EP0750440A2
Expired / Lapsed
EP
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Method and apparatus for call admission control in CDMA mobile communication system
Assignee: NTT Docomo Inc
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Filing: 1996-06-21
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Granted: —
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Expires: 2016-06-21
Abstract
Abstract A call admission control scheme for a CDMA mobile communication system which can satisfy a given connection quality (blocking probability) while guaranteeing a predetermined communication quality. At each base station, a blocking probability and an outage probability of communication quality at each base station are calculated to adjust a maximum number of simultaneously connectable users at each base station according to the calculated results, and a call admission control is carried out according to the adjusted maximum number of simultaneously connectable users. A maximum number of simultaneously connectable users or an interference threshold can be determined from a first relationship between an offered traffic and a maximum number of simultaneously connectable users or an interference threshold for guaranteeing the prescribed communication quality and a second relationship between an offered traffic and a maximum number of simultaneously connectable users or an interference threshold for satisfying the prescribed blocking probability, and used for the call admission control.
Inventors
- 👤 Yoshihiro Ishikawa
- 👤 Narumi Umeda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 19:49
CPC Classifications
H; H04; H04W; H04W72/00
Claims Analysis
Total Claims: 50
Claim 1
Independent Claim
125 words
A method of call admission control in a CDMA mobile communication system having a plurality of base stations and mobile stations, the method comprising the steps of: calculating at each base station a blocking probability and an outage probability of communication quality within a radio zone of each base station; adjusting at each base station a maximum number of simultaneously connectable users within a radio zone of each base station according to the blocking probability and the outage probability of communication quality calculated at the calculating step; and carrying out at each base station a call admission control for each new call occurred within a radio zone of each base station according to the maximum number of simultaneously connectable users adjusted at the adjusting step.
Claim 2
Dependent Claim
45 words
The method of claim 1, wherein the calculating step calculates the blocking probability according to a number of originated calls, a number of terminated calls, and a number of incomplete originated or terminated calls which are measured within a radio zone of each base station.
Claim 3
Dependent Claim
30 words
The method of claim 1, wherein the calculating step calculates the blocking probability according to a number of currently connected users measured within a radio zone of each base station.
Claim 4
Dependent Claim
33 words
The method of claim 1, wherein the calculating step calculates the outage probability of communication quality according to a signal to interference power ratio measured within a radio zone of each base station.
Claim 5
Dependent Claim
31 words
The method of claim 1, wherein the calculating step calculates the outage probability of communication quality according to an interference power level measured within a radio zone of each base station.
Claim 6
Dependent Claim
50 words
The method of claim 1, wherein the adjusting step decreases the maximum number of simultaneously connectable users within a radio zone of each base station when the outage probability of communication quality calculated at the calculating step is greater than a prescribed threshold for the outage probability of communication quality.
Claim 7
Dependent Claim
70 words
The method of claim 1, wherein the adjusting step increases the maximum number of simultaneously connectable users within a radio zone of each base station when the blocking probability calculated at the calculating step is greater than a prescribed threshold for the blocking probability and the outage probability of communication quality calculated at the calculating step is not greater than a prescribed threshold for the outage probability of communication quality.
Claim 8
Dependent Claim
140 words
The method of claim 1, wherein the adjusting step decreases the maximum number of simultaneously connectable users within a radio zone of each base station when the outage probability of communication quality calculated at the calculating step is greater than a prescribed first threshold for the outage probability of communication quality, and increases the maximum number of simultaneously connectable users within a radio zone of each base station when the blocking probability calculated at the calculating step is greater than a prescribed threshold for the blocking probability and the outage probability of communication quality calculated at the calculating step is not greater than a prescribed second threshold for the outage probability of communication quality, where the prescribed second threshold for the outage probability of communication quality is lower than the prescribed first threshold for the outage probability of communication quality.
Claim 9
Dependent Claim
51 words
The method of claim 1, wherein the calculating step calculates the blocking probability by counting a number of originated or terminated calls and a number of blocked calls, and setting the blocking probability equal to the counted number of blocked calls divided by the counted number of originated or terminated calls.
Claim 10
Dependent Claim
95 words
The method of claim 1, wherein the calculating step calculates the outage probability of communication quality by measuring a communication quality, judging whether the communication quality is degraded or not according to a prescribed threshold, counting a first number indicating a number of times for judging that a communication quality is degraded and a second number indicating a number of times for judging that a communication quality is not degraded, and setting the outage probability of communication quality equal to the first number divided by a sum of the first number and the second number,
Claim 11
Dependent Claim
48 words
The method of claim 1, wherein the carrying out step admits a connection of each new call when a number of currently connected users is less than the maximum number of simultaneously connectable users adjusted at the adjusting step, and rejects a connection of each new call otherwise.
