Method for allocation of radio resources for a data transmission in a radio communication system

Radio communication systems serve to transmit information, voice or data, by means of electromagnetic waves via a radio interface, also called an air interface, between a transmitting and a receiving radio station. An example of a radio communication system is the known GSM mobile radio system and its further development with the packet data service GPRS or EDGE whose architecture is described in B., for example. Walke, mobile networks and their protocols, Volume 1, Teubner-Verlag Stuttgart, 1998, pages 138 to 151 and pages 295 to 311 described. In this case, a channel formed by a narrow-band frequency range and a time slot is provided for transmitting a subscriber signal. Since a subscriber signal in a channel differs in frequency and time from the other subscriber signals, the radio station can perform a detection of the data of the subscriber signal. In newer radio communication systems, such as the UMTS system, the individual participants are also distinguished by different spreading codes.

In the case of packet-switched data transmission, the data transmission for several subscribers takes place via one and the same physical channel. In currently common GPRS or EDGE systems, a plurality of, for example six physical channels, referred to as packet data channels, are provided for the packet-switched data transmission. Each participant can also occupy several of these packet data channels simultaneously (multislot). Per subscriber, a packet data flow (Temporary Block Flow TBF) is broken down into time-limited radio blocks, which are transmitted. Various modulation / coding schemes are used for error protection. The possible modulation / coding schemes differ with regard to the division of the radio block into payload and error protection information. Depending on the set modulation / coding scheme, these radio blocks have different payloads for the same length. Depending on the radio conditions, a connection is assigned a modulation / coding scheme with higher or lower error protection. In poor radio conditions, a modulation / coding scheme with higher error protection and in good radio conditions is assigned a modulation / coding scheme with less error protection. Since the proportion of the payload differs depending on the set modulation / coding scheme, the achievable data rate also differs.

For packet data switching, a radio communication system includes, for example, a GSM mobile radio network with GPRS, a plurality of Serving GPRS Support Nodes (SGSNs) which are networked with each other and which provide access to a fixed data network. The packet data service nodes are also connected to base station controllers (BSC). Each base station controller in turn allows a connection to at least one base station (BTS) and makes the management of the radio resources of the connected base stations. To manage the radio resources for packet-switched data transmissions, the base station controller comprises a Packet Control Unit (PCU). A base station is a transmitting / receiving unit that can establish a communication link to a mobile terminal via a radio interface. The allocation of the individual subscribers to a channel for a packet-switched data transmission takes place via the packet data control unit.

After arrival of the data in the packet data control unit PCU they are transmitted via the so-called Abis interface to the base station, coded there and sent via the air interface to the mobile station. The A_toInterface is a PCM30 connection with a data rate of 64 Kbps, which is divided into four subchannels of 16 Kbps each. On the A_toInterface is thus transmitted per time slot a data packet of constant length. Since a subscriber on the radio interface, depending on the used modulation / coding scheme, a different user data rate is available, is on the A_toInterface for the further transmission of this data depending on the modulation / coding scheme used a different amount of time slots required. In order for a subscriber who receives a high data rate via the radio interface to be able to use this high data rate, the A_toInterface according to sufficient time slots can be assigned. One way to avoid a bottleneck in this assignment is to use the A_toInterface is designed so that each participant, regardless of the modulation / coding scheme actually used the number of time slots required for the highest data rate is reserved. However, this leads to poor utilization of the line capacity.

The invention is therefore based on the problem to provide a method for allocating radio resources for a packet-switched data transmission, on the one hand satisfactory data rates for all participants are guaranteed and on the other hand, the existing infrastructure resources are effectively used.

This problem is solved by a method according to claim 1. Further embodiments of the invention will become apparent from the dependent claims.

In the method, resources to be allocated for a subscriber are determined jointly on a first interface between a terminal and a first network node and on a second interface between the first network node and a second network node. In this case, both a data rate requested by the subscriber and transmission characteristics of the first interface, as well as a relationship between resources to be allocated on the first interface and resources to be allocated to the second interface are taken into account. It also takes into account which resources have already been allocated to other subscribers. Finally, the benefit of all participants is optimized. In the method according to the invention, since the resources on the first interface and the second interface are assigned jointly, taking into account the relationship between the resources required on the first interface and the resources required on the second interface, and at the same time optimizing the use of all the participants, On the one hand, a satisfactory data rate is guaranteed for all subscribers and, on the other hand, the existing infrastructure resources are effectively allocated. The fact that already existing allocations of other subscribers are taken into account has an advantageous effect on the computation time and processor performance required for the allocation.

