Abstract:
A method for reducing overhead when transmitting and receiving an Internet Protocol (IP) packet by a device begins with receiving of the IP packet by the device. In the packet, an IP address of the packet has been removed and replaced with a watermarking signature based on the IP address. The IP address is obtained using the watermarking signature. The IP address is attached to the packet and the packet is forwarded by the device to a destination over a network using the IP address.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/114,286 filed Apr. 26, 2005, which claims the benefit of U.S. Provisional Application No. 60/658,090, filed Mar. 3, 2005, all of which are incorporated by reference as if fully set forth herein. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention generally relates to using watermarking to reduce communication overhead, and more particularly to using watermarking to reduce the overhead of Internet Protocol (IP) communications and to using radio frequency (RF) watermarking to replace some medium access control (MAC) functions and signalings. 
       BACKGROUND 
       [0003]    Wireless systems are susceptible in many respects. These susceptibilities are increasing as new wireless technologies are growing in prevalence. Ad-hoc networks, where individual users communicate with each other directly without using intermediary network nodes, create new susceptibilities to the users and the networks. These susceptibilities can be categorized as “trust”, “rights”, “identity”, “privacy”, and “security” related issues. 
         [0004]    “Trust” refers to the assurance that information communicated in these systems can be shared. To illustrate, a wireless user may want to know that a communication was sent to it from a trusted source and using trusted communication nodes. The user in an ad-hoc network may have no knowledge that the communication was transferred over a hacker&#39;s wireless device with packet sniffing software. Additionally, with the use of tunneling, intermediate nodes transferring the communication may be transparent to the wireless user. 
         [0005]    “Rights” (“rights management”) refers to the control of data. To illustrate, one wireless user may have limited rights in a wireless system. However, if that user colludes (knowingly or unknowingly) with a second node having superior rights, that user may gain rights above those that the user is allowed. 
         [0006]    “Identity” refers to the control linked to the identity of the wireless user. To illustrate, a rogue wireless device may attempt to access a wireless network by pretending to be an authorized user of the network, by using that authorized user&#39;s identity. 
         [0007]    “Privacy” refers to maintaining privacy of the individual, data and context. A wireless user may not want others to know which web sites he/she visits and, in particular, any information sent to these sites, such as financial information, medical information, etc. 
         [0008]    “Security” refers to the security of the data and context, such as preventing an unauthorized individual access to a wireless user&#39;s information. 
         [0009]    To reduce the susceptibility of wireless networks, techniques such as wired equivalent privacy (WEP), Wi-Fi protected access (WPA), extensible authentication protocol (EAP), IEEE 802.11i, and global system for mobile communications (GSM) based encryption are used. Although these techniques provide some protection, they are still susceptible to the trusts, rights, identity, privacy, and security issues discussed above. To illustrate, although a particular wireless communication node may have the correct WEP keys to communicate with a wireless user, that user may not know whether he/she can “trust” that node. 
         [0010]    Additionally, authentication of the user using these keys typically occurs at higher layers of the communication stack. Accordingly, even when these controls are in place, a rogue wireless user may have some (although limited) access to the communication stack. This access creates vulnerabilities, such as to denial of service attacks, among others. 
         [0011]    Steganography is the art of passing information in a manner that the very existence of the message is unknown. The goal of steganography is to avoid drawing suspicion to the transmission of a hidden message. If suspicion is raised, then this goal is defeated. Steganography encompasses methods of transmitting secret messages through innocuous cover carriers in such a manner that the very existence of the embedded messages is undetectable. Creative methods have been devised in the hiding process to reduce the visible detection of the embedded messages. 
         [0012]    Watermarking is a well-known technique for protecting and tracking digital information, which has been successfully exploited in the area of music and video data storage and communication. The traditional framework for watermarking consists of four elements: 1) a cover signal s, 2) a watermark w, 3) an embedding function E, and 4) a secret key k. The watermarked signal is then defined as s w =Ek{s,w}. The watermark carrying signal s w  must be robust to common signal processing operations, such as filtering, compression, etc., that are the basic functionalities of the network. Robustness is defined by the ability to extract the watermark from an altered signal. The second requirement of any watermarking scheme is imperceptibility; i.e., the difference between s and s w  must not alter the operation of the system in any perceptible manner. The watermark must also be transparent in the sense that the watermark-unaware portions of the network must be able to process s w  without additional hardware or software. The watermark must also be secure even though the watermarking algorithm itself may be public. This security is frequently achieved through a secret key that is exchanged with the receiver through some form of secure key exchange. 
