechanism according to a third alternative embodiment of the present invention. The RDBS starts the busy control mechanism in step 104. RDBS controller 30
Detects the beginning of the uplink packet in step 106. The RDBS controller 30 proceeds to step 108
A busy signal is set at step, and at step 109 the RSSI of the beginning of the uplink packet is measured. RDBS
The controller determines at step 110 whether the beginning of the uplink packet (eg, code synchronization signal 52) has a signal strength greater than a predetermined threshold 42. The beginning of the uplink packet 52 is
If it has a signal strength less than or equal to the predetermined threshold 42, the RDBS 12 releases the busy signal at step 112 and seeks the beginning of another uplink packet. If the beginning of the uplink packet 52 has a signal strength greater than the predetermined threshold 42, the RDBS 12
Determines in step 114 whether the frame synchronization signal 54 was detected before a predetermined time. This predetermined time is determined by the protocol.

If the frame synchronization signal 54 is not detected before the predetermined time, the RDBS controller 30 proceeds to step 112.
Release the busy signal and search for the beginning of another uplink packet. If the frame synchronization signal 54 is detected within a predetermined time, the RDBS controller 30 determines in step 116 whether the station identifier signal 56 of the uplink packet identifies an RDBS.

If the station identifier signal 56 in the uplink packet does not identify the RDBS 12,
At 12 the busy signal is released and another uplink packet start point is searched. If the station identifier signal 56 identifies the RDBS 12, the packet header
, The RDBS 12 determines at step 118 whether the packet header 58 is correctly received.

In step 118, packet header 5
If 8 is not received correctly, in step 120,
The RDBS12 determines that the RSSI of the uplink signal is "exit threshold (exit
threshold) ", or wait until the maximum uplink packet length (e.g., time) is reached. When one of these happens,
The RDBS 12 releases the busy signal at step 112 to search for the beginning of another uplink packet. If the packet header 58 is received correctly in step 118, RD
BS 12 completely receives the uplink packet in step 122 and releases the busy signal in step 123. RD
The busy control mechanism for the uplink packet recently received by the BS ends at step 124, and the RDBS begins searching for the beginning of another uplink packet.

The problem with the current state of the art employing a balanced hardware attenuation method is that the signal is (by a manually tuned receive attenuator) that the RDBS controller detects the relevant pattern (eg, the code synchronization signal). It is so low that it cannot be done. The software decay method, only illustrated herein, comprises a predetermined threshold 42, and the beginning of an uplink packet (eg, a code synchronization signal or other suitable pattern) is determined by the RDBS 30 by the RDBS 30.
The threshold must be exceeded before declaring the channel busy. This predetermined threshold 42 can be easily tuned remotely (eg, as a simple network management protocol variable) or automatically, using any method not disclosed herein.

In addition, there is a "window of vulnerability" between the time at which the first wireless terminal 10 transmits and the time at which the RDBS 12 transmits to the other wireless terminals that the channel is busy. Exists. After the first wireless terminal 10 transmits an uplink packet to the RDBS 12, before transmitting to other wireless terminals that the uplink channel is busy,
The second wireless terminal may start transmitting to RDBS12. When this occurs, a collision occurs between the transmissions from the first wireless terminal 10 and the second wireless terminal, which during a “weak window”, causes the second wireless terminal to:
This is because a busy signal indicating that the uplink channel is busy has not been received from the RDBS 12 yet. Thus, the greater the “fragile window”, the greater the probability of a collision.

The software decay method, only illustrated above, shortens the "fragile window". The software attenuation method quickly detects that the uplink channel is busy and communicates this to the RDBS without delay (eg, the RDBS receives the beginning of a packet and immediately sends a busy signal). After RDBS 12 receives the beginning of the uplink packet (eg, code synchronization signal 52), RDBS 12 measures the RSSI of the beginning of the uplink packet and compares this measurement to a predetermined threshold 42. If the RSSI at the beginning of the uplink packet exceeds a predetermined threshold 42, the RDBS 12 continues to transmit a busy signal. Of the beginning of the uplink packet
If the RSSI does not exceed the predetermined threshold 42, the RDBS 12 releases the busy signal and seeks the start of another uplink packet. This software attenuation method is also applied when the RDBS 12 sets the busy signal after determining whether the RSSI at the start of the uplink packet exceeds a predetermined threshold 42.

