HK1112355A - Method and apparatus for enhancing security of wireless communications - Google Patents

Description

Method and apparatus for increasing security of wireless communication

Technical Field

The invention relates to a method and a device for increasing communication security.

Background

Wireless communication systems are inherently vulnerable to many security and privacy related attacks. The continued growth in the popularity of these wireless systems has further increased these vulnerabilities. For example, even ad-hoc networks where individual users communicate directly with each other without using intermediate network nodes are vulnerable to security, privacy, identity, etc.

To reduce the inherent weaknesses of wireless networks, technologies including 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 have been applied to wireless communication systems. Although these techniques provide some protection, wireless communication systems are still vulnerable to attack. For example, assume that a wireless subscriber employs wired equivalent privacy security as a method for securing its wireless communication. Assume further that a user receives a communication from an unknown network node with the correct wired equivalent privacy key. In a communication containing the correct wired equivalent privacy key, the user should be alerted that the communication is from a trusted source. However, because the user is not familiar with the sending node, and because the wired equivalent privacy key may be hacked and copied as with other wireless communications, the user may not be willing to "trust" the communication. Moreover, even if a rogue user or hacker does not have the correct cable equivalent security keys, because authentication of these keys typically occurs at higher layers of the communication layer, the hacker can access the communication layer and, for example, perform a denial of service attack prior to authentication.

One technique for validating and preserving media content is known as watermarking. Watermarking, also referred to as "content watermarking", is a technique for adding hidden authentication and/or security data to a variety of media content. Digital watermarking extends this concept to digital media. However, content watermarking techniques are designed to protect content that is fairly static or unchanging. Thus, conventional content watermarking may not be a suitable protection method for securing dynamic content, such as wireless communications transmitted in a dynamic wireless environment.

It is desirable, therefore, to provide a method and apparatus for securing an enhanced watermarking scheme for wireless communications in a dynamic wireless environment.

Disclosure of Invention

The invention relates to a method and a device for increasing the security of wireless communication. The device comprises a security processing unit, a data processing unit, a cross-layer watermarking unit and an optional intelligent antenna processor. The security processing unit generates a token/key for watermarking and transmits a node security specification to other components. The data processing unit generates user data. The cross-layer watermarking unit preferably includes at least one of layer 2/3 (e.g., a higher layer watermarking layer), layer 1 (e.g., a Physical (PHY) watermarking layer), and layer 0 (e.g., a Radio Frequency (RF) layer). Each layer performs a different watermarking mechanism or degree. The cross-layer watermarking unit selectively embeds the token/key into the user data transmission at least one of the layers according to a security specification.

Drawings

A more particular understanding of the present invention may be had by reference to the following description of the preferred embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram of a communication system whose communication is secured with watermarking in accordance with the present invention;

FIG. 2 is a block diagram of a transmitter for transmitting a watermark in accordance with the present invention;

FIG. 3 is a block diagram of a method for securing a wireless communication device using cross-layer watermarking in accordance with the present invention;

FIG. 4 is a block diagram of a device implementing physical and radio watermarking schemes in accordance with the present invention; and

fig. 5 is a block diagram of a Radio Interface (RI) independent watermarking unit according to the present invention.

Detailed Description

The present invention relates to a watermarking scheme for embedding watermarks in content (e.g., user data), transmission, and/or communication devices in a secure and robust manner that provides for communication with tokens/keys (e.g., watermarks). A technique known as Dirty Paper Coding (DPC) is also provided to achieve the theoretical capacity of watermarking schemes.

The communication device includes, but is not limited to, a wireless transmit/receive unit (WTRU), a base station, or a wired communication device. The term "wtru" includes, but is not limited to, a User Equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. The term "base station" includes, but is not limited to, a mobile station, an address controller, a wireless network base station, or any other type of interfacing device in a wireless environment.

The features of the present invention may be integrated within an Integrated Circuit (IC) or may be configured in a circuit comprising a multitude of interconnecting components.

