SE515509C2 - Adaptive air interface - Google Patents

Abstract

The invention relates to an adaptive air interface suitable for use in a cellular telecommunication system. The air interface contains various kinds of information elements having operating parameters such as framing data, synchronization data, information data and error control data. The adaptive air interface in accordance with the invention includes means for collecting parameter requirements, means for relating the parameter requirements to an input space, means for transforming the input space to an output space, the output space defining the operating parameters of the air interface. Preferably, the transformation means includes a fuzzy logic controller.

Description

25 30 35 40 515 509 ~~~~ ~ 2 fi g. 4A to F are diagrams of rank functions for output variables.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The Lu interface of the present invention is described below with reference to a mobile telecommunication system, but can be similarly applied to other air interfaces in a manner obvious to a person skilled in the art. The adaptive air interface contains a number of parameters and systems which are controlled in an adaptive manner. Some of the characteristics of the adaptive air interface are 0 TDMA or FH-TDMA (Frequency Hopping Time Division Multiple Access) 0 Frame period 0.5-2 ms base, x (1/8, 1/4, 1/2 , 2, 4) determined in an adaptive way 0 Fast power control at each burst 0 The mobile station (MS) provides return channel response at each burst 0 Network data rate: 32, 64, 128, 144, 192, 384 kb / s 0 Modulation system 2-16 PSK , QPSK, 8PSK / 2AM, 16QAM, 64QAM 0 FEC and / or turbo coding 0 Program-controlled parameters, partly by statistical logic 0 Supported modulation bandwidth 25, 50, 100 and 200 kHz 0 Frequency hopping function to improve fading resistance and to improve C / I performance 0 Supports 64 kb / s PCM and G722 high quality speech encoder at 20-7000 Hz, and primary speed 2B + D 0 Adapted to 2-20 ms total requirement for process delay Users are classified into 3 different categories 1. slow (stationary or walking) speed 2. between (fast walking, slow car) hasti ghet 3. high (fast car) speed The Lu interface according to the invention enables adaptivity to prevailing situations and scenarios. Namely, a number of possibilities arise with the following adaptive parameters in what is called the output space. 0 Frame time 0 Data speed 0 Bandwidth 0 Code speed 0 Intermittent factor 0 Mobile station (MS) power 515 509 §¿1j = §: j§-¿= .¿ _, = -1 - 3 0 Base station (BS) power The decision behind the parameters is based on measurements , user needs, consideration towards the operator and given resources using an optimization algorithm. These parameter requirements are retrieved by the interface. The requirements are related to the input data or the input space which contains the following parameters 0 Mobile speed 0 Delay 0 Distance 10 0 Delay variations 0 Capacity remaining in the mobile station 0 BER (Bit Error Rate) A number of examples are given and a device based on either a state machine or a solution with statistical logic is given to calculate the parameters under varied conditions.

I fi g. 1 shows a block diagram of the transformation of the entrance space into the exit space. The input space is processed by means of a logic control box which includes rules for the transformation. One way to carry out the transformation is by means of a state machine.

A state machine has a finite number of states of the input variables which are transformed by logic rules into output variables. Below is an example of logical rules in a state-of-the-art state-of-the-art machine.

ABOUT 25 {Mobile speed = Stationary AND Delay <6 ms AND Distance <8 km 30 AND Delay variations <1 us AND Remaining capacity> 0.4 AND 35 BER <l0-6-6} THEN {Frame time = 2ms AND 40 Data speed = 144 kbps. i ~. - r 10 15 20 25 30 35 40. | -. n u 515 509. . - = - »n AND Bandwidth = 100 kHz AND Code speed = 0.8 AND Intermittent factor = 45% AND BS power = 22 dBm AND MS power = 6 dBm} Another way is to perform the transformation using a statistical logic controller. In contrast to the state machine, the control unit uses statistical logic with a number of rank functions u. For each variable, a number of rank functions are defined. The rank functions can assume different values ranging from zero to one and not just the discrete numbers zero and one.

