KR20010062306A - Improvements in and relating to data transmission - Google Patents

Abstract

PURPOSE: A multi-polling system for GPRS is provided to improve the polling rate in a data transmission system. CONSTITUTION: A mobile telephone network providing universal packet radio service includes a base station(2) and mobile telephones(M1-M8). The base station(2) includes a controller which not only generates the series of data packets and transmits the series to all mobiles telephones(M1-M8) through a downlink. Each data packet has a header and a payload. In the header, the configuration and length are variable, and the header includes a 1st uplink state flag for identifying a 1st selected satellite, at least one 2nd uplink state flag for identifying a 2nd selected satellite, the identification of the auxiliary uplink channel and a time slot.

Description

IMPROVEMENTS IN AND RELATING TO DATA TRANSMISSION} Data Transmission Systems, Base Stations, and Satellite Stations with Improved Polling Rates

TECHNICAL FIELD The present invention relates to data transmission systems, and in particular, to mobile telephone networks using such systems and base stations and satellite stations for use in such systems.

In mobile telephone networks, there are a number of base stations that serve different areas. Each base station is configured to communicate with a number of mobile telephones within a relevant area.

The base station communicates with the mobile phone using a number of distinct channel frequencies. Mobile telephones typically consist of groups of eight mobile telephones and send signals to all members of the group over a common downlink channel with one particular frequency assigned to the group. The base station receives signals from each of the mobile phones in the group via an uplink channel having a different specific frequency assigned to the group.

In operation, the base station transmits data in consecutive data packets over a downlink channel common to all mobile phones in each group. Each data packet consists of two parts. The first part, called the header, includes a code ID and an uplink status flag (USF), where the code ID identifies the selected mobile phone of the group, and the uplink status flag causes the mobile phone to send a data packet back to the base station. It is to. The second part contains payload data for the mobile phone to download and use as needed. The header is "transparent", ie can be read by all mobile phones in the group. The payload can be read and downloaded by the mobile phone where the payload is encrypted and only the ID is included in the header. A packet is typically 20ms in duration and when a particular phone downloads a packet containing its uplink status flag, the phone receives the packet very shortly after sending the data packet back to the base station over a common uplink channel. Will reply.

If each mobile phone receives only one uplink status flag during each period of eight consecutive data packets sent by the base station (ie, polled), then the mobile phone is only every eight 20 ms. Data may be transmitted to the base station during one 20 ms period.

It is an object of the present invention to provide an improved polling rate.

According to one aspect of the invention there is provided a data transmission system comprising a base station having a radio transmitter and a receiver and a plurality of satellite stations each having a radio transmitter and a receiver, wherein both the transmitter and the receiver of the base station have the same downlink channel. Tuned to both the transmitter of the satellite station and the receiver of the base station are tuned to a common uplink channel and at least one auxiliary uplink channel. The base station includes control means for generating a continuous data packet and transmitting it to the satellite, each data packet including a header section and a payload section. The header portion of the variable configuration and length includes a first uplink status flag identifying the first selected satellite, which causes the satellite to independently transmit data packets when this flag is received by the first selected satellite. And at least one second uplink status flag identifying a second selected satellite associated with the identity and time slot of the secondary uplink channel and transmitting to the base station via By having the selected satellite transmit the data packet alone back to the base station on the secondary uplink channel in a time slot, one data packet is used, resulting in a multi-polling effect of the satellite.

According to another aspect of the invention there is provided a base station having a radio transmitter and a receiver for communicating with a plurality of satellite stations, the transmitter being tuned to a predetermined downlink channel, the receiver being at least one auxiliary with a predetermined uplink channel. Tuned to an uplink channel, the base station includes control means for generating and transmitting a continuous data packet to each satellite station, each data packet including a header portion and a payload portion, and a header portion having a variable configuration and length One data packet including a first uplink status flag identifying a selected satellite station and at least one second uplink status flag identifying a second selected satellite station associated with the identity and time slot of the secondary uplink channel. Multipolling effect of satellite stations is obtained by using.