Dirty paper coding is a well-known best performing technique for wireless multiple-input multiple-output (MIMO) broadcast channels. In addition to its superior performance, dirty paper coding provides additional benefits as a transmission-side technique, meaning that the complexity of implementing this technique is shifted to the transmitter, not the receiver. As a result, a respective receiver is only required to recognize the details of the intended communication, which further eases the distribution of system information. Also, because each receiver may operate optimally without having to take care of the details of the intended transmissions to others, a dirty paper coding type system provides a way to hide transmissions from unintended receivers, thus making it suitable for supporting data hiding and watermarking and other security applications.

Although the analysis of dirty-paper coding has recently been significantly advanced in the understanding of the theory of this technology, little has been understood about how to build a practical communication system with dirty-paper coding. As discussed further below, the present invention describes a method and apparatus for configuring a communication system architecture to implement dirty paper coding.

In the present invention, watermarking is used to protect and enhance wireless communications. The term "transport watermarking" is used when watermarking is considered during transport and will be used interchangeably with the terms "security enhancement watermarking" and "cross-layer watermarking".

Fig. 1 is a block diagram of a communication system 100 in which a communication is secured with watermarking in accordance with one embodiment of the present invention. The data or information is generated by an information/data generator and is first secured by a "content watermark". The content watermarked data/information may be further secured by a "security enhanced watermark" in the communication device 104. To increase the security/robustness level of watermarking, "security enhancing watermarking" is performed at various protocol layers in the communication device. The watermarked user data is transmitted over a communication channel 106. The watermark is recovered by the communication device 108 and the original information/data is recovered by the receiver 110.

Content watermarking is an information embedding or hiding technique that is used to protect and/or control the multimedia content itself (including still images, pictures, sounds, moving images, and text) mostly by embedded information (e.g., watermarking information). As seen in fig. 1, a watermark message (or token/key) is directly embedded in content (e.g., multimedia content) to be protected, and thus can maintain its original form in the content. Applications include copyright protection, copy control, tamper detection, and data authentication, so content watermarking can be used for data integrity/authentication to determine if the data has been modified, and to determine who created the file at what time. Note that content watermarking is typically implemented at the application level.

On the other hand, security enhanced watermarking is another method of protecting and enhancing communications (especially wireless communications), where watermarking is considered at the transport level. In this example, the watermark message (or token/key) is embedded in the user data and/or the wireless air interface (e.g., a communication device or a wireless modem). Depending on where the watermark is embedded, a variety of embedding techniques are available. These techniques may be categorized as layers 2/3 (e.g., a higher layer watermarking layer), layer 1 (e.g., a Physical (PHY) watermarking layer), and layer 0 (e.g., a Radio Frequency (RF) layer).

Prior art watermarking is related to application and content (e.g., application level) watermarking. The present invention takes the concept of content watermarking and extends it to the transport level to address problems that content watermarking does not address solutions (e.g., link authentication). Content watermarking and delivery watermarking are performed in different steps: content watermarking is at the application level and watermarking is delivered at the transport level (including layer 2/3, the physical layer, and the radio frequency layer).

In delivering the watermark, the watermark itself may be, for example, a generator-specific signature (e.g., biometric signature) and/or a radio modem-specific signature (e.g., ESN and hardware non-linearity of the mobile phone). These signatures may be used to authenticate user data and/or devices. The watermark may be any other low data rate stream, which is considered side information.

Fig. 2 is a block diagram of a transmitter 200 for delivering a watermark in accordance with the present invention. Transmitter 200 includes a content watermarking unit 202, a Higher Level Processing (HLP) unit 204, a transport watermarking unit 206, and an adaptive cross-layer watermark spreader 214. Transport watermarking unit 206 includes one or more layer watermarking units including at least one of layer 2/3 watermarking unit 208, a physical watermarking unit 210, and a radio frequency watermarking unit 212. The transmitter 200 receives user data for wireless communication to a receiver. The user data is preferably first protected by the content watermarking unit 202. The user data stream is then processed by higher level processing unit 204 to perform higher level processing. The higher-level processed data is then processed by transport watermarking unit 206. Depending on several system parameters including radio channel quality index, security/protection level, and watermarking message capacity, the adaptive cross-layer watermarking spreader 214 takes the watermarking message as input and distributes and spreads the watermarking message in an adaptive manner to the sub-layer watermarking system in the transport watermarking unit 206.

