Browse Prior Art Database

Transfer of Encoded Voice as Connectionless Data over a Wireless Protocol Stack

IP.com Disclosure Number: IPCOM000010693D
Original Publication Date: 2003-Jan-08
Included in the Prior Art Database: 2003-Jan-08

Publishing Venue

Motorola

Related People

Ankush Chatterjee: AUTHOR [+3]

Abstract

Compliance with the BluetoothTM specification for voice communications imposes limitations on codec types, and the number of simultaneous voice users per access point. The SCO links inherently limit the number of simultaneous voice users on a single access point because of their circuit switched likeness. However, by employing asynchronous connectionless links (ACL) for voice transfer, any codec may be used, and the number of simultaneous users supported by an access point can be increased. These objectives can be accomplished while still remaining compliant to the specification generally, even though other non-specified codecs may be employed.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 20% of the total text.

Title: Transfer of Encoded Voice as Connectionless Data over a Wireless Protocol Stack

Authors: Ankush Chatterjee, Angel Favila and Shaowei Pan, Ph.D.

Abstract

Compliance with the BluetoothTM specification for voice communications imposes limitations on codec types, and the number of simultaneous voice users per access point. The SCO links inherently limit the number of simultaneous voice users on a single access point because of their circuit switched likeness. However, by employing asynchronous connectionless links (ACL) for voice transfer, any codec may be used, and the number of simultaneous users supported by an access point can be increased. These objectives can be accomplished while still remaining compliant to the specification generally, even though other non-specified codecs may be employed.

Introduction

Summary of the BluetoothTM Literature

The BluetoothTM specification incorporates support for audio generally, and for voice with respect to telephony applications.[1] The BluetoothTM Telephony Control protocol Specification, TCS-Binary, is a bit-oriented protocol that defines call control signaling for establishing speech and data calls between BluetoothTM capable devices.[2] According to the specification, multiple instances of TCS may exist simultaneously for purposes of handling multiple calls.[3] The internal structure of the TCS architecture contains the functional entities Call Control (CC), Group Management (GM), and ConnectionLess (CL).[4] The BluetoothTM specification defines TCS CL as a provision for exchanging signaling information that is not related to an ongoing call.[5] Further, signaling information can be exchanged without establishing a call. A message sent via TCS CL is defined as a CL INFO message.[6]

The BluetoothTM specification also defines baseband packet data unit (PDU) types, specifically “asynchronous connectionless” (ACL) data or “synchronous connection-oriented” (SCO) data.[7] The SCO links were designed for use as telephony quality voice links and are designated as 64Kbps channels per the BluetoothTM specification.[8] Codecs and data compression formats supported by the SCO are 64Kbps μ-law PCM format, 64Kbps A-law PCM format, and 64 Kbps CVSD (continuous variable slope delta) modulation format.[9] In accordance with the specification, an access point can support a maximum of three SCO channels at any given time, with a single SCO channel supporting a single user. The SCO channels provide circuit switched connectivity for telephony purposes. On the other hand, the ACL links were designed for sending data generally. The CL INFO message is defined for the purpose of sending and receiving non-voice data via an ACL link.

Summary of mobile station and network technology

A cellular mobile station, depending on the technology employed, may utilize any of a variety of voice codecs. For example, a CDMA mobile may employ an Enhanced Variable Rate Codec, EVRC. Likewise, a GSM mobile station may employ var...