According to another feature of the invention there is provided a satellite station having a unique identity with a unique wireless transmitter and receiver, the receiver being tuned to a predetermined downlink channel, the transmitter being pre-set with at least one auxiliary channel. Tuned in the uplink channel, the satellite station includes control means for receiving a continuous data packet from the base station, each data packet including a header portion and a payload portion. The header portion with the variable configuration and length includes a first uplink status flag that carries the identity of the first selected satellite station so that if the identity corresponds to a unique identity, the control means causes the control means to route the data packet over the preset uplink channel to the base station. And at least one second uplink status flag that carries an identity of the secondary uplink channel and conveys the identity of the second selected satellite station associated with the time slot and controls if this identity corresponds to a particular identity. By causing the means to send the data packet back to the base station on the secondary uplink channel in a time slot, causing the satellite station to be multi-polled using one data packet.

1 is a block diagram of a base station in communication with a plurality of mobile phones;

2 shows the structure of a data packet.

Example

As shown in FIG. 1, the base station 2 simultaneously transmits data via a downlink channel of frequency f ₂ to a group of, for example, eight satellites or mobile phones M1 to M8 and transmits the data to the frequency. A wireless transmitter 4 and a receiver 6 for mainly receiving on the uplink of (f ₁ ).

The signal generated by the control device 8 and transmitted by the base station 2 includes a series of data packets each having a 20 ms period.

As shown in Fig. 2, each data packet includes a header H and a payload P. The header may include a first uplink status flag slot 12, e.g., a mobile phone, including an uplink status flag USF2 for a mode slot 10, e.g., mobile phone M2, which will be described in detail below. A second uplink status flag slot 14 comprising an uplink status flag USF3 for M3). The second uplink status flag slot is followed by a time slot 16 and a frequency slot 18 that define a time slot T3 in the auxiliary uplink channel, for example at frequency f ₃ . The payload P then follows.

In operation, when mobile phone M2 receives a packet, mobile phone M2 sends a data packet over a default uplink channel of frequency f ₁ in response to uplink status flag USF2. send. When mobile phone M3 receives the same data packet, mobile phone M3 responds to uplink status flag USF3 in a particular time slot TS ₃ via a secondary uplink channel of frequency f ₃ . Send a data packet.

In this way, the base station can receive two data packets from two mobile phones in response to the same data packet transmitted on the downlink channel. To achieve this situation, the period of header H has increased at the expense of the payload P, because the standard says that the packets should all be the same for a given system.

Although the secondary uplink channel has been defined to have a frequency of f ₃ , it will be understood that the base station can have a number of different channels of different frequencies that can be used as the secondary uplink channel. Thus, the base station may select a different secondary uplink channel in different cases depending on availability.

Also, while each packet is shown to include a second uplink status flag, the packet may include a tertiary uplink status flag or more, each accompanied by its time and frequency slot. However, such additional uplink status flags will generate returns that reduce and gradually attenuate the period of the payload.

The polling method described above is referred to below as multipolling.

The advantage of pure polling over contention-based access on Real Time (RT) traffic channels lies in the determinism of access delay. In polling, access delay is deterministic, whereas in contention-based access, access delay is stochastic, further damaging RT traffic. However, as the system load increases, the polling algorithm must search the channel space to accept a positive response from the polled mobile phone. On the other hand, in a competition-based approach, a common pool of available channels over which mobile phones compete is known.

Competition based:

As the load increases, more and more mobile phones are competing for redundancy (unused / multiplexed), which is decreasing in number. This means that as the load increases, the likelihood of failing to acquire a channel will increase, resulting in a dropped call-to-voice gap. The burden of securing a channel is placed on the mobile phone, that is, the success of the mobile phone.

Poll based:

The problem with increasing load is that rather than competing for extra time slots, it is necessary to quickly search for extra time slots to allocate channels to mobile phones. The result of not searching for a channel will be the same one faced in the case based on competition. The burden of securing the channel lies with the base station controller (BSC), ie, whether the BSC is successful.

To cope with the transitional behavior required by the polling algorithm to cope with increased load, we use fuzzy techniques that use the following general rules.

The mode slot 10 in the header is used to identify to the polled mobile phone which of the above options the base station uses.

When employing standard General Packet Radio Service (GPRS) polling-The standard GPRS MAC (General Packet Radio Service Medium Access Control) header is used to poll up to two mobile phones accommodated on each time slot.