According to a preferred embodiment, the first interface is designed as a radio interface between a mobile terminal and a network-side radio station, which forms the first network node. On the first interface, packet data channels and modulation and coding schemes are assigned. One or more time slots are allocated on the second interface, wherein the number of allocated time slots depends on the data rate realized on the first interface. The data rate realized on the first interface depends on the assigned coding scheme and the transmission characteristics of the first interface. This embodiment of the inventive method is for the allocation of resources on the radio interface between mobile terminal and base station and the A_toInterface between base station and base station controller in a GSM / GPRS / EDGE system.

When allocating elements on the packet data channels, it is preferably taken into account on how many channels the terminal can simultaneously transmit or receive. When determining the elements to be allocated on the packet data channels, only elements on at most as many packet data channels are considered as corresponds to the number of channels on which the terminal can simultaneously transmit or receive. As a result, allocation options that the terminal can not use anyway, discarded from the outset. This saves processing time.

The quotient of the actual data rate and the data rate requested by the subscriber is preferably defined as the benefit of a subscriber. The benefit of all subscribers is then defined as the minimum of the quotients of the actual data rate and the data rate requested by the subscriber for all subscribers. Preferably, the benefit of all subscribers is optimized in the sense that the benefit of all subscribers is maximized. This means that the smallest quotient for a subscriber is maximized from the actual data rate and the data rate requested by the subscriber. This ensures that all participants receive the same share of the data rate they demand.

If a minimum data rate is predetermined for a subscriber which should not be undershot during the data transmission from and to the subscriber, it is within the scope of the invention to consider this minimum data rate for this subscriber as a boundary condition in the optimization of the benefit of all subscribers. This ensures that this subscriber receives the minimum data rate necessary for the functioning of his service even in high traffic.

It is within the scope of the invention to check for the subscriber to which number of packet data channels the elements to be allocated are distributed. For all plausible combinations of coherent packet data channels that correspond to the determined number, then an assignment for the subscriber is examined and the benefit of all participants is determined. The subscriber is then assigned the combination of contiguous packet data channels for which the greatest benefit of all participants results. The benefit of all participants can be determined mathematically exactly, for example by linear optimization. This procedure thus combines a mathematically exact solution of the assignment problem with a heuristic approach for the probably most favorable time slots to be allocated on the second radio interface.

In the following the invention with reference to the figures and an example will be explained in more detail.

Figure 1 shows a section of the architecture of a GSM / GPRS / EDGE system.

Figure 2 shows a flow chart for the allocation of resources for a new subscriber.

A radio communication system (see FIG. 1) comprises a multiplicity of base stations BTS via which a radio link can be established via a radio interface Um to a mobile terminal MS. The base station BTS is via an A_toInterface connected to a base station controller BSC. The base station controller BSC is connected via an A_subInterface connected to a transcoding and rate adaptation unit TRAU, which is connected via an A-interface with a mobile switching center MSC. The mobile switching center MSC provides the connection to other networks, for example to the fixed network. About the A_toInterface, the A_subInterface and the A-interface are transmitted circuit-switched data.

In the base station subsystem BSS formed of the base station BTS and the base station controller BSC, there is a packet data control unit PCU which may be mounted, for example, on the base station controller BSC. The packet data control unit PCU is responsible for the switching of packet-switched data and is on the one hand via the A_toInterface connected to the base station and on the other hand, for example via a G_bInterface with a packet data service node SGSN, via which a connection to a packet data network, for example the IP network, is realized. On the radio interface U_m packet data channels PDCH are set up, via which a packet-switched data transmission is realized. For packet-switched data transmission, different modulation and coding schemes are available in the GPRS system and in the EDGE system, which differ in terms of their error protection. Modulation / coding schemes that provide high error protection are at a lower data transfer rate, and modulation / coding schemes that provide low error protection are associated with a higher data transfer rate. Depending on the transmission conditions on the air interface and the requirements of a subscriber regarding the data rate, a connection is assigned by the packet data control unit PCU to a suitable modulation / coding scheme. The actually achieved data rate depends on the one hand on the modulation / coding scheme used and on the other hand on the number of required retransmission rates and is determined on the basis of radio planning tables or measurements.