The individual sub-layer watermarking messages may be the same for all sub-layer watermarking units, unique for all sub-layer watermarking units, or a combination of both. Each sub-level watermarking unit operates independently or in conjunction. The watermark message is embedded in any one or more of the 2/3 th layer, the physical layer, or the RF layer. For example, physical watermarking and radio frequency watermarking may be performed together in a complementary cooperative manner, so that the physical watermarking technique does not interfere with the radio frequency watermarking technique, and vice versa. In addition, each sub-layer watermarking unit may be active or inactive for a certain period of time. The system is adaptive and resilient. The watermarking controller is preferably at a higher layer, and it is preferable to provide the transport watermarking unit 206 with information about where and how the watermarking message should be embedded.

In the RF watermark, the token/key may be embedded in the RF carrier phase/frequency, the transmitted signal waveform, (or filter shaping coefficients), the MIMO coefficients, (or smart antenna configuration), etc. Typically, radio frequency watermarking is radio air interface specific. Examples of radio frequency watermarking include, but are not limited to:

1.) adjusting (or adjusting) the carrier frequency within allowable limits, wherein the total amount of adjustment is an indicator of the watermark bits;

2.) guard time intervals whose individual interval totals correspond to the bit order of the watermark;

3.) importing lower level audio in a frequency spectrum for each audio associated with the watermark message;

4.) changing the spectrum within a licensed spectral mask (e.g., by changing the pulse shaping filter coefficients), wherein a set of filter coefficients is associated with the watermark message; and

5.) use analog random selection of subcarriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, wherein the selection is made based on the watermark being used.

In physical watermarking, tokens/keys can be embedded directly into the bit (or symbol) level of user data. Examples of physical watermarking include, but are not limited to:

1.) use a dirty paper encoding technique as watermark encoding, as will be discussed in more detail later;

2.) the token/key is embedded in the physical channel, so that some of the channel code's redundant bits (forward error correction) are replaced by bits related to the token/key;

3.) initializing a forward error correction shift register with the token/key to transmit the token/key prior to channel coding of the user data stream;

4.) changing physical layer transport format configuration (e.g., by changing modulation and/or coding rate), wherein one set of configurations corresponds to a watermark; and

5.) modulating the amplitude with a constant envelope modulation scheme (second modulation), wherein the total amount of amplitude is indicative of the watermark bit.

The physical watermarking may be independent of or specific to a radio air interface. For example, the first 4 cases of the above-described physical watermarking technique are radio interface independent, while the last case is considered radio interface specific.

In the 2/3 level floating mark, the token/key may preferably be placed in the Least Significant Bits (LSBs) of the control region (e.g., header) of uncompressed user data or compressed user data. In addition, one of the tasks at layer 2/3 is to determine the ratio of transmitting user data and token/key.

The use of watermarking at lower layers of the communication stack, such as the radio frequency and physical layers, can provide advantages. Authentication of wireless communications may occur at lower layers and unwanted communications can be identified at lower layers. As a result, these communications can be discarded or blocked by higher layers by sweeping unnecessary higher layer processes and avoiding the means of being consumed. In addition, because these unwanted communications may not be passed to higher layers, certain attacks on the wireless system, such as denial of service (DoS) attacks, may be prevented, meaning an increase in security of the wireless communication.

Lower layer authentication tends to authenticate a particular wireless connection. As a result, unauthorized individuals who do not use the appropriate link can be identified, which is more difficult and sometimes impossible to achieve at higher layers. For example, an unauthorized user may attempt to penetrate a network by attacking a secure (watermark-level) wireless network, such as active eavesdropping, interception attacks, traffic hijacking, replay, etc. If an unauthorized user does not know a required wireless watermark (token/key) or does not have hardware/software to generate such a watermark, the unauthorized user will not be able to obtain permission to access the secure wireless network despite the user's proper identification of access to the network.

In addition, a physical layer watermarking function can be added to an existing wireless modem and introduced into a system without changing air interface specifications. The watermarking functionality may coexist with an existing air interface and may be selectively turned on or off to selectively introduce secure links, and may be retrospectively introduced into an existing system while maintaining compatibility to the previous.