When employing multipolling-Standard GPRS MAC headers do not provide enough flexibility to achieve multiplexing gains. Thus, multipolling allows one or more mobile phones to be polled in each time slot and the designated response channel is signaled into the MAC header.

Probabilistic multipolling is adopted when the load approaches the limit of the cell. This technique uses two statistical methods to ensure that the answering mobile phone has access to the remaining channels in a fair manner.

One . The statistical nature of speech, i.e. its exponential attenuation, gives the probability that the channel is active at time t given by P (t) = e ^-βt and the probability of remaining at time t. It is given by Q (t) = 1-e- ^βt . Where β is ...

2 . Competition is used on the answer channel, i. E. The mobile phone searches for space (time slots) within different frequency response channels and then competes with other mobile phones for that space.

In the first case, we select the channel for the response by measuring the elapsed time that the call has been in the active phase. In this way, the channel for response under high load conditions is selected among the channels that remain active for the longest and most likely become inactive the fastest. In the second case the mobile phone response time slots are grouped such that the mobile phone can compete for the selected response channel in the same manner as described above. In this way, when load increases and spare channels run short, polling will also fall fairly.

In the second case a decision will be sacrificed for flexibility. However, the decision is not completely eliminated because the way the response channel is provided is now different. Rather than providing one channel to only a given mobile phone to answer, the system provides a group of channels to allow the mobile phone to answer using any one of them.

In the General Packet Radio Service / Enhanced Data Rates for GPRS (GPRS / EDGE) standard, a Packet Control Acknowledgment is transmitted in response to a Radio Resource (RR) message. The RR message is signaled to the mobile phone by setting the PayloadType field in the MAC header to control. The Relative Reserve Block Period (RRBP) field in the MAC header is used to indicate to the mobile phone when it is expected to respond to the system with a packet control acknowledgment signal. The Supplementary Polling (SP) bit indicates the validity of this field.

When a GPRS / EDGE mobile phone requests voice service, it is placed in a polling group if it is silent phase, or given a channel if it is active. The RR message that such a mobile phone may be interested under in this environment is the reallocation of the RR message channel when it is active. The design of the multipolling header allows this in the response field (see the response encoding section above). For this reason, the RRBP and SP fields may be removed from the multipolling header when one or more mobile phones are polled in a given time slot.

Concrete Syntax Notation 1 (CSN1) coding on a multi-polling header is described below. The header length depends on the value of the first two bits in the header because the value of these bits selects the subsequent MAC structure. The definition of the structure is also described below.

As for the single mobile phone architecture, the MAC header is the same as for the standard GPRS MAC header, as long as the header includes the SP, RRBP, and Payload Type fields.

In terms of subsequent structure, only the Payload Type is kept from the standard header. The reason for the removal of the RRPB and SP bits has been described above. However, the payload type needs to be included because the payload type signals an automatic response to radio resource (RR) control messaging.

The length of the polling code depends on the number of mobile phones being polled. This is described in detail in the Polling Code section. The length of the response field depends again on the number of mobile phones polled. The structure of the response field is described above in the Response Encoding section.

Possible code to occupying the mode slot 10 in the header is as follows:

The code occupying slot 12 is as follows:

Depending on whether two, three or four mobile phones are polled, slot 14 is occupied by one of the following three options.

When using the option, slots 16 and 18 in the header are occupied by:

The present invention enables multiple polling of satellites using one data packet and provides an improved polling rate.

Claims (18)