In one embodiment, let the number of packet data channels be K, to which N packet-switched data transmissions of N subscribers are to be allocated. Each packet data channel can be assigned more than one subscriber, but not more than a maximum number N_Max, In the GSM system, up to 16 subscribers can be allocated to a packet data channel. This implies 1 <= N_Max <= 16.

Here, a subscriber may be assigned items on more than one packet data channel if the subscriber's terminal is capable of transmitting or receiving on multiple channels simultaneously. This property is called a multislot capability. In today's GSM systems it is common that in this case the subscriber is assigned elements on contiguous channels, ie channels with consecutive numbering.

When connecting, a subscriber i requests a target data rate R_i^* which should be achieved as far as possible. Furthermore, the subscriber i gives a minimum data rate_Ri^min on, which should not fall below for the data transfer. Examples of this are video streams, where a transmission no longer makes sense, should a minimum rate can not be guaranteed. In fact, the subscriber receives the data rate R_iwhich depends on the transmission characteristics of the radio channel, the utilization of the network and the resources allocated to the subscriber. The physical propagation conditions, such as the distance between the mobile terminal and the base station, shading effects or the interference situation, and the applicable modulation / coding schemes, are included here. The data rate that a subscriber i can receive if he could exclusively use a physical channel is included <i>S</i><maths id="math0001" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext mathvariant="italic">c</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></mfrac></mrow></math><img file="EP1453339A1_D0001.tif" /></maths> and depends on the applied modulation / coding scheme C.<maths id="math0002" num=""><math display="block"><mrow><mtext>{</mtext><msubsup><mrow><mtext mathvariant="italic">S</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow><mrow><mtext mathvariant="italic">c</mtext></mrow></msubsup><mtext> : </mtext><mtext mathvariant="italic">C</mtext><mtext> = </mtext><mtext mathvariant="italic">MCS</mtext><mtext> -1,... ,</mtext><mtext mathvariant="italic">MCS</mtext><mtext> - 9} .</mtext></mrow></math><img file="EP1453339A1_D0002.tif" /></maths> The actual data rate R_i thus depends on the assigned modulation / coding scheme C. Furthermore, it depends on the proportion p_{i, j} subscriber i receives on channel j due to the assignment. It applies<maths id="math0003" num=""><math display="block"><mrow><mtext mathvariant="italic">0</mtext><mtext> ≤ </mtext><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">i, j</mtext></mrow></msub><mtext> ≤ 1, (1 ≤ </mtext><mtext mathvariant="italic">i</mtext><mtext> ≤ </mtext><mtext mathvariant="italic">N</mtext><mtext>,1 ≤ </mtext><mtext mathvariant="italic">j</mtext><mtext> ≤ </mtext><mtext mathvariant="italic">K</mtext><mtext>)</mtext></mrow></math><img file="EP1453339A1_D0003.tif" /></maths><maths id="math0004" num=""><img file="EP1453339A1_D0004.tif" /></maths> means that the participant i a share p_{i, j} has been assigned j on the packet data channel.

For a given modulation / coding scheme C and the sizes S^c and p_{i, j}, is the actual data rate for the subscriber i<maths id="math0005" num=""><img file="EP1453339A1_D0005.tif" /></maths>

Depending on the utilization of the system and the radio field conditions, the actual data rate <i>R</i>_<i>i</i> greater than, equal to, or less than the target data rate required by subscriber i <i>R</i><maths id="math0006" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>*</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></mfrac></mrow></math><img file="EP1453339A1_D0006.tif" /></maths> his. A measure of the satisfaction of the participant i is the benefit U_i of the participant i, which is defined as follows:<maths id="math0007" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></msub><mtext> := </mtext><mfrac><mrow><msub><mrow><mtext mathvariant="italic">R</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></msub><mtext></mtext></mrow><mrow><msubsup><mrow><mtext mathvariant="italic">R</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow><mrow><mtext>*</mtext></mrow></msubsup></mrow></mfrac><mtext>.</mtext></mrow></math><img file="EP1453339A1_D0007.tif" /></maths>

