CN1113494C - Wireless resource distribution method - Google Patents

Abstract

The invention discloses a method for allocating wireless resources based on a TDMA wireless system. The wireless channel in the system is a periodic cycle multi-frame, and multiple mobile stations (MS) need to occupy the same wireless channel. The method is as follows: assign each MS Several wireless channels, a temporary block flow start time and a fixed-length allocation bit table, the number of bits in the allocation bit table is the smallest unit of wireless resources that can be used by MS in each multiframe period of the wireless channel Each bit (bit) corresponds to the minimum unit radio resource that can be used by the MS in the multiframe period, and its bit value enables the use of the corresponding minimum unit radio resource.

Description

A method for allocating wireless resources

The present invention relates to a method for allocating wireless resources in a mobile communication system, specifically a method based on a TDMA wireless system, the wireless channel of which is a periodic cycle multi-frame, and there are multiple mobile stations (MS) that need to occupy the same wireless channel Radio resource allocation method.

Data communication technology and mobile communication technology are two very active directions in the field of information technology today. Wireless data service is a combination of data communication technology and mobile communication technology. The support for IP and high-speed data service has become the evolution of the second generation mobile communication system. direction. GPRS (General Packet Radio Service: General Packet Radio System) is a packet-switching-based data service provided by GSM Phase 2+. It is a system that implements packet transmission mode on PLMN (Public Land Mobile Network: Public Land Mobile Network). GPRS will provide people with services such as Internet access, e-commerce, sending and receiving Email, automotive electronics, and so on. GPRS completes the packet transmission function by adding a series of functional entities on the basis of the original GSM network. GPRS retains the division of the wireless subsystem (BSS) and the network subsystem (NSS). For the network subsystem, GPRS adds SGSN and GGSN two functional entities, as for the wireless subsystem, it is shared with the GSM circuit switching service. In the wireless subsystem, a wireless channel type PDCH (packet data logical channel) is added, which is mainly used for the transmission of GPRS packet data and signaling. Specifically, there are logical channels such as PBCCH (packet broadcast control channel), PCCCH (packet common control channel), PDTCH (packet data traffic channel: Paeket Data Traffic Channel), PACCH (packet associated control channel), PTCCH/D and PTCCH/U Type, independent allocation of uplink and downlink wireless channels. When there is data transmission, a Temporary Block Flow (TBF: Temporary Block Flow) needs to be established. TBF is a physical connection composed of PDCH that unidirectionally transmits LLC PDUs between two radio resource management entities (RR) entities. It consists of one or more PDCHs and is released when the current transmission service ends.

At this stage, the GPRS specification formulated by ETSI (European Telecommunications Standardization Institute: European Telecommunications Standardization Institute) defines three MAC modes: fixed allocation, dynamic allocation and extended dynamic allocation, allowing a mobile station (MS) to simultaneously use multiple wireless channels, multiple MSs share a wireless channel.

For uplink dynamic allocation, the implementation strategy is that the base station subsystem (BSS) specifies one or several channels for the MS when assigning wireless resources, and each channel has a USF (Uplink State Flag: Uplink State Flag ) value, the USF values of different MSs on the same channel are different. The network controls the MS to transmit data on the radio block (Radio Block) on the uplink PDTCH by sending different USF values on the downlink PDTCH. The MS starts to monitor the USF on PDTCH/D at the specified TBF Starting Time, and once it finds its own USF value, it can transmit data on the corresponding uplink RADIO BLOCK.

For uplink extended dynamic allocation, the difference between it and dynamic allocation is that the network specifies a group of channels for the MS, assigns a USF value to each channel, and numbers the channels from low to high. When the MS receives the USF value on a certain channel, it assumes that the uplink radio block corresponding to the channel and the corresponding radio blocks on the channel with a higher number than the channel are used by itself. The improvement is that the MS does not need to monitor the USF values on all channels every time.