         [0013]    The concept of digital watermarking is used in information assurance and user authentication. A watermark is embedded into the user data, which is then transported by the physical layer of the communication link. The recipient extracts the watermark and compares it with a local copy to authenticate the transmitter. 
         [0014]    Watermarks and signatures are techniques for adding metadata or unique information to media for signaling and/or security purposes. To reduce these susceptibilities to wireless communications, it is desirable to have alternate approaches to watermarking and adding signatures to wireless communications. 
         [0015]    The widespread dissemination of audio, video, images, and text data on wireless communication networks raises intellectual property and security issues. Digital watermarking technology has been recognized as a solution to address these issues in the wireless communication networks. Watermarking is typically only used for security and copyright protection purposes. Its other potential usages have not been fully explored. 
         [0016]    Internet Protocol (IP) V4 and IP V6 have been used for some applications in 3G (both universal mobile telecommunication system (UMTS) wideband code division multiple access (WCDMA) and Code Division Multiple Access (CDMA) 2000). It is also envisioned that the next generation wireless communication networks will be all IP-based, where the data will be transmitted using IP. However, the long IP header adds a large overhead for the data application even with a good IP header compression algorithm. 
         [0017]    In addition, some medium access control (MAC) functions and signaling can be replaced by using RF watermarking. In this way, the signaling load, overhead, and complexity in the system can be reduced. 
       SUMMARY 
       [0018]    The present invention exploits the application of watermarking in communication systems, leading to more efficient communications that are IP-based. In particular, the overhead of the IP header can be reduced by appropriately using watermarking. 
         [0019]    A method for reducing overhead when transmitting an Internet Protocol (IP) packet begins by selecting a watermarking signature based on the IP address of the packet. The watermarking signature is applied to the packet and the IP address is removed from the packet. The packet is sent to a receiver, which looks up the IP address of the packet by using the watermarking signature. The watermarking signature can be a radio frequency watermarking signature or a digital watermarking signature. 
         [0020]    A system for reducing overhead when transmitting an Internet Protocol (IP) packet includes a transmitter and a receiver. The transmitter includes an IP address to watermarking signature mapping book and an IP address to watermarking signature translator. The IP to watermarking signature translator examines the IP address of a packet, looks up the IP address in the IP to watermarking signature mapping book, removes the IP address from the packet, and applies the watermarking signature corresponding to the IP address to the packet. The packet is then transmitted to the receiver. The receiver includes a watermarking signature to IP address mapping book and a watermarking signature to IP address translator. The watermarking signature to IP translator examines the watermarking signature of a received packet, looks up the watermarking signature in the watermarking signature to IP mapping book to retrieve the IP address of the received packet, and adds the IP address to the received packet. The received packet is then forwarded to its destination. 
         [0021]    A method for using radio frequency (RF) watermarking to reduce medium access control (MAC) layer signaling in a wireless communication system begins by assigning a unique RF watermarking signature to each user. The RF watermarking signature is sent to a receiver during connection signaling. The RF watermarking signature is applied to subsequent transmissions to the receiver. The RF watermarking signature is examined at the receiver, whereby the watermarking signature is used to identify the user. 