I fi g. 3A to F illustrate a number of rank functions for input variables. As can be seen in the figures, each invariant has a set of three rank functions that assume different values for a specific value on the x-axis. The control unit with statistical logic contains rules for transforming the input rank functions into output rank functions. An example of output rank functions is illustrated in Figs. 4A to F.

For each output variable, a separate value is thus obtained for three output variable ranking functions. The control unit with statistical logic also includes rules for "sharpening" (defuzzi fi cation), which gives a sharp value on the x-axis for the set of ranking function values.

Since the output values to be used in the air interface can only assume fixed values, an additional quantization operation takes place to obtain the sharp output variables. The sharpening operation and the quantization operation are illustrated in fi g. 2.

The logical rules for the control unit with the statistical logic, also called the statistical rule base, are determined by a detailed examination of the specific problems that exist. There are commercially available computer-aided procedures for denying, adjusting, and optimizing the statistical rule base.

An example of rules for statistical logic is given below.

IF {Mobile speed = low AND Delay = Medium AND 10 15 20 25 30 35,. «. : v 515 509 Distance = Medium Delay Variation = Small AND Remaining Capacity = Medium AND BER = Small} THEN {Frame Time = Low AND Data Speed = High AND Bandwidth = Low AND Code Speed = High AND Intermittent = Low AND BS Power = Medium AND MS effect = Medium The quantization operation is performed according to the example below: Let x be quantized according to x = {x1, x2, ..... xn}. Input xc gives xi, where xi As an example, the output variables can assume the following values: 0 Frame time = {0.5, 1, 2, 4, 8} ms 0 Data rate = {16, 32, 64, 128, 144, 192, 388 } kb / s 0 Bandwidth = {25, 50, 100, 200} kHz 0 Encoded = {4/5, 3/4, 2/3, 1/2) 0 Modulation system = {QPSK, SPSK, 16QAM, 8CPM / TCM , 640QAM, 32QAM / TCM, ...} 0 Function mode = {Normal, FH} 0 BS power = {30, 28, 26, ...} dBm Optimization of output variables, according to selected cost functions, is performed to t. ex. maximize quantities such as capacity and throughput, minimize power from the base station and the mobile station. The optimization is performed on the following variables: 515 509 6 0 Energy consumption 0 Spectrum use 0 Data rate 5 0 Quality measured in BER (bit error rate) The cost function CF is based on the following rule _ performance> <quality CF costs performance = data rate 10 kVÅlltClI I -10> <where the cost is expressed as an inversion of the spectrum use x energy consumption, ie 1 spectrum use> <energy consumption cost oc

Claims (8)

10 15 20 25 30 '515 509 7 PATENT REQUIREMENTS An adaptive air interface in a telecommunication system, comprising means for obtaining parameter requirements; means for relating the parameter requirements to an input space, i.e. given characteristics of the telecommunication system; means for transforming the input space into an output space, the output space defining the adapted operating parameters of the air interface, characterized in that the means for transforming comprise a control unit with statistical logic defining rank functions (p) of the input space and output space and rules for statistical logic the transformation between the entrance and exit spaces. Adaptive air interface according to Claim 1, characterized in that the rules of the statistical logic which determine the transformation between the entrance and exit spaces take place after a further sharpening operation. Adaptive air interface according to claim 1 or 2, characterized in that the means for retrieval have the ability to obtain information about measured values, user needs, consideration towards the operator and given resources. Adaptive air interface according to claim 1, 2 or 3, characterized in that the means for transformation comprise a state machine. Adaptive air interface according to claim 4, characterized in that the control unit for statistical logic can carry out optimization of the ranking functions, where the optimization is based on a cost function (CF). Adaptive air interface according to claim 5, characterized in that the cost function is based on the rule performance> <quality h = -ï-ii: oc costs 1 spectrum use> <energy consumption cost OC Adaptive air interface according to one of the preceding claims, characterized in that the input space comprises the parameters: data rate, mobile speed, delay, distance from the base station, delay variations, remaining capacity in the base station, and bit error rate (BER). Adaptive air interface according to claim 7, characterized in that the output space comprises the parameters: frame time, modulation system, bandwidth, code speed, intermittent factor, the power of the base station and the power of the mobile station.