It should be noted that it is not necessary to use all watermarking techniques in all individual layers, and in a preferred embodiment, any number of watermarking techniques can be used in one or more layers as desired. The cross-layer watermarking scheme can be optimized depending on a known/required level of security and computational complexity.

Fig. 3 is a block diagram of an apparatus 300 for securing wireless communications using cross-layer watermarking in accordance with the present invention. The watermarking architecture shown in fig. 3 is configured in a wireless environment to securely and robustly exchange tokens/keys between a sender and an intended recipient in a transport-level manner using watermarking techniques. The apparatus 300 includes a secure processing unit 310; a data processing unit 320, a cross-layer watermarking unit 330, and optionally a smart antenna processor 340 and a smart antenna (not shown).

The security processing unit 310 controls all watermark embedding processes by sending a node security specification 322 to the cross-layer watermarking unit 330 and the smart antenna processor 340. The security specification typically indicates a hierarchy of security requirements. Depending on the user data and/or security specifications, the security processing unit 310 determines the mechanism and extent of watermarking. The security processing unit 310 includes a token/key generating unit 311 capable of generating a token/key of a watermark. The token/key may be generated based on the user, data stream, link, or packet or on any relevant basis. Thus, a different token/key may be embedded in any user, link or packet.

The data processing unit 320 generates a user data stream. The data stream may be audio, moving image, text, data, or a combination thereof. The generated user data stream enters the cross-layer watermarking unit 330. Additionally, radio channel state information may be provided to the smart antenna processor 340. By way of example, the radio channel state information may be used by the smart antenna processor 340 as adaptive scaling and/or adaptive antenna processing.

The cross-layer watermarking unit 330 receives the token/key from the security processing unit 310 and the user data from the data processing unit. The cross-layer watermarking unit 330 embeds the token/key into the user data stream according to the node security specification 322 specified by the security processing unit 310. The token/key embedded user data is transmitted via an antenna (not shown). When the present invention is implemented with a smart antenna, the smart antenna processor 340 determines the appropriate parameters for beam steering, pre-equalization, eigen-beam forming, etc.

According to the present invention, the cross-layer watermarking unit 330 preferably includes three layers: layer 0 (a radio frequency watermarking layer) 336, layer 1 (a physical watermarking layer) 334, and layer 2/3 (a higher layer watermarking layer) 322. Alternatively, the cross-layer watermarking unit 330 may include layers that are additionally used to perform different watermarking schemes, such as application layer (e.g., content) watermarking.

At layer 2/3, the token/key may be placed in the Least Significant Bit (LSB) of the (uncompressed) user data or control region of the (uncompressed) user data (e.g., a header). Additionally, the 2/3 layer 332 (e.g., a mac layer) may determine the ratio of user data and token/key to be transmitted.

In layer 0 336 and layer 1 334, tokens/keys are embedded directly in user data or physical and/or radio frequency waveforms. The watermarking can be further classified into two stages: radio Interface (RI) independent watermarking and radio interface specific watermarking. Note that radio frequency (layer 0) watermarking is typically radio interface specific, but physical (layer 1) watermarking includes radio interface independent (bit level) techniques and radio interface specific (symbol/waveform level) techniques.

The use of radio interface independent watermarking or radio interface specific watermarking, or both, is preferably determined according to a node security specification that signals from the security processing unit 310. In radio interface independent watermarking, the watermark encoding and embedding functions are not affected by the particular radio interface in which the watermarking is implemented, and they are typically implemented according to a bit-level arrangement. On the other hand, radio interface specific watermarking takes advantage of the features of an existing radio interface, such as signal constellation (or waveform) and the forward error correction (or CRC) structure used in the radio interface. With this classification, radio frequency watermarking can be thought of as radio interface specific watermarking. It should be noted that the watermarking structure is independent of content type and application, but relies on a wireless radio channel.

Optionally, if a smart antenna is used, the token/key embedded data may be further processed by the smart antenna processor 340. The smart antenna processor 340 controls a smart antenna to carry token/key information by utilizing the characteristics of the smart antenna.