         [0022]    A system for using radio frequency (RF) watermarking to reduce medium access control (MAC) layer signaling in a wireless communication system includes a transmitter, a receiver, and a network. The network includes a RF watermarking signature assignment device, which assigns a unique RF watermarking signature to the transmitter, including a user identifier. The transmitter includes a storage for storing the assigned RF watermarking signature, a connection signaling device for sending the assigned RF watermarking signature to the receiver, and a RF watermarking signature application device for applying the assigned RF watermarking signature to data to be transmitted. The receiver includes a RF watermarking signature extractor for removing the assigned RF watermarking signature from a received packet and decoding the assigned RF watermarking signature to determine the user identifier, whereby the user identifier in the MAC header can be replaced by the assigned watermarking signature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    A more detailed understanding of the invention may be had from the following description of a preferred embodiment, given by way of example, and to be understood in conjunction with the accompanying drawings, wherein: 
           [0024]      FIG. 1  is a flowchart of a method for using watermarking to reduce the overhead of an IP header; 
           [0025]      FIG. 2  is a diagram of a system implementing the method shown in  FIG. 1 ; 
           [0026]      FIG. 3  is a diagram of an implementation of the system shown in  FIG. 2  in a UMTS WCDMA system; 
           [0027]      FIG. 4  is a flowchart of a method for using radio frequency (RF) watermarking to replace a user identification field in a medium access control (MAC) header in an IP packet; 
           [0028]      FIG. 5  is a diagram of a system implementing the method shown in  FIG. 4 ; 
           [0029]      FIG. 6  is a flowchart of a method for using RF watermarking to replace a logical channel identification field in a MAC header in an IP packet; and 
           [0030]      FIG. 7  is a diagram of a system implementing the method shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    Hereafter, the term “station” (STA) includes, but is not limited to, a wireless transmit/receive unit, a user equipment, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, the term “access point” (AP) includes, but is not limited to, a base station, a Node B, a site controller, or any other type of interfacing device in a wireless environment. 
         [0032]    Reducing IP Header Overhead 
         [0033]    A method  100  for using watermarking to reduce the overhead of an IP header transmission over a wireless interface is shown in  FIG. 1 . The method  100  begins in a transmitter by taking a packet to be transmitted (step  102 ). The IP address is obtained from the packet (step  104 ) and is looked up in an IP address to watermark signature mapping book (step  106 ). The watermark signature mapped to the IP address is applied to the packet (step  108 ) and the packet is transmitted without an explicit IP address field (step  110 ). 
         [0034]    At a receiver, the method  100  continues by receiving the packet (step  112 ). The watermark signature is taken from the packet (step  114 ) and is looked up in a watermark signature to IP address mapping book (step  116 ). The IP address is added to the packet (step  118 ) and the packet is routed to the IP address (step  120 ). 
         [0035]      FIG. 2  shows a system  200  for implementing the method  100 , and includes a transmitter  202  and a receiver  204 . The transmitter  202  takes a data packet  210  that has an IP address and inputs the packet  210  into an IP address to watermarking signature translator  212 . The translator  212  looks up the IP address of the packet  210  in an IP address to watermarking signature mapping book  214 . The mapping book  214  contains a list that correlates an IP address to a particular watermarking signature. In a preferred embodiment, the mapping book  214  is stored in a database. The mapping of the IP address can, in some implementations, be quite trivial. For example, the IP address may be embedded exactly as it is, bit by bit. In an alternate embodiment, the watermark may code the entire IP header (which contains additional data), and not just the IP address. 
         [0036]    The translator  212  removes the IP address from the packet  210  and applies the watermarking signature from the mapping book  214 , creating a packet  216  which does not contain an IP address but instead contains the watermarking signature. The packet  216  is then sent to the receiver  204 . 
         [0037]    At the receiver  204 , a watermarking signature to IP address translator  220  receives the packet  216 . The translator  220  removes the watermarking signature from the packet  216  and looks up the watermarking signature in a watermarking signature to IP address mapping book  222 . Similar to the mapping book  214 , the mapping book  222  contains a list that correlates a watermarking signature to a particular IP address. The translator  220  adds the IP address to the packet  216  to create a data packet  224 , which contains the IP address. 
       Example 
       [0038]    An example system  300 , implemented in the uplink of a UMTS WCDMA system and using RF watermarking, is shown in  FIG. 3 . However, the invention applies to both the uplink and the downlink of wireless communication networks that use IP for some data applications (such as 3G) or use IP for all data applications (an all IP-based system). The present invention can also be used with wired communication systems using IP. 
