Method of controlling the operation of a packet switched CDMA telecommunication network

• US 5,394,391 A
• Filed: 09/27/1993
• Issued: 02/28/1995
• Est. Priority Date: 04/05/1991
• Status: Expired due to Term

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Chen, Xiao H., Oksman, Juhani
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US08/119,225
• Time in Patent Office: 519 Days
• Field of Search: 370/18, 370/19, 370/21, 370/24, 370/60, 370/85.2, 370/85.3, 370/94.1, 375/1, 341/60, 371/32, 371/33
• US Class Current: 370/441
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]

Abstract

A method of controlling the operation of a packet switched CDMA telecommunication network, wherein N network users are connected to the network by respective terminals, and the terminal of each user is assigned an orthogonal receiver code. To improve the properties of the packet network, the network terminal wanting to transmit senses the channel forming the transmission path for the presence of the receiver code of the other communicating party, i.e. the receiving terminal, in signals transmitted by the other terminals, the receiving terminal being the terminal to which the sensing terminal wants to transmit data in packet format. If the receiver code is not detected in the channel, the terminal wanting to transmit initiates the transmission of packet-format data encoded by the receiver code, whereas if the receiver code is detected in the channel, the terminal wanting to transmit remains waiting so as to repeat the above-described sensing algorithm after a period of time.

Claims

1. A method of controlling the operation of a packet switched CDMA telecommunication network, wherein N network users (U_i,j) are connected to the network by a respective terminal (TER_i, TER_j, i, j=1→

N), and each terminal (TER_i) communicates by means of a transmitter (T_i, i=1→

N) and a receiver R_i, i=1→

N) with a receiver (R_j) and a transmitter (T_j) of another terminal (TER_j, j=1→

N) via a CDMA channel (1) forming the transmission path, and wherein a substantially orthogonal receiver code (r_i, r_j, i, j=1→

N) is assigned to the terminal (TER_i, TER_j) of each user, which code is used by the other terminals of the network for addressing and encoding packets to the particular terminal, comprising;

sensing by a network terminal (TER_i, i=1→

N) wanting to transmit the channel (1) forming the transmission path for the presence of the receiver code (r_j) of the receiving terminal (TER_j) of the other communicating party, in signals (S_i) transmitted by the other terminals, said receiving terminal (TER_j) being the terminal to which the sensing terminal (TER_i) wants to transmit data in packet format, and

if the receiver code (r_j) is not detected in the channel, initiating by said terminal (TER_i) wanting to transmit the transmission of packet-format data encoded by said receiver code (r_j) to the receiver (R_j) of the receiving terminal (TER_j), whereas

if the receiver code (r_j) is detected in the channel, remaining waiting of said terminal (TER_i) wanting to transmit so as to repeat the sensing step after a period of time.

2. A method according to claim 1, wherein:

said sensing of the channel (1) forming the transmission path for the presence of the receiver code (r_j) is carried out by;

applying a signal (S_i) derived from the channel (1) and containing receiver codes (r) occurring in signals transmitted by the other terminals, to a correlator (C_i) included in the receiver (R_i) of the sensing terminal, being the terminal (TER_i) wanting to transmit,

applying the identifying code (r_j) of the other communicating party, being the receiving terminal (TER_j) to the correlator (C_i) as a reference, and

then measuring in an output (C_i out) of the correlator (C_i) correlation between signal (S_i) and identifying code (Y_j) as applied to the correlator (C_i) in an output (C_i out) of the correlator (C_i).

3. A method according to claim 2, wherein:

if the level of auto-correlation, being correlation between the receiver codes (r_j) already present in the signal (S_i) derived from the channel, by being sensed from the channel (1), and the same receiver code (r_j) applied to the correlator as a reference, in the output (C_i out) of the correlator (C_i) exceeds a predetermined threshold value (K), the transmitter (T_i) of the sensing terminal, being the terminal (TER_i) wanting to transmit remaining waiting and not yet initiating the transmission of the packet to the receiver (R_j) of the receiving terminal (TER_j), whereas

if the level of auto-correlation is less than the predetermined threshold value (K), the sensing terminal, being the terminal (TER_i) immediately initiating the transmission of the packet.