Claim 12
Independent Claim
125 words
An apparatus for call admission control in a CDMA mobile communication system having a plurality of base stations and mobile stations, the apparatus comprising: first control means, provided at each base station, for calculating a blocking probability and an outage probability of communication quality within a radio zone of each base station, and adjusting a maximum number of simultaneously connectable users within a radio zone of each base station according to the calculated blocking probability and outage probability of communication quality; and second control means, provided at each base station, for carrying out a call admission control for each new call occurred within a radio zone of each base station according to the maximum number of simultaneously connectable users adjusted by the first control means.
Claim 13
Dependent Claim
46 words
The apparatus of claim 12, wherein the first control means calculates the blocking probability according to a number of originated calls, a number of terminated calls, and a number of incomplete originated or terminated calls which are measured within a radio zone of each base station.
Claim 14
Dependent Claim
31 words
The apparatus of claim 12, wherein the first control means calculates the blocking probability according to a number of currently connected users measured within a radio zone of each base station.
Claim 15
Dependent Claim
34 words
The apparatus of claim 12, wherein the first control means calculates the outage probability of communication quality according to a signal to interference power ratio measured within a radio zone of each base station.
Claim 16
Dependent Claim
32 words
The apparatus of claim 12, wherein the first control means calculates the outage probability of communication quality according to an interference power level measured within a radio zone of each base station.
Claim 17
Dependent Claim
47 words
The apparatus of claim 12, wherein the first control means decreases the maximum number of simultaneously connectable users within a radio zone of each base station when the calculated outage probability of communication quality is greater than a prescribed threshold for the outage probability of communication quality.
Claim 18
Dependent Claim
63 words
The apparatus of claim 12, wherein the first control means increases the maximum number of simultaneously connectable users within a radio zone of each base station when the calculated blocking probability is greater than a prescribed threshold for the blocking probability and the calculated outage probability of communication quality is not greater than a prescribed threshold for the outage probability of communication quality.
Claim 19
Dependent Claim
129 words
The apparatus of claim 12, wherein the first control means decreases the maximum number of simultaneously connectable users within a radio zone of each base station when the calculated outage probability of communication quality is greater than a prescribed first threshold for the outage probability of communication quality, and increases the maximum number of simultaneously connectable users within a radio zone of each base station when the calculated blocking probability is greater than a prescribed threshold for the blocking probability and the calculated outage probability of communication quality is not greater than a prescribed second threshold for the outage probability of communication quality, where the prescribed second threshold for the outage probability of communication quality is lower than the prescribed first threshold for the outage probability of communication quality.
Claim 20
Dependent Claim
52 words
The apparatus of claim 12, wherein the first control means calculates the blocking probability by counting a number of originated or terminated calls and a number of blocked calls, and setting the blocking probability equal to the counted number of blocked calls divided by the counted number of originated or terminated calls.
Claim 21
Dependent Claim
96 words
The apparatus of claim 12, wherein the first control means calculates the outage probability of communication quality by measuring a communication quality, judging whether the communication quality is degraded or not according to a prescribed threshold, counting a first number indicating a number of times for judging that a communication quality is degraded and a second number indicating a number of times for judging that a communication quality is not degraded, and setting the outage probability of communication quality equal to the first number divided by a sum of the first number and the second number,
Claim 22
Dependent Claim
49 words
The apparatus of claim 12, wherein the second control means admits a connection of each new call when a number of currently connected users is less than the maximum number of simultaneously connectable users adjusted by the first control means, and rejects a connection of each new call otherwise.
Claim 23
Independent Claim
150 words
A method of call admission control in a CDMA mobile communication system having a plurality of base stations and mobile stations, the method comprising the steps of: obtaining a maximum offered traffic for satisfying a prescribed blocking probability while guaranteeing a prescribed communication quality, from a first relationship between an offered traffic and a maximum number of simultaneously connectable users for guaranteeing the prescribed communication quality and a second relationship between an offered traffic and a maximum number of simultaneously connectable users for satisfying the prescribed blocking probability; determining a maximum number of simultaneously connectable users for satisfying the prescribed blocking probability with respect to a given offered traffic not greater than the maximum offered traffic obtained at the obtaining step, from the second relationship; and carrying out a call admission control for each new call according to the maximum number of simultaneously connectable users determined at the determining step.
Claim 24
Dependent Claim
23 words
The method of claim 23, wherein the obtaining step uses the first relationship derived by guaranteeing a prescribed outage probability of communication quality.