Obviously, although dynamic allocation and extended dynamic allocation can better solve the multiplexing situation of multiple MSs on one channel, it is at the cost of MS having to monitor the transmission of the downlink channel USF at all times, and the network side has no downlink channel. An empty RLC/MAC packet must also be sent during data transmission to carry the USF value, which increases unnecessary power consumption of the MS and BTS and limits the measurement of the MS.

For uplink fixed allocation, its implementation strategy is that when assigning radio resources, BSS assigns one or more channels for MS, and specifies a TBF start time and an allocation bit table. The allocation bit table is a continuous bit field of a certain length, and the value of each bit is 1 or 0. If it is 0, the MS cannot use the radio block specified by this bit; if it is 1, the MS can use the radio block specified by this bit.

The wireless block specified by each bit is different according to the meaning of the BLOCKS_OR_BLOCK_PERIODS field in the assignment message. If the BLOCKS_OR_BLOCK_PERIODS field indicates a BLOCK, each bit in the allocation bit table corresponds to a BLOCK on a channel, and which channel the BLOCK corresponds to can be determined according to an algorithm, which will not be described in detail here; if the BLOCKS_OR_BLOCK_PERIODS field indicates If it is BLOCK PERIODS, this bit corresponds to all wireless blocks within the BLOCK PERIODS time period on all channels assigned to the MS. The following example illustrates:

Assume that the channels designated by the network for the MS are 0, 1, and 2, the allocation bit table is three bits long, and the value filled in the allocation bit table is "101". If the BLOCKS_OR_BLOCK_PERIODS field indicates BLOCK, the MS can only transmit one block on channels 0 and 2, and a total of 2 blocks; 2 blocks are transmitted for a total of 6 blocks.

The advantage of fixed allocation is that the MS does not need to monitor the downlink PDCH channel all the time, and can directly send data on the BLOCK of the specified channel. However, fixed allocation is difficult to control the multiplexing of multiple MSs on the same channel, because the allocation bit table of each MS corresponds to which RADIO BLOCK on the wireless channel is determined by the two parameters of TBFStarting Time and BLOCKS_OR_BLOCK_PERIODS field, when TBFStarting When Time uses the absolute frame number, it can be calculated according to the BLOCKS_OR_BLOCK_PERIODS field that the MS occupies a certain RADIO BLOCK, but the network needs to accurately maintain the information that multiple MSs occupy the RADIO BLOCK on the same channel, so that multiple MSs can be multiplexed on the same PDCH without causing conflict. However, each MS has different TBF Starting Time values, BLOCKS_OR_BLOCK_PERIODS fields, and different allocation bit table lengths. It will be quite difficult for the network to maintain such information.

In addition, since the length of the allocation bit table can be long or short (the maximum length is determined by the number of remaining bits in the control block), it is difficult for the network to control the timing of confirmation. If the allocation bit table is too short, the network must frequently transmit PACKET UPLINK ACK/NACK message, in order to re-assign the resources allocated last time for the MS, this frequent transmission will inevitably lead to waste of RADIO BLOCK; if the allocation bit table is too long, the MS fails to receive the PACKET UPLINK ACK/NACK message from the network If there is repeated assignment information in the MS, then the MS will waste at least one radio block specified in the allocation bit table. The longer the allocation bit table is, the more radio blocks will be wasted.

Therefore, the object of the present invention is to propose a wireless resource allocation method based on a TDMA wireless system, the wireless channel of which is a periodic cycle multi-frame, and there are multiple mobile stations (MS) that need to occupy the same wireless channel.

A further object of the present invention is to propose an extended fixed-allocation radio resource allocation method based on the General Packet Radio Service (GPRS) system, so as to overcome the defects of both the above-mentioned fixed allocation and dynamic allocation strategies.