Fig. 4 is a block diagram of an apparatus 400 implementing physical and radio frequency watermarking mechanisms in accordance with the present invention. The apparatus 400 preferably utilizes dirty paper encoding for physical watermarking.

As mentioned above, layer 0 watermarking techniques are typically radio interface specific. Thus, the apparatus 400 comprises a radio interface specific watermarking unit 420 for performing radio interface specific watermarking on layer 0. Also as mentioned above, layer 1 and the watermark may be radio interface specific or radio interface independent. Thus, the radio interface specific watermarking unit 420 is configured to perform radio interface specific watermarking on layer 1. In addition, the apparatus 400 includes a radio interface independent watermarking unit 410 for performing radio interface independent watermarking on layer 1. The radio interface independent watermarking or the radio interface specific watermarking or both are performed depending on the node security specifications sent by the security processing unit.

A low-level Medium Access Control (MAC) entity 430 preferably receives a token/key based on the user or data stream and the user data streams from the security processing unit 402 and the data processing unit 404, respectively, and performs a proportional allocation of the tokens of the user data streams. The low-level mac body 430 is preferably located at the physical layer to change channels quickly, such as in UMTS High Speed Downlink Packet Access (HSDPA). The mac body 430 allocates individual token/key ratios and user data based on security specifications, channel state information, and other factors such as available bandwidth and user data requirements.

The radio interface independent watermarking unit 410 includes a dirty encoding unit 412 and a watermark embedder 414. The present invention preferably utilizes dirty paper coding as the radio interface independent watermark. The dpc unit 412 receives the scaled token/key, the user data stream, the smart antenna type (if any), and the pre-coding parameters and encodes the token/key for each user (or data stream) as a function of the user data stream.

In a preferred embodiment, the dirty-paper encoding technique, as explained above, is applied to the watermarking of each token/key at the bit level. Watermark encoding based on dirty paper encoding is radio interface independent but relies on user data (e.g., information encoding). The encoded token/key is output to the watermark embedder 414. The embedder 414 also receives the user data streams and embeds the respective encoded token/key into their respective user data streams.

Fig. 5 is a detailed block diagram of a radio interface independent watermarking unit 410 according to the present invention. In a watermark embedding process, the watermark embedder 414 examines the user data for preparatory embedding (e.g., informed embedding), in an attempt to achieve a compromise between some conflicting requirements including robustness and perceptual authenticity. As shown in FIG. 5, after adding user data, a simple embedding technique may scale the encoded token/key with a scaler (scaler) 418. The problem of designing a watermark embedder 414 can be considered an optimization problem. The watermarked user data is sent to the antenna for transmission.

Referring again to fig. 4, it should be noted that radio interface specific watermarking may be implemented by a radio interface specific watermarking unit 420 according to node security specifications. Also, the radio interface specific watermarking may be implemented separately or together with the radio interface independent watermarking. The radio interface specific watermarking unit 420 receives the token/key from the security processing unit 402 and performs radio interface specific watermarking on a new user data stream or a user data stream embedded with a radio interface independent watermark.

By way of explanation, the following is a description of a watermarking technique specific to a radio interface as it may be applied to an Orthogonal Frequency Division Multiplexing (OFDM) radio interface and a Code Division Multiple Access (CDMA).

The radio interface specific watermarking technique that can be implemented in an orthogonal frequency division multiplexing system is as follows. It should be noted that these techniques may also be implemented in other types of radio interfaces, and are provided by way of example only, as other techniques may also be used.

Pilot sub-carrier-the use of an orthogonal frequency division multiplexing PLCP Protocol Data Unit (PPDU) is split into a number of sub-carriers before it is transmitted. For example, the IEEE 802.11 standard specifies that an ofdm phy layer separates a PLCP protocol data unit into 52 separate subcarriers, 4 of which are dedicated to pilot subcarriers. Typically, all subcarriers are encoded with similar data, e.g., +1 or-1, to serve as the reference plane for the demodulator. The predetermined code is scrolled between orthogonal frequency division multiplexing symbols. With watermarking according to the invention, a particular pilot subcarrier is manipulated with exactly the opposite information that it expects. For example, a pilot subcarrier that is expected to be coded at +1, may instead be steered to include a-1.

