Methods of load balancing and controlling congestion in a combined frequency division and time division multiple access communication system using intelligent login procedures and mobile terminal move commands

• US 5,898,681 A
• Filed: 09/30/1996
• Issued: 04/27/1999
• Est. Priority Date: 09/30/1996
• Status: Expired due to Fees

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: Amsc Subsidiary Corp. (PetIQ, Inc.)
• Inventors: Dutta, Santanu
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US08/724,115
• Time in Patent Office: 939 Days
• Field of Search: 370/229, 370/230, 370/231, 370/235, 370/280, 370/319, 370/321, 370/329, 370/330, 370/331, 370/337, 370/347, 370/349
• US Class Current: 370/229
• CPC Class Codes: H04B 7/18539 Arrangements for managing radio, resources, i.e. for establishing or releasing a connection

Abstract

In a time-division multiple-access TDMA communication system communication between a hub and a substantial number of mobile terminals is conducted over a plurality of channel groups. Load balancing toward a substantially uniform distribution of traffic loads among the channel groups is implemented by sharing control of the number of mobile terminals logged into each channel group between the hub and the mobile terminals. At login time, each mobile terminal selects the optimum channel group based on a channel group congestion factor broadcast on the forward TDM channel of each respective channel group. In addition, the hub has the ability to move a desired number of the mobile terminals from one to another channel group, based on information communicated in a network management service packet. The mobile terminals initiate moves based on statistical selection of mobile terminals using the communicated information.

Claims

1. In a method of communicating between a central station and any mobile terminals of a plurality of mobile terminals, wherein communication occurs over a selected channel group of a plurality of channel groups, each such channel group having one TDM channel for forward channel transmissions directed from the central station toward any of the plurality of mobile terminals, and at least one return channel for TDMA return channel transmissions by any of the plurality of mobile terminals with a login request prior to login, and by logged in mobile terminals communicating with the central station, a method of balancing transmission loads among said channel groups comprising the steps of:

transmitting channel group load balancing information over the TDM channel of a first channel group of the plurality of channel groups for reception by a first category of mobile terminals of the plurality of mobile terminals which receive said channel group load balancing information by being tuned to the TDM channel of the first channel group in preparation for and prior to logging into said first channel group, and by a second category of mobile terminals of the plurality of mobile terminals which receive said channel load balancing information while being logged into said first channel group at the time of transmission of said channel group load balancing information;

interpreting said channel group load balancing information by one category of the first and second categories of mobile terminals receiving such channel group load balancing information;

based on an outcome of interpreting said channel group load balancing information, selecting a second channel group of the plurality of channel groups as a preferred channel group for use to effect load balancing the channel groups; and

logging at least one of the mobile terminals having interpreted such channel group load balancing information into the second channel group.

2. The method of communicating according to claim 1, wherein the step of transmitting comprises:

transmitting channel group load balancing information over the TDM channel of the first channel group comprises periodically transmitting network management data including a channel group congestion factor for interpretation by mobile terminals of the first category of mobile terminals; and

optionally transmitting, during periods of load imbalances among selected channel groups of the plurality of channel groups, a load balancing service packet containing a new TDM channel code, a mobile terminal selection randomizer code, and a randomizing interval code, said load balancing service packet to be interpreted by at least a subset of the second category of mobile terminals.

3. The method of communicating according to claim 2, wherein interpreting said channel group load balancing information comprises:

the first category of mobile terminals comparing the channel group congestion factor to a predetermined threshold value;

upon finding the channel group congestion factor of the first channel group to exceed the predetermined threshold value, said first category of mobile terminals tuning successively to TDM channels of other of the plurality of channel groups; and

logging into a second channel group of the plurality of channel groups when a second channel group congestion factor, transmitted over the respective TDM channel such second channel group, is less than the threshold value, and logging into a primary assigned channel group when the respective channel group congestion factors of all TDM channels successively tuned to exceed the threshold value.

4. The method of communicating according to claim 2, wherein interpreting said channel group load balancing information comprises mobile terminals, of said subset of the second category of mobile terminals to interpret the load balancing service packet, generating a random move number and comparing the generated random move number to the mobile terminal selection randomizer code, and upon and after such comparison indicates that any such random move number is move-determining, by exceeding the mobile terminal selection randomizer code, the respective second category mobile terminal having generated such move-determining random move number logging into a second channel group specified by the new login channel code of the load balancing service packet.

5. The method of communicating according to claim 2, comprising,

defining said subset of the second category of the mobile terminals to interpret the load balancing service packet by:

transmitting in such load balancing service packet a mobile terminal address field, such mobile terminal address field including a specific mobile terminal code, thereby defining a subset of one of the second category of the mobile terminals to interpret the load balancing service packet.

6. The method of communicating according to claim 2, comprising:

selecting the subset of the second category of the mobile terminals to include all of the second category mobile terminals.

7. The method of communicating according to claim 2, comprising:

selecting the subset of the second category of the mobile terminals to correspond to the mobile terminals of ail of the second category mobile terminals assigned to a designated customer.

8. The method of communicating according to claim 2, comprising:

transmitting information over any of the forward TDM channels of the plurality of channel groups formatted into frames of data fields of binary data, which data are transmitted at a predetermined data rate, the frames having a predetermined timed length corresponding to a timed frame period and containing a predetermined amount of data depending on the data rate; and

interpreting said channel group load balancing information by mobile terminals of said subset of the second category of mobile terminals to interpret the load balancing service packet includes generating a random move number and comparing the generated random move number to the mobile terminal selection randomizer code, and upon and after such comparison indicates that any such random move number is move-determining, by exceeding the mobile terminal selection randomizer code, the method further comprising,

the respective second category mobile terminal having generated such move-determining random move number generating a random move interval number, comparing the random move interval number to the randomizing interval code of the load balancing service packet to generate a random frame delay period, remaining in the first channel group for the length of the generated frame delay period, and then logging into the second channel group specified by the new TDM channel code.

9. The method of communicating according to claim 8, wherein generating a random frame delay period constitutes generating a random frame count starting with the frame in which the load balancing service packet is received to a maximum frame count specified by the randomizing interval code, subsequent to which such second category mobile terminal logs into the second channel group specified by the new login channel code.