         [0039]    The system  300  includes a transmitter  302 , a radio network controller (RNC) or Node B  304 , and a core network  306 . The transmitter  302  sends data packets  310  in the uplink for an IP-based application. The transmitter  302  inputs a packet  310  into an IP address to watermarking signature translator  312 . The translator  312  looks up the IP address of the packet  310  in an IP address to watermarking signature mapping book  314 . The mapping book  314  contains a pre-agreed list of IP addresses and their corresponding watermarking signatures. A watermarking device  316  takes the packet  310  and adds the watermarking signature corresponding to the IP address of the packet to create a packet  318  that does not have an IP address. 
         [0040]    The packet  318  is sent from the transmitter  302  to either the RNC or the Node B  304  that controls the transmitter  302 . The remainder of this discussion will refer to a RNC; however, the present invention operates in the same manner if a Node B were used. The packet  318  is received at the RNC  304  and is passed to a watermarking signature to IP address translator  320 . The translator  320  looks up the watermarking signature of the packet  318  in a watermarking signature to IP address mapping book  322 . The mapping book  322  contains a list of pre-agreed watermarking signatures and their corresponding IP addresses and contains the same information as the mapping book  314 . 
         [0041]    The translator  320  removes the watermarking signature from the packet  318 , and passes an IP address  324  and a packet  326  to an IP header device  328 . The IP header device  328  places the IP address  324  into a header and combines it with the packet  326  to create a packet  330  that contains an IP address. The packet  330  is then sent to the core network  306  and is routed to the appropriate IP address. The data packet will be routed to its destination according to its IP address (the same as current systems). In this way, the IP header overhead over the wireless interface is saved without degrading IP services. 
         [0042]    By using the system  300 , the RNC  304  can determine the IP address of a received data packet by mapping the received watermarking signature (in the packet  318 ) to the IP address according to the watermarking signature to IP address mapping book  322 . In this way, an IP header does not have to be transmitted over the wireless interface from the transmitter  302  to the RNC  304 . 
         [0043]    Replacing Fields in the MAC Header 
         [0044]    RF watermarking can also be used to replace some fields (such as user identification (ID), logical channel ID, etc.) in the medium access control (MAC) header in an IP packet. This can be done in wireless communication networks that use a shared channel and/or a dedicated channel. In networks that use a shared channel, the user ID is usually contained in the MAC header in order to allow the receiver to identify the associated user. In networks that use a shared channel or a dedicated channel, the logical channel ID is usually contained in the MAC header in order to allow the receiver to perform logical channel de-multiplexing for the user. 
         [0045]    Replacing the User ID Field 
         [0046]    A method  400  for using RF watermarking to replace the user ID field in the MAC header is shown in  FIG. 4 . The method  400  begins with a network assigning a unique RF watermarking signature to each user (step  402 ). The assigned RF watermarking signature is stored at the user&#39;s transmitter (step  404 ). The transmitter establishes a communication session with a receiver (step  406 ). The transmitter sends the user&#39;s RF watermarking signature to the receiver during establishment of the communication session, as part of the connection signaling information (step  408 ). The receiver stores the user&#39;s RF watermarking signature for later use (step  410 ). 
         [0047]    The transmitter sends regular communications to the receiver, and each communication contains the user&#39;s RF watermarking signature (step  412 ). The receiver receives the communications from the transmitter (step  414 ) and extracts the RF watermarking signature (step  416 ). The receiver uses the RF watermarking signature to identify the user (step  418 ). By using the RF watermarking, the user ID field can be eliminated from the MAC header and the receiver can still identify the associated user. The receiver knows which user the received signal belongs to by checking the RF watermarking signature. Therefore, there is no need for the transmitter to send a data packet with an explicit user ID field in the MAC header. 
         [0048]      FIG. 5  shows a system  500  for implementing the method  400 . The system  500  includes a network  502 , a transmitter  504 , and a receiver  506 . The network  502  includes a RF watermarking signature assignment device  510 , which assigns a RF watermarking signature to each user. 
         [0049]    The transmitter  504  includes a RF watermarking signature storage  520  which receives and stores the RF watermarking signature from the assignment device  510 . A connection signaling device  522  accesses the signature storage  520  to retrieve the RF watermarking signature assigned to the user. The connection signaling device  522  sends the RF watermarking signature to the receiver  506  via a transmitter  524 . Data  526  is provided to a RF watermarking signature application device  528  which applies the watermarking signature to the data, which is then forwarded to the transmitter  524  for transmission to the receiver  506 . 