Frequency hopping — this mechanism utilizes an orthogonal frequency division multiplexed carrier frequency to transmit the watermarking information. In current wlan implementations, the receiver must obtain the rf carrier frequency offset of the transmitter for each ofdm packet transmission. According to the invention, the carrier frequency of the transmission is modified by adding or subtracting several hundred or several kilohertz within an acquisition range in a predetermined pattern. The pattern of the central frequency that fluctuates with time provides hidden bit information, such as a watermark. For example, a demodulator that determines to receive a carrier frequency higher than expected may represent a +1, but a demodulator that receives a carrier frequency lower than expected may be used to represent a 0.

The radio interface specific watermarking technique that can be implemented in a cdma type system is described below. It should be noted that these techniques may also be implemented in other types of radio interfaces, and are provided purely by way of example, as other techniques may also be used.

To steal spread spectrum code chips for watermarking-in cdma systems, spread spectrum codes are used to separate mobile devices or base stations. In this example, certain chips in the spreading code are selected and watermark information is embedded in those chips (e.g., left intact if 0 and flipped over if 1). In this example, the selected chip locations are known at both the transmitter and receiver.

Frequency Shift Keying (FSK) modulation based watermarking with spread code variations-for watermarking, slow spread code variations are applied at the carrier frequency of the watermarking information and on top of the variations of the frequency shift keying modulation in such a way as to set a low frequency drift above the carrier frequency (for example by gradually increasing the frequency up or down in small frequency steps). The watermark information is mapped to a predefined frequency offset. When spreading code variation occurs, a local descrambler at the receiver must be synchronized to produce the same spreading code variation (representing the watermark information).

Although radio interface independent watermarking is typically implemented at the transport channel or bit level, radio interface specific watermarking is preferably performed at the bit, symbol, pulse shaping level, or any combination thereof. For example, in a watermarking system specific to a spread spectrum technology type (including code division multiple access), the token/key information may be represented as a spread spectrum code (including channelization codes and scrambling codes).

The token-embedded user data stream provided by the radio interface-specific watermarking unit (or radio interface-independent watermarking unit) may be further processed by a smart antenna processor to increase the degree of watermarking security/robustness. The smart antenna (or mimo antenna) may be implemented as a beamformer, a pre-encoder (or pre-equalizer), or a diversity antenna. For example, a token/key may be represented by using information about the antenna, including characteristics of antenna pattern (beam), antenna weight, delay between antenna elements, antenna spacing, antenna hardware information, antenna state (directional or omnidirectional), antenna configuration, antenna switching rate, antenna control consistency, antenna cross-correlation, and spatial distribution. In addition, a precoding (or eigen-beamforming) approach may be used, particularly in multiple-input multiple-output channels, to provide physical layer resistance to potential forms of eavesdropping attacks. This approach utilizes spread space-time (multiple-input multiple-output) channels along with coefficients of a pre-encoder (or eigenbeamformer). In mimo systems, the mimo channel, as generated by the various antenna elements, can be viewed as a spatial spreading function. In the case of watermarking, the transmitted mimo waveform may be modified to indicate the bits of the watermark. For example, a matrix resulting from SVD (singular value decomposition) in mimo communication, may be used to carry bits so that a particular rotation sequence used in the matrix is used to carry the watermark. When a smart antenna system is implemented with beam steering or (eigen) beam forming mechanisms, mac may also allocate users between (eigen) beams.

When the communication device communicates with other communication devices (e.g., broadcast channels), the token-embedded user data stream of the respective receiving device can be further processed by the dirty-coding unit (see fig. 5) for multicasting 416 in order to take advantage of the dirty-paper coding of multicast/broadcast, so that the dirty-paper coding can achieve the total proportional capacity of the mimo broadcast channel. The dirty-paper encoding of the token encoding and the dirty-paper encoding of the broadcast may be performed together. The dirty paper encoding function of the broadcast is not available for point-to-point communication.