Although the present invention has been described with respect to particular embodiments, many modifications, changes, and variations will occur to those skilled in the art in light of the above description. Therefore, it is to be understood that the invention is not limited to the above description, but encompasses all such alterations, modifications and variations which are in accordance with the spirit and scope of the appended claims.

[Brief description of the drawings]

FIG. 1 is a diagram of an RDBS according to a preferred embodiment of the present invention.

FIG. 2 is a cell diagram for the purpose of describing a preferred embodiment of the present invention.

FIG. 3 is a diagram of an uplink packet according to a preferred embodiment of the present invention;

FIG. 4 is a flowchart of a busy control mechanism according to a preferred embodiment of the present invention.

FIG. 5 is a flowchart of a busy control mechanism according to a first alternative embodiment of the present invention.

FIG. 6 is a flowchart of a busy control mechanism according to a second alternative embodiment of the present invention.

FIG. 7 is a flowchart of a busy control mechanism according to a third alternative embodiment of the present invention.

[Explanation of symbols]

 28 transceiver 29,45 output 30 RDBS controller 32 busy signal generator 34 station identifier comparator 36 predetermined station identifier 40 signal strength memory unit 41,43 input 42 predetermined threshold

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Carl V. Ashworth 11887 Bayworth Way, San Diego, California, USA

Claims (7)

[Claims] 1. A software method for operating a wireless data base station having a busy control mechanism, comprising: detecting a start portion of a packet having a signal strength; receiving based on a signal strength of the start portion of the packet. Setting a signal strength indicator (RSSI); determining whether the RSSI at the beginning of the packet is greater than a predetermined threshold;
Searching for the start of another packet if the RSSI of the beginning of the packet is less than the predetermined threshold; and setting a busy bit if the RSSI of the beginning of the packet is greater than the predetermined threshold. Setting and transmitting a busy signal. 2. A software method for operating a wireless data base station having a busy control mechanism, comprising: detecting a start of a packet having signal strength; setting a busy bit upon detecting the start of the packet. Transmitting a busy signal; setting a received signal strength indicator (RSSI) based on the signal strength at the beginning of the packet; and determining whether the RSSI at the beginning of the packet is greater than a predetermined threshold. If the RSSI at the beginning of the packet is less than the predetermined threshold, releasing the busy signal to search for the start of another packet; and the RSSI at the beginning of the packet.
Transmitting a busy signal if is greater than the predetermined threshold. 3. A software method for operating a wireless data base station having a busy control mechanism, comprising: detecting a start of a packet; and detecting a busy bit based on the detecting of the start of the packet. Setting; based on the setting the busy bit,
Transmitting a busy signal; decoding a station identifier signal from the packet; comparing the station identifier signal with a predetermined station identifier for the wireless data base station;
Releasing the busy signal if the station identifier signal does not match the predetermined station identifier of the wireless data base station; and the station identifier signal matches the predetermined station identifier of the wireless data base station. Transmitting said busy signal in any case. 4. The method of claim 3, wherein said step of continuously transmitting a busy signal further comprises: completely receiving said packet; and releasing said busy signal. 5. A software method for operating a wireless data base station having a busy control mechanism, comprising: detecting a start of a packet; setting a busy bit; transmitting a busy signal; Received Signal Strength Indicator (RSSI) where the start of the message is greater than a predetermined threshold
Determining if the RSSI of the beginning of the packet is greater than the predetermined threshold, and whether a frame synchronization signal of the packet is detected before the frame synchronization signal expires. Determining whether or not;
Releasing the busy signal if the frame synchronization signal is not detected before the frame synchronization signal expires; if the frame synchronization signal is detected before the frame synchronization signal expires, Determining whether the station identifier signal of the packet is equal to a predetermined station identifier at the wireless data base station; if the station identifier signal is equal to the predetermined station identifier at the wireless data base station, Determining whether to receive correctly; releasing the busy signal after a timeout or when the RSSI of the packet falls below a threshold if the packet header is not correctly received; and If the packet header is received correctly, the packet is completely received, and then the busy signal Releasing the method. 6. A transceiver; a busy signal generator coupled to said transceiver; a station identifier comparator having a predetermined station identifier coupled to said busy signal generator and coupled to said transceiver; and said busy signal generator. A signal detector coupled to the transceiver and to the transceiver. 7. A transceiver; a signal output of the transceiver; a first input coupled to a predetermined threshold, a signal input coupled to the signal output of the transceiver, and an output coupled to a busy signal generator. A signal strength memory unit; and coupled to the busy signal generator;
A wireless data base station system comprising: a signal detector coupled to the transceiver.