Claim 25
Dependent Claim
150 words
The method of claim 24, wherein an outage probability of communication quality P loss is given by: P loss = k=0̸ N kP k c max +1-k ∞ p int (m)dm k=0̸ N kP k where N is a maximum number of simultaneously connectable users, P k is a probability for k users to be in a speech state within a cell of each base station, c max is a limit value for judging degradation of communication quality from a total sum of an interference from other users in a speech state within a cell of each base station and an interference from other cells of other base stations, P int (m) is a probability density distribution of an interference from other cells of other base stations, and m is a converted number of users at each base station equivalent to an interference from other cells of other base stations.
Claim 26
Dependent Claim
22 words
The method of claim 23, wherein the obtaining step and the determining step use the second relationship derived from Erlang's B formula.
Claim 27
Dependent Claim
38 words
The method of claim 23, wherein the obtaining step obtains the maximum offered traffic as an offered traffic value corresponding to an intersection of a curve expressing the first relationship and a straight line expressing the second relationship.
Claim 28
Dependent Claim
40 words
The method of claim 23, wherein the determining step determines the maximum number of simultaneously connectable users as a maximum number of simultaneously connectable users value corresponding to the given offered traffic on a straight line expressing the second relationship.
Claim 29
Dependent Claim
48 words
The method of claim 23, wherein the carrying out step admits a connection of each new call when a number of currently connected users is less than the maximum number of simultaneously connectable users determined at the determining step, and rejects a connection of each new call otherwise.
Claim 30
Independent Claim
134 words
A method of call admission control in a CDMA mobile communication system having a plurality of base stations and mobile stations, the method comprising the steps of: obtaining a maximum offered traffic for satisfying a prescribed blocking probability while guaranteeing a prescribed communication quality, from a first relationship between an offered traffic and an interference threshold for guaranteeing the prescribed communication quality and a second relationship between an offered traffic and an interference threshold for satisfying the prescribed blocking probability; determining an interference threshold for satisfying the prescribed blocking probability with respect to a given offered traffic not greater than the maximum offered traffic obtained at the obtaining step, from the second relationship; and carrying out a call admission control for each new call according to the interference threshold determined at the determining step.
Claim 31
Dependent Claim
23 words
The method of claim 30, wherein the obtaining step uses the first relationship derived by guaranteeing a prescribed outage probability of communication quality.
Claim 32
Dependent Claim
141 words
The method of claim 31, wherein an outage probability of communication quality P loss is given by: P loss = k=0̸ ∞ kP k c max +1-k ∞ p int (m)dm k=0̸ ∞ kP k where P k is a probability for k users to be in a speech state within a cell of each base station, c max is a limit value for judging degradation of communication quality from a total sum of an interference from other users in a speech state within a cell of each base station and an interference from other cells of other base stations, P int (m) is a probability density distribution of an interference from other cells of other base stations, and m is a converted number of users at each base station equivalent to an interference from other cells of other base stations.
Claim 33
Dependent Claim
76 words
The method of claim 30, wherein the obtaining step and the determining step use the second relationship derived from a blocking probability P block given by: P block = r=0̸ ∞ (1 - p(r)) P r where p(r) is a probability for a call to be admitted when a number of simultaneously connected users is r, and P r is a probability for the number of simultaneously connected users to be r within each base station.
Claim 34
Dependent Claim
38 words
The method of claim 30, wherein the obtaining step obtains the maximum offered traffic as an offered traffic value corresponding to an intersection of a curve expressing the first relationship and a straight line expressing the second relationship.
Claim 35
Dependent Claim
32 words
The method of claim 30, wherein the determining step determines the interference threshold as an interference threshold value corresponding to the given offered traffic on a straight line expressing the second relationship.
Claim 36
Dependent Claim
42 words
The method of claim 30, wherein the carrying out step admits a connection of each new call when a measured interference level is less than the interference threshold determined at the determining step, and rejects a connection of each new call otherwise.
Claim 37
Independent Claim
161 words
An apparatus for call admission control in a CDMA mobile communication system having a plurality of base stations and mobile stations, the apparatus comprising: a memory for storing a maximum number of simultaneously connectable users, predetermined by obtaining a maximum offered traffic for satisfying a prescribed blocking probability while guaranteeing a prescribed communication quality, from a first relationship between an offered traffic and a maximum number of simultaneously connectable users for guaranteeing the prescribed communication quality and a second relationship between an offered traffic and a maximum number of simultaneously connectable users for satisfying the prescribed blocking probability, and determining a maximum number of simultaneously connectable users for satisfying the prescribed blocking probability with respect to a given offered traffic not greater than the obtained maximum offered traffic, from the second relationship; and call admission control means for carrying out a call admission control for each new call according to the maximum number of simultaneously connectable users stored in the memory.
