Method and apparatus for enhanced functions using a reserved field

• US 6,081,514 A
• Filed: 01/21/1998
• Issued: 06/27/2000
• Est. Priority Date: 10/18/1995
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Raith, Alex Krister
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Sam, Phirin
• Application Number:
  US09/009,723
• Time in Patent Office: 888 Days
• Field of Search: 370/321, 370/322, 370/324, 370/326, 370/328, 370/329, 370/336, 370/337, 370/347, 370/442, 370/503, 370/509, 370/510, 370/512, 370/320, 370/341, 370/342, 370/345, 370/348 , 370/349, 370/350, 370/441, 455/422, 455/434, 455/450, 455/515, 455/517, 455/95
• US Class Current: 370/321
• CPC Class Codes: H04B 7/2653 for logical channel control
• CPC Class Codes: H04J 3/07 using pulse stuffing for systems with different or fluctuating information rates or bit rates
• CPC Class Codes: H04J 3/125 One of the channel pulses or the synchronisation pulse is also used for transmitting monitoring or supervisory signals
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/003 Adaptive formatting arrangements particular to signalling, e.g. variable amount of bits
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04W 48/12 using downlink control channel

Abstract

A method and device are described for determining whether or not reserved bits of a field are assigned a function so that the mobile station may easily be adapted to perform enhanced functions. Such a determination enables first generation mobile stations to perform enhanced functions using bits which are initially reserved but may be assigned to service or function in later generations of the protocols. An indication of whether or not the reserved bits have been assigned a function may be sent on a broadcast channel by a usage information element. If the usage information element indicates that the reserved bits have not been assigned any service, such as power control, time alignment or short message services, the reserved bits may be used to enhance functions, such as equalization and synchronization. The method and device may further provide for improved decoding of the coded superframe phase/packet channel feedback (CSFP/PCF) field. Because the superframe phase (SFP) information is known when looking at the remaining bits from the start and end of the broadcast information, the number of possible codewords in the CSFP/PCF field may be reduced in the decoding process. Also, the length of a codeword to be decoded may be reduced based on a usage information element sent on the broadcast channel which indicates whether a reserved bit in the CSFP/PCF field is still reserved. More generally, the block code of any channel coded word, not necessarily packet data, may be effectively reduced based on knowledge of some information in the coded word. Decoding performance is improved by shortening the length of the codewords to be decoded because the shorter codewords are less susceptible to bit errors.

Claims

1. A method for analyzing reserved bits in a field of a wireless communication system, comprising the steps of:

(a) determining the state of a usage information element in a broadcast channel; and

(b) performing functions using the reserved bits in response to the state of said usage information element determined at said step (a).

2. A method according to claim 1, wherein said functions are performed by a mobile station with the reserved bits when said usage information element indicates that the reserve bits are not used for performing any other functions.

3. A method according to claim 1, wherein the functions include synchronization and equalization functions.

4. A device for analyzing reserved bits in a field of a wireless communication system, comprising the steps of:

a detector for determining the state of usage information element in a broadcast channel; and

a processor performing functions using the reserved bits in response to the state of said usage information element determined by said detector.

5. A device according to claim 4, wherein said functions are performed by a mobile station with the reserved bits when said usage information element indicates that the reserved bits are not used for performing any other functions.

6. A device according to claim 4, wherein the functions include synchronization and equalization functions.

7. A method for synchronizing to a received time slot comprising the steps of:

receiving a first time slot and a second time slot;

using a reserved field in said first time slot together with a synchronization field in said second time slot to synchronize to said second time slot.

8. The method of claim 7, further comprising the step of:

broadcasting an indication regarding whether said reserved field can be used for synchronization.