With the method for allocating resources, the assignment matrix (p_{i, j}) determining the utility U_i for all participants<maths id="math0008" num=""><math display="block"><mrow><mtext mathvariant="italic">i</mtext><mtext> ∈ {1,...,</mtext><mtext mathvariant="italic">N</mtext><mtext>}</mtext></mrow></math><img file="EP1453339A1_D0008.tif" /></maths> optimized. Since it is not possible to use U_i for a participant i increase without the benefit U_k For all other participants to reduce k, the benefit of all participants is defined and optimized. The benefit U of all participants is defined as follows<maths id="math0009" num=""><math display="block"><mrow><mtext>U = </mtext><mtext mathvariant="italic">F</mtext><mtext>(</mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>,..,</mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext mathvariant="italic">N</mtext></mrow></msub><mtext>) :=</mtext><mtext mathvariant="italic">min</mtext><mtext>{</mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>, ...,</mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext mathvariant="italic">N</mtext></mrow></msub><mtext>).</mtext></mrow></math><img file="EP1453339A1_D0009.tif" /></maths>

In optimizing the utility of all subscribers U, the benefit of subscriber i who maximizes the least utility U is thus maximized_i having. This takes into account that the requested target data rate of each participant is different. In mathematical terms, this means maximize the function<maths id="math0010" num=""><math display="block"><mrow><mtext>(</mtext><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">i, j</mtext></mrow></msub><mtext>)→</mtext><msub><mrow><mtext mathvariant="italic">Min {U</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>(</mtext><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">i, j</mtext></mrow></msub><mtext>),...,</mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext mathvariant="italic">N</mtext></mrow></msub><mtext>(</mtext><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">i, j</mtext></mrow></msub><mtext>)}, ie</mtext></mrow></math><img file="EP1453339A1_D0010.tif" /></maths><maths id="math0011" num=""><img file="EP1453339A1_D0011.tif" /></maths> with the boundary conditions<maths id="math0012" num=""><img file="EP1453339A1_D0012.tif" /></maths>    <i>R</i>_<i>i</i> ≥ <i>R</i><maths id="math0013" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext mathvariant="italic">min</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></mfrac></mrow></math><img file="EP1453339A1_D0013.tif" /></maths>  for all participants 1 &lt;= i &lt;= N.

The value V of the optimal allocation matrix (p_{i, j}) is defined as follows<maths id="math0014" num=""><img file="EP1453339A1_D0014.tif" /></maths>

As long as i applies to all participants<maths id="math0015" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">R</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow></msub><mtext> ≥ </mtext><msubsup><mrow><mtext mathvariant="italic">R</mtext></mrow><mrow><mtext mathvariant="italic">i</mtext></mrow><mrow><mtext>min</mtext></mrow></msubsup></mrow></math><img file="EP1453339A1_D0015.tif" /></maths> applies<maths id="math0016" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext> = </mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><mtext> =...= </mtext><msub><mrow><mtext mathvariant="italic">U</mtext></mrow><mrow><mtext mathvariant="italic">N</mtext></mrow></msub><mtext>.</mtext></mrow></math><img file="EP1453339A1_D0016.tif" /></maths>

When determining the assignment matrix, the following additional boundary conditions must be taken into account: The number of time slots on which the mobile terminal can send or receive is generally smaller than the number k of packet data channels PDCH. Furthermore, one and the same packet data channel PDCH can only have a limited number N_Max Be assigned to participants. Finally, there are only a limited number of time slots on the A_toInterface, so that possibly not every modulation / coding scheme can be applied. The applicable modulation / coding schemes depend on the current assignment of the A_toTime slots to the packet data channels and the number of currently unused A_to-Channels.