It should be noted that the present invention can be applied to both downlink (broadcast) and uplink (multiple access). In the downlink, broadcast transmission may be maximized according to the total transmission rate. In addition, the dirty-paper encoding function of the broadcast may be further optimized in view of the smart antenna technology implemented. Cross-layer watermarking (including radio interface independent/unique watermarking) can maximize watermarking performance. As a technique, dirty-paper coding has applicability for efficient broadcasting and efficient watermarking of data, making it a tool that can handle these needs in a single implementation, either jointly or separately.

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.

Claims (48)

1. A method of enhancing security of communications transmitted by a communication device, the method comprising:

providing a cross-layer watermarking unit in the communication device, wherein the cross-layer watermarking unit comprises at least one of a 2/3 th layer, a 1 st layer and a 0 th layer;

generating a watermark token/key;

selectively transmitting user data while embedding the token/key into the user data for transmission in one or more layers according to a security specification; and

authenticating the user data with the token/key embedded in the user data transmission.

2. The method of claim 1 wherein the token/key is Radio Interface (RI) dependent or radio interface independent for selectively embedding the RI dependent token/key, the RI independent token/key, or both.

3. The method of claim 1 wherein embedding the token/key is accomplished using Dirty Paper Coding (DPC).

4. The method of claim 3 wherein said dirty-paper coding is further used for broadcasting and multicasting said user data.

5. The method of claim 1 wherein embedding the token/key is performed using a signature of the communication device.

6. The method of claim 5 wherein the signature is a hardware nonlinearity of the communication device.

7. The method of claim 1 further comprising a step of processing parameters received at a processor of a smart antenna for embedding the token/key in the user data transmission.

8. The method of claim 7 wherein the token/key represents information about the smart antenna.

9. The method of claim 8, wherein the information includes at least one of characteristics of antenna pattern, antenna weight, delay between antenna elements, antenna spacing, antenna hardware information, antenna state, antenna configuration, antenna switching rate, consistency of antenna control, antenna cross-correlation, and spatial distribution.

10. The method of claim 7 wherein the users are allocated between beams.

11. The method of claim 1 wherein the token/key is generated based on a concatenation.

12. The method of claim 1 wherein the token/key is generated based on a data packet.

13. The method of claim 1 wherein the token/key is located in a least significant bit of the user data.

14. The method of claim 1 wherein the token/key is located in a control area of the user data.

15. The method of claim 1, further comprising the step of performing watermarking in a layer higher than layer 2/3.

16. The method of claim 1 wherein the token/key is one of a signature specific to a generator, a signature specific to a radio modem, and a low data rate stream.

17. The method of claim 1, wherein the watermarking is performed using at least one of: modulating carrier frequencies within permitted limits, changing guard time intervals whose respective spacing amounts correspond to a bit order of the watermark, introducing lower-level audio in a spectrum in which each audio is associated with a watermark message, changing the spectrum within a permitted spectral mask, wherein a set of filter coefficients is associated with a watermark message, and using analog randomly selected subcarriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, wherein the selection is made according to the watermark used.

18. The method of claim 1, wherein the watermarking is performed using at least one of: a Dirty Paper Coding (DPC) technique for watermarking coding, embedding the token/key in a physical channel such that some of the redundant bits of the channel code are replaced with bits associated with the token/key, initializing a Forward Error Correction (FEC) shift register with the token/key to transmit the token/key, changing the physical layer transport format configuration prior to channel coding the user data stream, wherein a set of configurations corresponds to a watermark, modulating the amplitude with a fixed envelope modulation scheme, wherein the total amount of the amplitude is indicative of the watermark bits.

19. The method of claim 1 wherein the communication is transmitted in an Orthogonal Frequency Division Multiplexing (OFDM) system.

20. The method of claim 19 wherein the watermarking is performed by steering pilot subcarriers.

21. The method of claim 19 wherein the watermarking is performed by modifying the transmitted carrier frequency with a predetermined pattern.

22. The method of claim 1 wherein the communication is transmitted in a code division multiple access system.

23. The method of claim 22 wherein the watermarking is performed by stealing spreading code chips in a predetermined pattern.

24. The method of claim 22 wherein the watermarking is performed by applying a low frequency drift above a carrier frequency with spread spectrum code variations on the carrier frequency and Frequency Shift Keying (FSK) modulation of the watermarking information on top of the variations.