         [0050]    The receiver  506  includes a receiver  530 , which receives communications from the transmitter  504 . Received communications are passed to a RF watermarking signature extractor  532 , which removes the watermarking signature from the received communications. The RF watermarking signature extractor  532  outputs data  534  and the user ID  536  associated with the transmitter  504 . 
         [0051]    Replacing the Logical Channel ID Field 
         [0052]    By using RF watermarking, the logical channel ID field can be eliminated from the MAC header and the receiver can still identify the associated logical channel and perform functions such as de-multiplexing. A method  600  for replacing the logical channel ID field in the MAC header with a RF watermarking signature is shown in  FIG. 6 . The method  600  begins with a network assigning an ID to each user (step  602 ) and assigning a logical channel to each user (step  604 ). The RF watermarking signature is created for each user by combining the assigned ID and the assigned logical channel (step  606 ). The watermarking signature of a user consists of two parts: the first part is unique for each user (the user ID), and the second part maps to an index  1 ,  2 , . . . , N, where N is the number of logical channels. 
         [0053]    The network sends the properly assigned RF watermarking signature to the transmitter, which receives and stores watermarking signature (step  608 ). The transmitter establishes a communication session with a receiver (step  610 ) and sends the watermarking signature as part of the connection signaling information (step  612 ). The receiver stores the user&#39;s watermarking signature for later use (step  614 ). 
         [0054]    The transmitter sends regular communications to the receiver, and each communication contains the user&#39;s RF watermarking signature (step  616 ). The receiver receives the communications from the transmitter (step  618 ) and extracts the watermarking signature (step  620 ). The receiver decodes the watermarking signature to identify the user and the logical channel used (step  622 ). 
         [0055]    The receiver can learn which user the received signal belongs to by checking the first part of the received RF watermarking signature. The receiver also can identify the associated logical channel by checking the second part of the watermarking signature. Therefore, there is no need for the transmitter to send a data packet with explicit user ID and logical channel fields in the MAC header. 
         [0056]    It is noted that the logical channel ID field is described as an exemplary case. The same approach can be applied for other fields in the MAC header that are used to distinguish data that belongs to the same user, such as priority class, queue ID, etc. 
         [0057]      FIG. 7  shows a system  700  for implementing the method  600 . The system  700  includes a network  702 , a transmitter  704 , and a receiver  706 . The network  702  includes a user ID assignment device  710 , which assigns an ID to each user. A logical channel assignment device  712  assigns a logical channel to each user. A RF watermarking signature creator  714  receives the user ID and the logical channel assignment and creates a RF watermarking signature for the user, which is then sent to the transmitter  704 . 
         [0058]    The transmitter  704  includes a RF watermarking signature storage  720  which receives and stores the watermarking signature from the signature creator  714 . A connection signaling device  722  accesses the signature storage  720  to retrieve the watermarking signature assigned to the user. The connection signaling device  722  sends the watermarking signature to the receiver  706  via a transmitter  724 . Data  726  is provided to a RF watermarking signature application device  728  which applies the watermarking signature to the data, which is then forwarded to the transmitter  724  for transmission to the receiver  706 . 
         [0059]    The receiver  706  includes a receiver  730 , which receives communications from the transmitter  704 . Received communications are passed to a RF watermarking signature extractor  732 , which removes the watermarking signature from the received communications. The signature extractor  732  outputs data  734 , the user ID  736 , and the logical channel  738  associated with the transmitter  704 . 
         [0060]    The components of the receiver, transmitter, or network can be implemented using an integrated circuit (IC), such as an application specific integrated circuit (ASIC), logical programmable gate array (LPGA), multiple ICs, LPGAs, discrete components, or a combination of IC(s), LPGA(s), and/or discrete component(s). 
         [0061]    The principles of the present invention are equally applicable to any type of wireless communication system. In addition, the principles of the present invention can be applied to wired communication systems by using digital watermarks, instead of RF watermarks. Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone (without the other features and elements of the preferred embodiments) or in various combinations with or without other features and elements of the present invention.