The problem of the maximum number N_Max the subscribers to which one and the same packet data channel can be assigned is introduced by introducing a new boundary condition for p_ij solved:<maths id="math0017" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">i, j</mtext></mrow></msub><mtext> ≥ </mtext><mfrac><mrow><mtext>1</mtext></mrow><mrow><msub><mrow><mtext mathvariant="italic">N</mtext></mrow><mrow><mtext>Max</mtext></mrow></msub></mrow></mfrac><mtext>.</mtext></mrow></math><img file="EP1453339A1_D0017.tif" /></maths>

If N subscribers have already been allocated to the available packet data channels PDCH, and if a new connection for a new subscriber N + 1 is to be established, then appropriate boundary conditions ensure that the already allocated subscribers retain their current assignment to the packet data channels. Let a participant i on the packet data channels (j₁... to j_M) is allocated, so will<maths id="math0018" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">i, j</mtext></mrow></msub><mtext> ≤ 0</mtext></mrow></math><img file="EP1453339A1_D0018.tif" /></maths> For<maths id="math0019" num=""><math display="block"><mrow><mtext mathvariant="italic">j</mtext><mtext> ∉ {</mtext><msub><mrow><mtext mathvariant="italic">j</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>, ..., </mtext><msub><mrow><mtext mathvariant="italic">j</mtext></mrow><mrow><mtext mathvariant="italic">M</mtext></mrow></msub><mtext>}</mtext></mrow></math><img file="EP1453339A1_D0019.tif" /></maths> committed. When searching for packet data channels for the new subscriber N + 1 becomes<maths id="math0020" num=""><math display="block"><mrow><msub><mrow><mtext mathvariant="italic">p</mtext></mrow><mrow><mtext mathvariant="italic">N</mtext></mrow></msub><msub><mrow><mtext>​</mtext></mrow><mrow><mtext>+1,</mtext></mrow></msub><msub><mrow><mtext>​</mtext></mrow><mrow><mtext mathvariant="italic">j</mtext></mrow></msub><mtext> ≤ 0</mtext></mrow></math><img file="EP1453339A1_D0020.tif" /></maths> for all<maths id="math0021" num=""><math display="block"><mrow><mtext mathvariant="italic">j</mtext><mtext> ∉ {</mtext><msub><mrow><mtext mathvariant="italic">j</mtext></mrow><mrow><mtext>1</mtext></mrow></msub><mtext>, ..., </mtext><msub><mrow><mtext mathvariant="italic">j</mtext></mrow><mrow><mtext mathvariant="italic">M</mtext></mrow></msub><mtext>}</mtext></mrow></math><img file="EP1453339A1_D0021.tif" /></maths> committed to prevent the subscriber N + 1 is allocated on another packet data channel.

Rational assignments are examined. As reasonable assignments, combinations of packet data channels are considered, the number of which corresponds to the time-slot capability of the mobile terminal and which are arranged on successive packet data channels. If the number k of the packet data channels 6 is the time slot capability of the mobile terminal 4, then only the three alternatives {0,1,2,3}, {1,2,3,4}, {2,3,4,5 }. For these three alternatives, the assignment is calculated. Subsequently, the largest is selected from the resulting values ​​V of the allocation matrix. In this approach, although an allocation, which would be associated with a greater redistribution of channels, and possibly represents the real optimum, can not be found. This will limit the number of linear optimizations that need to be calculated. This saves processor power.

As a result, the assignment matrix (p_ij), the number of assigned A_toChannels (A_j) and the selected modulation / coding scheme CS for the subscriber N + 1.

To prepare the optimization task, you must start from the number of available A_toChannels and the vector S^c the best available modulation / coding scheme CS is calculated. This is the modulation / coding scheme with the largest data rate, for which sufficient A_toChannels are already assigned to corresponding packet data channels or sufficient A_toChannels are freely available. For the given modulation / coding scheme, then the matrices and vectors are constructed, which are input variables for the linear optimization.

In this preparation, a decision is already made, which A_toChannels and which modulation / coding scheme is to be assigned. Using linear optimization, the optimal allocation (<i>p</i>_{<i>i, j</i>}) and their value V determined. As a result, among the preselected allocation options of A_toChannels and the modulation / coding scheme selected the most favorable.

In the method, the allocation of subscribers to their packet data channels is preserved. However, each participant's share of each channel may change with each allocation. This will preserve the quality of service requirements of already assigned users.

If a subscriber ends his connection, the resource allocations for the remaining users are recalculated. The method then causes the remaining users to continue to be assigned the same packet data channels. If packet data channels become empty as a result, a heuristic shift can be used to change part of the allocations.