25. An apparatus for increasing security of a communication, the apparatus comprising:

a security processing unit configured to generate a token/key for watermarking and transmitting a node security specification;

a data processing unit configured to generate user data; and

a cross-layer watermarking unit comprising at least one of layer 2/3, layer 1 and layer 0, wherein the cross-layer watermarking unit selectively embeds the token/key in user data transmissions on at least one of these layers according to a security specification.

26. The apparatus of claim 25 wherein the token/key is Radio Interface (RI) dependent or radio interface independent, whereby the cross-layer watermarking unit selectively embeds a radio dependent token/key, a radio interface independent token/key, or both.

27. The apparatus of claim 25 wherein the token/key embedding is accomplished using Dirty Paper Coding (DPC).

28. The apparatus of claim 27, wherein the dirty-paper coding is further used for broadcasting and multicasting user data.

29. The apparatus of claim 25 wherein the embedding of the token/key is performed using a signature of the communication device.

30. The apparatus of claim 29 wherein the signature is a hardware non-linearity of the communication device.

31. The apparatus of claim 25 further comprising a smart antenna processor for embedding tokens/keys into the user data transmission.

32. The apparatus of claim 31 wherein the token/key represents information about a smart antenna.

33. The apparatus of claim 32 wherein the information comprises at least one of antenna pattern, antenna weight, delay between antenna elements, antenna spacing, antenna hardware information, antenna state, antenna configuration, antenna switching rate, antenna control consistency, antenna cross-correlation, and spatial distribution.

34. The apparatus of claim 31 wherein the users are allocated between beams.

35. The apparatus of claim 25 wherein the token/key is generated for each connection.

36. The apparatus of claim 25 wherein the token/key is generated for each data packet.

37. The apparatus of claim 25 wherein said token/key is located in a least significant bit of said user data.

38. The apparatus of claim 25 wherein the token/key is located in a control area of user data.

39. The apparatus of claim 25 wherein the cross-layer watermarking unit further comprises a layer higher than layer 2/3 for performing higher layer watermarking.

40. The apparatus of claim 25 wherein the token/key is one of a generator specific signature, a radio modem specific signature and a low data rate stream.

41. The apparatus of claim 25 wherein the watermarking is performed using at least one of: modulating a carrier frequency within allowable limits, changing a guard time interval whose respective interval amounts correspond to a bit order of the watermark, introducing lower-level audio in a spectrum in which each audio is associated with a watermark message, changing the spectrum within an allowable spectrum mask, wherein a set of filter coefficients is associated with a watermark message, and using analog random selection of sub-carriers in an Orthogonal Frequency Division Multiplexing (OFDM) system, wherein the selection is based on the watermark used.

42. The apparatus of claim 25 wherein the watermarking is performed using at least one of: a Dirty Paper Coding (DPC) technique for watermarking encoding, embedding the token/key in a physical channel such that part of the redundant bits of the channel code is replaced with bits associated with the token/key, initializing a Forward Error Correction (FEC) shift register with the token/key to transmit the token/key prior to channel encoding of the user data stream, changing the physical layer transport format configuration, wherein a set of configurations corresponds to a watermark, modulating the amplitude with a fixed envelope modulation scheme, wherein the total amount of the amplitude is an indicator of the watermark bits.

43. The apparatus of claim 25 wherein the communication is transmitted in an Orthogonal Frequency Division Multiplexing (OFDM) system.

44. The apparatus of claim 43 wherein the watermarking is performed by manipulating pilot subcarriers.

45. The apparatus of claim 43 wherein the watermarking is performed with a predetermined pattern modification of the transmitted carrier frequency.

46. The apparatus of claim 25 wherein the communication is transmitted in a code division multiple access system.

47. The apparatus of claim 46 wherein the watermarking is performed by stealing spreading code chips in a predetermined pattern.

48. The apparatus of claim 46 wherein the watermarking is performed by applying a low frequency drift above a carrier frequency with spread spectrum code variations on the carrier frequency and Frequency Shift Keying (FSK) modulation of the watermarking information on top of the variations.