In a data transmission system, A base station having a radio transmitter and a receiver, and a plurality of satellite stations each having a radio transmitter and a receiver, Both the transmitter of the base station and the receiver of the satellite station are tuned to the same downlink channel, Both the transmitter of the satellite station and the receiver of the base station are tuned to a common uplink channel and at least one auxiliary uplink channel, The base station has control means for generating a succession of data packets and transmitting them to the satellite station, Each data packet has a header section and a payload section, The header portion of varying configuration and length identifies a first selected satellite station and, when received by the first selected satellite station, causes the satellite station to independently send a data packet back to the base station over the uplink channel. At least one second uplink status flag having a link status flag and identifying a second selected satellite station associated with an identity and a time slot of the secondary uplink channel; Further having the at least one second uplink status flag for causing a selected satellite station to send a data packet to the base station via the secondary uplink channel alone in the time slot; A single data packet is used to enable multi-polling of the satellite station. Data transmission system. The method of claim 1, The control means is configured to combine a code indicating the need for single polling, multipolling or probabilistic multipolling into the header of each data packet, Each satellite station adapts itself to the requirements upon receipt of the code. Data transmission system. The method of claim 2, When the header includes a code indicating a single polling, the control means includes a 3-bit polling code, a 1-bit S / P code, a 2-bit RRPB code, and a 2-bit payload type code for each of the data packets. Configured to bind to the header of the Data transmission system. The method of claim 2, When the header of each data packet includes a code indicating multipolling, the control means is configured to combine a polling code, a 2-bit payload type code and a response field: response field structure code to the header. Data transmission system. The method of claim 4, wherein The length of the polling code is (x + 3) bits when x satellites are being polled, and the response field: length of the response structure code is x bits. Data transmission system. The method of claim 5, The control means is arranged to configure the header such that the response field structure comprises a 3-bit USF, a 2-bit response time slot and a 2-bit response frequency. Data transmission system. The method according to any one of claims 1 to 6, Each said satellite comprising said uplink and downlink channels forming part of a mobile telephone and wireless telephone network. Data transmission system. A base station having a radio transmitter and a receiver for communicating with a plurality of satellite stations, The transmitter is tuned to a predetermined downlink channel, The receiver is tuned to a predetermined uplink channel and at least one auxiliary uplink channel, The base station has control means for generating a continuous data packet and transmitting it to the satellite station, Each data packet has a header portion and a payload portion, The header portion of varying configuration and length holds at least one second uplink state, the first uplink status flag identifying a first selected satellite station and identifying a second selected satellite station associated with an identity and time slot of the secondary uplink channel. Holds the link status flag, To enable multipolling of the satellite stations using a single data packet. Base station. The method of claim 8, The control means is configured to couple a code to the header of each data packet indicating whether single polling, multipolling or stochastic multipolling is required. Base station. The method of claim 9, When the header includes a code indicating a single polling, the control means includes a 3-bit polling code, a 1-bit S / P code, a 2-bit RRPB code, and a 2-bit payload type code for each of the data packets. Configured to bind to the header of the Base station. The method of claim 9, When the header of each data packet includes a code indicating multipolling, the control means is configured to combine a polling code, a 2-bit payload type code and a response field: response field structure code to the header. Base station. The method of claim 11, The length of the polling code is (x + 3) bits when x satellites are being polled, and the response field: length of the response structure code is x bits. Base station. The method of claim 12, The control means is arranged to configure the header such that the response field structure comprises a 3-bit USF, a 2-bit response time slot and a 2-bit response frequency. Base station. A base comprising the base station according to claim 8. Telephone network. A satellite station having a radio transmitter and a receiver and having a unique identity, The receiver is tuned to a predetermined downlink channel, The transmitter is tuned to a predetermined uplink channel and at least one auxiliary uplink channel, The satellite station has control means for receiving a continuous data packet from a base station, Each data packet has a header portion and a payload portion, The header portion of variable configuration and length is a first uplink status flag that carries the identity of the first selected satellite station, and if the identity corresponds to the unique identity, causing the control means to send a data packet over the predetermined uplink channel. At least one second uplink status flag that holds the first uplink status flag to be sent back to the base station and carries the identity of the second selected satellite station associated with the identity and time slot of the secondary uplink channel; The at least one second uplink causing the control means to send a data packet back to the base station over the secondary uplink channel in the time slot if the identity of the second selected satellite station corresponds to the unique identity. It also holds a state flag, Cause the satellite station to be polled using a single data packet satellite. The method of claim 15, The header of each said data packet includes a code indicating whether single polling, multi polling or stochastic multipolling is required, The control means adapts itself to the requirements upon receipt of the code. satellite. The method of claim 16, When the header includes a code indicating a single poll, the control means is configured to generate a 3-bit polling code, a 1-bit S / P code, a 2-bit RRPB code, and a 2-bit payload type code for each of the data packets. Configured to bind to the header of the satellite. 17. A satellite station according to any one of claims 14 to 16, comprising Mobile phone.