If the radio conditions for already allocated users change significantly, the joint assignment should be recalculated. The same applies if A_toChannels become free.

In one embodiment, a base station transceiver unit is considered with 6 packet data channels {0,1,2,3,4,5}. At the beginning all packet data channels are empty. It is assumed that the maximum number of subscribers to which a packet data channel can be assigned is 8. Thus, the below limit for the shares (p_{i, j}) 1/8 if the subscriber i is allocated to the packet data channel j. It is assumed that 26 A_toChannels on the A_toInterface are available. None of the A_toChannels is allocated.

In the embodiment, the consecutive arrival of subscribers 1, 2 and 3 is considered. The properties of participants 1, 2 and 3 are shown in Table 1.<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="5" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="31.50mm" /><colspec colnum="2" colname="col2" colwidth="31.50mm" /><colspec colnum="3" colname="col3" colwidth="31.50mm" /><colspec colnum="4" colname="col4" colwidth="31.50mm" /><colspec colnum="5" colname="col5" colwidth="31.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="left"><b>Participant 1</b></entry><entry namest="col3" nameend="col3" align="left"><b>Participant 2</b></entry><entry namest="col4" nameend="col4" align="left"><b>Participant 3</b></entry><entry namest="col5" nameend="col5" rowsep="0" /></row><row><entry namest="col1" nameend="col1" align="left"><b>Signal transmission ratio C / I</b></entry><entry namest="col2" nameend="col2" align="left">15 dB</entry><entry namest="col3" nameend="col3" align="left">20 dB</entry><entry namest="col4" nameend="col4" align="left">30 dB</entry><entry namest="col5" nameend="col5" /></row><row><entry namest="col1" nameend="col1" align="left"><b>Data rate for the modulation / coding scheme</b></entry><entry namest="col2" nameend="col2" align="left">S^c</entry><entry namest="col3" nameend="col3" align="left">S^c</entry><entry namest="col4" nameend="col4" align="left">S^c</entry><entry namest="col5" nameend="col5" align="left"><b>#Abis TS via PDCH</b></entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">MCS-1</entry><entry namest="col2" nameend="col2" align="left">8.4Kbit / s</entry><entry namest="col3" nameend="col3" align="left">8.8Kbit / s</entry><entry namest="col4" nameend="col4" align="left">8.8Kbit / s</entry><entry namest="col5" nameend="col5" align="left">1</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-2</entry><entry namest="col2" nameend="col2" align="left">10.6</entry><entry namest="col3" nameend="col3" align="left">11.1</entry><entry namest="col4" nameend="col4" align="left">11.2</entry><entry namest="col5" nameend="col5" align="left">2</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-3</entry><entry namest="col2" nameend="col2" align="left">13.7</entry><entry namest="col3" nameend="col3" align="left">14.6</entry><entry namest="col4" nameend="col4" align="left">14.8</entry><entry namest="col5" nameend="col5" align="left">2</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-4</entry><entry namest="col2" nameend="col2" align="left">15.4</entry><entry namest="col3" nameend="col3" align="left">17.0</entry><entry namest="col4" nameend="col4" align="left">17.6</entry><entry namest="col5" nameend="col5" align="left">2</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-5</entry><entry namest="col2" nameend="col2" align="left">18.1</entry><entry namest="col3" nameend="col3" align="left">21.6</entry><entry namest="col4" nameend="col4" align="left">22.4</entry><entry namest="col5" nameend="col5" align="left">2</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-6</entry><entry namest="col2" nameend="col2" align="left">24.5</entry><entry namest="col3" nameend="col3" align="left">27.2</entry><entry namest="col4" nameend="col4" align="left">29.6</entry><entry namest="col5" nameend="col5" align="left">3</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-7</entry><entry namest="col2" nameend="col2" align="left">24.3</entry><entry namest="col3" nameend="col3" align="left">35.9</entry><entry namest="col4" nameend="col4" align="left">44.5</entry><entry namest="col5" nameend="col5" align="left">4</entry></row><row><entry namest="col1" nameend="col1" align="left">MCS-8</entry><entry namest="col2" nameend="col2" align="left">22.6</entry><entry namest="col3" nameend="col3" align="left">39.7</entry><entry namest="col4" nameend="col4" align="left">53.6</entry><entry namest="col5" nameend="col5" align="left">5</entry></row><row><entry namest="col1" nameend="col1" align="left">CS-9</entry><entry namest="col2" nameend="col2" align="left">19.2</entry><entry namest="col3" nameend="col3" align="left">38.2</entry><entry namest="col4" nameend="col4" align="left">57.6</entry><entry namest="col5" nameend="col5" align="left">5</entry></row><row><entry namest="col1" nameend="col1" align="left"><b>Mobile Time Slot Capability</b></entry><entry namest="col2" nameend="col2" align="left">4 time slots</entry><entry namest="col3" nameend="col3" align="left">3 time slots</entry><entry namest="col4" nameend="col4" align="left">4 time slots</entry><entry namest="col5" nameend="col5" /></row><row><entry namest="col1" nameend="col1" align="left"><b>Target data rate</b></entry><entry namest="col2" nameend="col2" align="left">64 Kbit / s</entry><entry namest="col3" nameend="col3" align="left">111 Kbit / s</entry><entry namest="col4" nameend="col4" align="left">80 Kbit / s</entry><entry namest="col5" nameend="col5" /></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left"><b>Minimum data rate</b></entry><entry namest="col2" nameend="col2" align="left">16 Kbit / s</entry><entry namest="col3" nameend="col3" align="left">32 Kbit / s</entry><entry namest="col4" nameend="col4" align="left">16 Kbit / s</entry><entry namest="col5" nameend="col5" /></row></tbody></tgroup></table></tables>