The object of the invention is achieved through the following technical solutions:

A method for allocating radio resources based on a TDMA wireless system, the radio channel in the system is a periodic cycle multiframe, and a plurality of mobile stations (MS) need to occupy the same radio channel, characterized in that the allocating method for radio resources is:

Specify at least one wireless channel, a temporary block flow start time (TBFStarting Time) and a fixed-length allocation bit table for each mobile station (MS), wherein, the number of bits (bits) in the allocation bit table is the number of bits per radio channel The quantity of all the smallest unit radio resources that can be used by the mobile station (MS) in a multiframe period, and each bit (bit) corresponds to the smallest unit radio resource that can be used by the mobile station (MS) in the multiframe period, which The bit value enables use of its corresponding minimum unit radio resource.

According to the above technical solution, when the wireless system is a general packet radio service (GPRS) system, its packet data channel (PDCH) has a multiframe period of 52, and each multiframe period can be used by the mobile station (MS) The minimum unit of radio resources is 12 (B0-B11) radio blocks (RADIO BLOCK), and its MAC access mode is an extended fixed allocation method:

Specify several wireless channels, a temporary block flow start time (TBF StartingTime) and a fixed-length 12-bit allocation bit table for each mobile station (MS). Each bit in the allocation bit table corresponds to 52 multiframes respectively. 12 radio blocks (RADIO BLOCK);

When the bit value is 1, the mobile station (MS) can use its corresponding radio block (RADIO BLOCK), if it is 0, the mobile station (MS) cannot use its corresponding radio block (RADIO BLOCK); and

The BLOCKS_OR_BLOCK_PERIODS field in the assignment message is specified as BLOCK PERIODS.

The above minimum unit wireless resource may also not be a wireless block, for example, it may be one or more burst sequences.

Furthermore, based on the first assignment, one or more multiframe periods may be regarded as a cycle, and the allocated bit table may be cyclically used to cyclically occupy the allocated radio resources.

Because the TDMA system is a time-division multiple access system, in the TDMA-based wireless communication system, the wireless path adopts the time-division multiple access method, and each mobile terminal can occupy different wireless channels at the same time, and different mobile terminals can also occupy time-sharing channels. the same wireless channel. Each channel (frequency point) is defined as a TDMA frame, and multiple TDMA frames form a multiframe, and the multiframe is used as a unit for cyclic transmission. The radio resource allocation method of the present invention can be applied to any TDMA-based wireless system, combines the advantages of fixed allocation and dynamic allocation, can greatly increase the multiplexing quantity of MSs on a wireless channel, and is convenient for system control and avoids waste of resources.

The present invention will be described in further detail below in conjunction with specific embodiments.

Take the General Packet Radio Service (GPRS) system based on the TDMA wireless system as an example. Among the three MAC access modes of GPRS, fixed allocation, dynamic allocation, and extended dynamic allocation, the network can easily control multiple MSs to multiplex on the same channel during dynamic allocation, while fixed allocation does not require MS to continuously monitor the downlink PDCH. There is also no need to continuously send USF values on the downlink PDCH. An extended fixed wireless resource allocation method of the present invention combines the advantages of the two to achieve better resource allocation. This strategy is described in detail below:

During fixed allocation, specify several channels, TBF Starting Time, and a fixed-length 12-bit allocation bit table for each MS, where the BLOCKS_OR_BLOCK_PERIODS field is specified as BLOCKPERIODS. Each bit in this allocation bit table corresponds to B0-B11 blocks in the 52-multiframe. When the bit is set to 1, it means that the MS can use the RADIO BLOCK. If it is set to 0, it means that the MS cannot use the RADIO BLOCK. The PDCH channel of the GPRS system is cyclically transmitted in a period of 52 multiframes. The following example illustrates:

Assume that the channel assigned by the assignment message to MS1 is 0, 1, and 2, the allocation bit table is "110111000111", and the TBF Starting Time is any suitable value (it can be an absolute frame number or a relative frame number), and the bits in the allocation bit table are given by High to low correspond to B0-B11 of 52 multiframes respectively. If the BLOCK corresponding to the frame number indicated by TBF Starting Time is not exactly B0, but one of the RADIO BLOCKs (assumed to be B3), then MS1 can be on channels 0, 1, and 2 in the first 52 multiframe periods. Each of B4, B5, B9, B10, and B11 transmits one wireless block, and each subsequent 52-multiframe cycle can be transmitted on B0, B1, B3, B4, B5, B9, and B10 on channels 0, 1, and 2. , B11 each transmit a BLOCK. During the data transmission process, the network does not need to confirm, and MS1 uses the allocation bit table cyclically according to the 52-multiframe period until the TBF is released (normally or abnormally). In the process of MS1 data transmission, if the network wants to order MS2 to multiplex to this channel, it only needs to avoid the situation that the same position in the 12 bits is "1" when determining the allocation bit table. For example, the allocation bit can be assigned to MS2 Table "001000111000", regardless of TBF Starting Time. Afterwards, the network only needs to "OR" the allocation bit table of each MS to determine the RADIO BLOCK that the MS can use later. In the limit case, one channel can be used by 12 MSs at the same time.

The advantages of this method are:

1. Once assigned, the RADIO BLOCK occupied by the MS can be determined. After that, the MS does not need to continuously monitor the downlink channel, and the network does not need to continuously send data on the downlink channel.

2. After a TBF is established, the network does not need to rely on the PACKET UPLINK ACK/NACK message to repeatedly allocate resources for the MS, unless the network needs to change the current allocation.

3. It can overcome the multiplexing of multiple MSs in the same wireless channel which is difficult to control in the original fixed allocation.

Furthermore, the network can adopt a certain strategy to control how many 52-multiframe cycles each MS uses to allocate the bit table, so that the number of MSs that can be multiplexed on a PDCH will increase greatly. This situation applies to the situation where the network load is heavy, the number of PDCHs is small, and the QoS required by the MS is not high.

The resource allocation method is not limited to the GPRS system. As long as it is a TDMA system, the wireless channel has the concept of multi-frame period, and there is a demand for multiple MSs to occupy the same wireless channel, the method of the invention can be used to allocate wireless resources for MSs. It's just that the bits in the allocation bit table are not necessarily 12, but the number of the smallest unit of radio resources that can be used by the MS in each multiframe period of the radio channel. Each bit does not necessarily correspond to a BLOCK PERIODS, but a minimum unit of radio resources that can be used by the MS.

Claims (3)

1, a kind of wireless resource allocation methods based on the TDMA wireless system, the wireless channel in this system is the periodic cycle multi-frame, and a plurality of travelling carriage need take same wireless channel, it is characterized in that this wireless resource allocation method is:

Specify the distribution bit table of at least one wireless channel, a Temporary Block Flow time started and a regular length for each travelling carriage, wherein, figure place in this distribution bit table is that all can be moved the quantity of the least unit Radio Resource of platform use to wireless channel in each multiframe period, and each can be moved the least unit Radio Resource that platform uses in corresponding respectively multiframe period, and its place value is the use that enables its corresponding least unit Radio Resource.

2, wireless resource allocation methods according to claim 1, it is characterized in that described wireless system is a General Packet Radio Service System, its Packet Data Channel was 52 multiframe periods, the least unit Radio Resource is 1 radio block, the quantity that can be moved the radio block of platform use in each multiframe period is 12, then described distribution method is the fixed allocation MAC cut-in method of expansion, comprising:

For each travelling carriage is specified several wireless channels, a Temporary Block Flow time started and the distribution bit table that regular length is 12 bits, 12 radio blocks in corresponding 52 multi-frames of each bit difference in this distribution bit table;

When the bit place value was 1, travelling carriage can use its corresponding radio block, if 0, then travelling carriage can not use its corresponding radio block; And

BLOCKS_OR_BLOCK_PERIODS is appointed as in the territory BLOCK PERIODS in the assignment message.

3, wireless resource allocation methods according to claim 1 and 2 is characterized in that further comprising: by being one or more multiframe periods a cycle period, recycle described distribution bit table.