Claim 38
Dependent Claim
32 words
The apparatus of claim 37, wherein the memory stores the maximum number of simultaneously connectable users determined by using the first relationship derived by guaranteeing a prescribed outage probability of communication quality.
Claim 39
Dependent Claim
150 words
The apparatus of claim 38, wherein an outage probability of communication quality P loss is given by: P loss = k=0̸ N kP k c max +1-k ∞ p int (m)dm k=0̸ N kP k where N is a maximum number of simultaneously connectable users, P k is a probability for k users to be in a speech state within a cell of each base station, c max is a limit value for judging degradation of communication quality from a total sum of an interference from other users in a speech state within a cell of each base station and an interference from other cells of other base stations, P int (m) is a probability density distribution of an interference from other cells of other base stations, and m is a converted number of users at each base station equivalent to an interference from other cells of other base stations.
Claim 40
Dependent Claim
27 words
The apparatus of claim 37, wherein the memory stores the maximum number of simultaneously connectable users determined by using the second relationship derived from Erlang's B formula.
Claim 41
Dependent Claim
47 words
The apparatus of claim 37, wherein the memory stores the maximum number of simultaneously connectable users determined from the maximum offered traffic obtained as an offered traffic value corresponding to an intersection of a curve expressing the first relationship and a straight line expressing the second relationship.
Claim 42
Dependent Claim
40 words
The apparatus of claim 37, wherein the memory stores the maximum number of simultaneously connectable users determined as a maximum number of simultaneously connectable users value corresponding to the given offered traffic on a straight line expressing the second relationship.
Claim 43
Dependent Claim
48 words
The apparatus of claim 37, wherein the call admission control means admits a connection of each new call when a number of currently connected users is less than the maximum number of simultaneously connectable users stored in the memory, and rejects a connection of each new call otherwise.
Claim 44
Independent Claim
141 words
An apparatus for call admission control in a CDMA mobile communication system having a plurality of base stations and mobile stations, the apparatus comprising: a memory for storing an interference threshold, predetermined by obtaining a maximum offered traffic for satisfying a prescribed blocking probability while guaranteeing a prescribed communication quality, from a first relationship between an offered traffic and an interference threshold for guaranteeing the prescribed communication quality and a second relationship between an offered traffic and an interference threshold for satisfying the prescribed blocking probability, and determining an interference threshold for satisfying the prescribed blocking probability with respect to a given offered traffic not greater than the obtained maximum offered traffic, from the second relationship; and call admission control means for carrying out a call admission control for each new call according to the interference threshold stored in the memory.
Claim 45
Dependent Claim
28 words
The apparatus of claim 44, wherein the memory stores the interference threshold determined by using the first relationship derived by guaranteeing a prescribed outage probability of communication quality.
Claim 46
Dependent Claim
141 words
The apparatus of claim 45, wherein an outage probability of communication quality P loss is given by: P loss = k=0̸ ∞ kP k c max +1-k ∞ p int (m)dm k=0̸ ∞ kP k where P k is a probability for k users to be in a speech state within a cell of each base station, c max is a limit value for judging degradation of communication quality from a total sum of an interference from other users in a speech state within a cell of each base station and an interference from other cells of other base stations, P int (m) is a probability density distribution of an interference from other cells of other base stations, and m is a converted number of users at each base station equivalent to an interference from other cells of other base stations.
Claim 47
Dependent Claim
77 words
The apparatus of claim 44, wherein the memory stores the interference threshold determined by using the second relationship derived from a blocking probability P block given by: P block = r=0̸ ∞ (1 - p(r)) P r where p(r) is a probability for a call to be admitted when a number of simultaneously connected users is r, and P r is a probability for the number of simultaneously connected users to be r within each base station.
Claim 48
Dependent Claim
44 words
The apparatus of claim 44, wherein the memory stores the interference threshold determined by using the maximum offered traffic obtained as an offered traffic value corresponding to an intersection of a curve expressing the first relationship and a straight line expressing the second relationship.
Claim 49
Dependent Claim
32 words
The apparatus of claim 44, wherein the memory stores the interference threshold determined as an interference threshold value corresponding to the given offered traffic on a straight line expressing the second relationship.
Claim 50
Dependent Claim
42 words
The apparatus of claim 44, wherein the call admission control means admits a connection of each new call when a measured interference level is less than the interference threshold stored in the memory, and rejects a connection of each new call otherwise.
References Cited (Backward Citations)
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