In the table, the signal-to-interference ratio, the data rates for a given modulation / coding scheme, the ability of the mobile terminal to transmit and receive simultaneously on different time slots, ie the mobile timeslot capability, the target data rate and the minimum data rate, are indicated respectively. For the different modulation / coding schemes, the number of A is additionally required_toChannels per packet data channel A_to TS specified by TDCH.

From this data is prepared the list<maths id="math0022" num=""><math display="block"><mrow><mtext>{</mtext><msup><mrow><mtext mathvariant="italic">S</mtext></mrow><mrow><mtext mathvariant="italic">c</mtext></mrow></msup><mtext> : </mtext><mtext mathvariant="italic">C</mtext><mtext> = </mtext><mtext mathvariant="italic">MCS</mtext><mtext> -1,... ,</mtext><mtext mathvariant="italic">MCS</mtext><mtext> - 9}</mtext></mrow></math><img file="EP1453339A1_D0022.tif" /></maths> indicating what data rates the subscriber is expected to have on each of the packet data channels if only the subscriber is allocated to these packet data channels.

Upon arrival of the subscriber 1, it is checked which possible resources are available (see FIG. 2, step 1). The best modulation and coding scheme for participant 1 is MCS-6. This allows subscriber 1 to reach up to 24.5 Kbps on each of the packet data channels. Subscriber number 1 is allocated to the packet data channels {0,1,2,3}. For each of the packet data channels will be 3 A_toChannels needed. For the assignment matrix P thus results<maths id="math0023" num=""><math display="block"><mrow><mtext mathvariant="italic">P</mtext><mtext> = [1.0 1.0 1.0 1.0 0.0 0.0].</mtext></mrow></math><img file="EP1453339A1_D0023.tif" /></maths>

For the A_toAllocation vector results<maths id="math0024" num=""><math display="block"><mrow><mtext>A = [3 3 3 3 0 0].</mtext></mrow></math><img file="EP1453339A1_D0024.tif" /></maths>

For the participant 1 are now 12 A._toChannels occupied. This leaves 26-12 = 14 A_to-Channels.

Subsequently, a connection for subscriber 2 is established. For subscriber 2, MSC-8 is the modulation / coding scheme where the highest data rate of 39.7 Kbps can be achieved on each packet data channel if subscriber 2 does not need to share the packet data channels with another user. The modulation / coding scheme MCS8 requires 5 A_toChannels for each packet data channel. For the participant 2, there are thus four alternatives of assignment. There are enough A_toChannels are available in order to be able to assign the best modulation / coding scheme to subscriber 2.

Alternative 1: Allocation of subscriber 2 to the packet data channels {0,1,2}. The result is the following assignment matrices P₁ and A_toVectors A₁ with the value V₁<maths id="math0025" num=""><img file="EP1453339A1_D0025.tif" /></maths>

For this allocation, for each of the packet data channels {0,1,2} 2 A_toChannels additionally required. This means that there remain free A's_toChannels: 14-6 = 8.

Alternative 2: Allocation of the subscriber 2 to the packet data channels {1,2,2,3}. This results<maths id="math0026" num=""><img file="EP1453339A1_D0026.tif" /></maths>

Also in this case, two additional A's must be provided for the packet data channels {1,2,3}_toChannels are used. This leaves 14-6 = 8 unused A_to-Channels.

Alternative 3: Allocation of subscriber 2 to the packet data channels {2,3,4}. This results<maths id="math0027" num=""><img file="EP1453339A1_D0027.tif" /></maths>

In this case, for the packet data channels {2,3} there must be 2 additional A's_toChannels are assigned, for packet data channel 4 5 additional A's must be assigned_toChannels. This results for the remaining A_toChannels 14-9 = 5.

Alternative 4: Allocation of the subscriber 2 to the packet data channels {3,4,5}. This results<maths id="math0028" num=""><img file="EP1453339A1_D0028.tif" /></maths>

In this case, on the packet data channel 3 two additional A_toChannels and on the packet data channels {4,5} 5 A each_toChannels. Therefore 14-12 = 2 free A remain_to-Channels.

For each of the alternatives, the value V becomes_i, i = 1,2,3,4 calculated using a linear optimization (see step 2 in Figure 2). It determines the maximum that is achieved with the alternative 4 (see step 3 in Figure 2). Therefore, the subscriber 2 is allocated the resources corresponding to the alternative 4 (see step 4 in Fig. 2).

Subsequently, another connection for subscriber 3 is established. The initial situation is that only two free A_toChannels are available. For subscriber 3, the best modulation / coding scheme would be MCS-9, which can achieve a maximum data rate of 57.6 Kbit / s. Because of the occupancy of the A_toChannels, the subscriber 3 can receive the modulation / coding scheme MCS-9 only on the packet data channels {2, 3, 4, 5}. When allocating on the packet data channels {1,2,3,4}, it is only possible to use the modulation / coding scheme MCS-7 or lower coding schemes, where 4 A_toChannels per packet data channel are required. When allocating to the packet data channels {0, 1, 2, 3}, only the modulation / coding scheme MCS-6 and lesser coding schemes are possible, since when using MCS-6, only 3 A_toChannels per packet data channel are required.

In the following, the assignment matrix P is determined for the allocation alternatives found_i, the A_toAllocation vector A_i and the value V_i determined.

Alternative 1: Allocation of subscriber 3 to the packet data channels {0,1,2,3} with the modulation / coding scheme MCS-6 leads to the following result<maths id="math0029" num=""><img file="EP1453339A1_D0029.tif" /></maths>

There is no additional A for this alternative_toChannels are assigned, two unused A remain_to-Channels.

Alternative 2: Allocation of the subscriber 3 to the packet data channels {1,2,3,4} with the modulation and coding scheme MCS-7 yields the following result<maths id="math0030" num=""><img file="EP1453339A1_D0030.tif" /></maths>

For this alternative, an additional A is added for the packet data channels 1 and 2_toChannel needed. This leaves no unused A_to-Channels.

Alternative 3: Allocation of the subscriber 3 to the packet data channels {2,3,4,5} with the modulation / coding scheme MCS-9. It turns out<maths id="math0031" num=""><img file="EP1453339A1_D0031.tif" /></maths>

For this alternative, the packet data channel 2 has two more A_toChannels. This leaves no unused A_to-Channels.

Subsequently, the maximum of the values ​​V_i, i = 1,2,3, determined. V3 is the largest value, so that an allocation of the resources for participants 3 according to the alternative 3 takes place.

When disconnecting the subscriber 1, the matrix p is recalculated. It now has only two lines, the first line corresponds to the subscriber 2 and the second line to the subscriber 3. It turns out<maths id="math0032" num=""><img file="EP1453339A1_D0032.tif" /></maths>

It will be 6 A_toChannels released. The packet data channels 0 and 1 are no longer used. A shift of the subscriber 2 to the packet data channels 0,1,2 would have to be done with a heuristic method outside the described method.